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Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]28

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Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

(OP)
This is the continuation from:

thread815-445840: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 1]
thread815-450258: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 2]
thread815-452000: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 3]

This topic is broken into multiple threads due to the long length to be scrolled, and many images to load, creating long load times for some users and devices. If you are NEW to this discussion, please read the above threads prior to posting, to avoid rehashing old discussions.

Thank you everyone for your interest! I have learned a lot from the discussion, too.

My personal point of view, since this falls close to (but not exactly within) my discipline, is the same as that expressed by many other aviation authorities: that there were flaws in an on-board system that should have been caught. We can describe the process that "should have happened" in great detail, but the reason the flaws were allowed to persist is unknown. They are probably too complex to reveal by pure reasoning from our position outside of the agencies involved. Rather, an investigation of the process that led to the error inside these agencies will bring new facts to light, and that process is under way, which will make its results public in due time. It may even reveal flaws in the design process that "should have" produced a reliable system. Every failure is an opportunity to learn - which is the mandate of the agencies that examine these accidents.

Some key references:

Ethiopian CAA preliminary report

Indonesian National Transportation Safety Committee preliminary report

The Boeing 737 Technical Site

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I have had a look at Angle of slip sensors.

It appears that to get a real reading using a sensor you need a huge probe out the front into clean air. Certain test flight aircraft have them.

But it seems they use the output from the INS or AHARS, heading and track from GPS and air data computer gives the other stuff, and then derive a angle from that. The slip ball indicator is AHARS derived.

But to be honest its way over the tech knowledge required by pilots of the type on how these things are calculated. Looking at the list of variables outputted by the data recorder it is calculated for my type but how it does it I have no clue.

I suspect that test aircraft are used to calibrate the internal derived data for slip angle and then that's what's used.

To note for commercial aircraft the only time the aircraft is in slip or skid like that is when you are operating single engine and you haven't sorted your rudder trimming out yet and when your doing a cross wind landing. The rest of the time its ball in the centre for coordinated flight. Apart from anything else if you fly with the aircraft skidding all the time you will get ear ache off the cabin crew and increase the likely hood of the pax barfing down the back. And it will increase your fuel burn. I might add the ear ache off the cabin crew is enough that you don't do it unless you want to go hungry and not have a cup of tea while the sun comes up.

To note I have been shown the price list for the MAX and the customer options. To be honest I am a bit scared and won't post it because of all the legal exposure that gives. But the option to give the pilots a AoA indicator on the PFD and additional AoA mismatch warning was utterly disgustingly expensive for a safety addition, for what is only an activation of some code to display a value which is already available and being used for no additional hardware. No accountant would pay that price for something that's not required.

Hell as a Scotsman and pilot I wouldn't pay it either. But then again it was two Scotsmen fighting over a penny that invented copper wire so maybe I am not the best person to do that cost analysis.

Anyway they will all have it now, but I suspect even having it wouldn't have changed the outcome of the two aircraft unfortunately.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Just a link from this side of the pond. I can't see that being complete before the end of this calendar year. And I also can't see the other CAA's doing anything until after the EASA review is complete mainly due to cultral face issues if it turns out that it turns up issues which I suspect it will with the elevator power V stab power. If the tail and controls needs redesign and certification we could be talking a year at least.

https://www.bloomberg.com/news/articles/2019-05-28....

And one from Boeing from just before it was rejected by the FAA. They haven't given the reason yet for the rejection.

https://www.boeing.com/commercial/737max/737-max-s...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

(OP)

Quote (Alistair Heaton)

I have had a look at Angle of slip sensors.

I found an angle of slip indicator for you. Works great in aircraft where the windscreen IS THE Primary flight display.
Think it would work on a 737?

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I am interested in any pilots comments on this statement:

Quote (Boeing Statement)

There are no pilot actions or procedures during flight which require knowledge of angle of attack.
Link

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Everything is referred to speeds for weight which are given for the envelope range.

This then puts you in the correct AoA.

Military pilots of fast jets fly the AoA for carrier landings which means they don't have to worry about the aircraft weight.

For landing you land at 1.21 of stall speed in commercial aircraft. This is a fixed angle of attack.

Civilian world they for some reason which I can't understand do not want the pilots using AoA.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

(OP)
Airspeed is normally a very good proxy for AoA. It is measured fairly directly, in conjunction with other aerodynamic parameters, so you can have a good idea of how fast you are going, not just horizontally but vertically and how high you are, all from two simple tubes.

The errors that build up as you increase altitude grow exactly in proportion to the effect altitude has on your angle of attack, therefore, your indicated airspeed still tells you what you need to know.

Because angle of attack can be changed in seconds with the stick, any device to deliver to the pilot AoA info would have to do it continuously, without lag or overshoots. What would a pilot do with the AoA information on a second-by-second basis that can't be done by airspeed?

Bad things happen when pilots fail to second-guess a faulty airspeed indicator. Would the same happen if they had an AoA indicator, which then went bad?

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Thanks for the explanation, Alistair and SparWeb.

Another question.
I understand that there are several inputs that already caused automatic trim adjustment.
Is speed trim the correct term?
Is AoA information just an added input to the speed trim system with a new name, or is MCAS an additional stand alone system?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

AoA is one of these things which is progressively getting used more and more. It started just being involved with the stall system but now gets used by various other systems. Eg the FMC to get most economic flight profile settings.

You are correct that you trim for a speed but people don't call it that.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I don't have a clue how it's all intergrated. The base control system is easy enough but when you start looking at what boxes are talking to each other and it gets complicated.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

There is a Speed Trim System on 737s that automatically changes the trim to match the speed. AoA is also used as a correction for the Pitot-Static system to provide accurate airspeed.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"Speed Trim System (STS)
An electrical stabilizer trim input automatically controls certain aircraft attitude conditions when undergoing large thrust changes in the lower speed region, such as takeoff and go-around. These conditions require high thrust settings and are especially present with a low weight aircraft and a relatively aft center of gravity where the aircraft wants to “nose up”. The STS supports the crew during these conditions when manually controlling the aircraft without the use of an autopilot by an opposite stabilizer trim, commanding a nose down force by use of the autopilot trim.
STS activates:
– Between 100 KIAS and Mach 0.60 (fading to zero after M 0.68)
– 10 secs after takeoff
– 5 secs after releasing trim switch(es)
– N1 >60%
– Autopilot disengaged
– Trim required
A short manual trim selection overrides the speed trim and will inhibit it for around 10 seconds, just in case that the speed trim inadvertently provides an incorrect input.
The SPEED TRIM FAIL light Illuminates amber:
– accompanied by the FLT CONT annunciator and MASTER CAUTION with a failure of the STS
– after RECALL is pushed together with the FLT CONT annunciator and MASTER CAUTION but extinguishes when Master Caution System is reset with a single FCC channel failure.
The stabilizer speed trim itself (not to be confused with STS) depends on flap position as it is most needed with the flaps extended around the takeoff and landing phase.
When the flaps are up, the low speed trim moves the stabilizer at 0.2 ups (units per second) and when the flaps are extended the high speed trim moves the stabilizer at 0.4 ups.
This stabilizer speed trim is available during autopilot operation, than stabilizer trim speed changes when the flaps are up to 0.09 ups and when the flaps extended to high speed of 0.27 ups."

Seems there is another system for dealing with flight characteristics.

Is that the system you mean or is there another one?

The list of what AoA is used for these days is huge and it sneaks in as 3DDave says to do corrections on multiple systems. It its also involved in the rudder systems eg yaw damper.

Quite how the 737 deals its inputs and failure modes I really don't know. With electrical failures its normal for systems to progressively be shed and as the heaters are reasonably high load one side of the Pitot static system is shed, I can only presume one of the AoA vanes also goes but don't know. It could be both of them. But if this then automatically then kills the AoA usage I don't know. If the electric trim has already been shed as well then it won't matter.

On my type we loose what we call the low speed cue which is the stall protection which does give you an idea of AoA but not a real value quite soon in the proceedings. Now if this is due to a safety assesment that its more likely to cause issues than solve them or the sensor is off line I have no clue. The only bit of advice in the QRH when you get it is "maintain a safe airspeed for the conditions" and its a de brief point if you don't work you way through to that checklist for that obvious advice in the sim.

And another punch in the guts for 737 operators if they haven't got enough to deal with just now trying to plug holes timetable.

https://www.cnbc.com/2019/06/02/boeing-notifies-fa...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Sparwweb,

My own personal opinion ( based only on the publically reported summaries) is that the reason for the failure to catch the basic design error is neither complex nor complicated, but instead it is too simple to accept publically. The instant problem was just the nexus of 2 common faults in our system of government regulation and corporate management.

In nearly all large companies the weight given to sales success decisions simply outweighs all other considerations, as measured by the corporate internal poltical power given to sales VPs and their commercial decisions ( together with incentives such as bonuses etc) are totally focused on sales success. Likewise, the evolution of our government regulation mechanism has, in all instances without exception, caused the regulators to be "owned" by the regulated industry.This instant spate of fatal accidents will not change either of these systemic defects , and the current effort is merely focused on finding words and narratives to help cover these systemic issues that are integral to our way of life.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I agree. These incidents are looking less like engineering failures and more like corporate management failures.

I'm sure engineers raised red flags along the way but what are they in the path of an ill conceived corporate agreement to make red lines with green ink.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Based on personal interaction with several Boeing Systems Engineers, I know where I would start digging.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Is there likely to be a commission type thing aka what they had after the shuttle failure of the solid booster o rings in the cold?

Just been reading the book by the engineer that spoke out about the whole thing then took the lead on the redesign.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

(OP)
No.
Boeing is not a public agency like NASA.
Several state legislatures would burn down before that kind of inquiry happened.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I wasn't thinking Boeing would be the focus of the commission. They were only playing the system.

The system would be the focus of the commission.

They need to do something. If the US system is deemed none compliant by the rest of of the worlds CAA's then it becomes a very difficult market for any aviation product from the USA.

Sparweb just seen the perfect angle of slip indicator :D The first form of HUD ever and works a treat. Failure mode the bit of string comes off.... Effect on flight zero.... Fix another bit of string.....

Unfortunately the boundary layer on the windscreen on powered twin aircraft means it won't work. A few times I have had feathers trapped in the wipers to see the effect.

Oh that's another completely useless system on all commercial aircraft.... the wipers. Highly expensive to maintain, create loads of noise in the cockpit, utterly useless for doing the job they were fitted for. Thankfully centre line lighting does work, as does taxing by brail.

Takes me back to the day.... I came to gliding after doing power. Gliding makes you aware of the rudder pedals even more than flying tail draggers. Can't wait until my kid is old enough to be able to go gliding...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

if extrapolating from previous experience (gulf oil spill):
For some company managements there's seemingly but one way to bring them back into conciousness, that's litigation with relevant sums at stake.

Then, did the Boeing system engineers know about the faulty design? i use this word, to be technically clear. That's not an accusation. Did someone there rise the red flag?

This would be the person to start rebuilding the system & also public confidence, similar to Alan McDonald & the boosters for the Shuttle.

Why not respecting, demanding, encouraging diverging technical opinion as proof of soundness within the design world?

Roland Heilmann

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

There seems to have been many red flags.

One of the test pilots has stated that when he tested the system early on there was two seperate sensor systems linked to the MCAS. They had both AoA's in the loop and the aircraft G and it was limited to one input cycle of the reduced amount and you needed to be in the high positive G section of the flight envelope. He still wasn't happy with it and said so. But as the system needed high G as well as AoA input he relalistically couldn't see it activating so with reservations said it was OK.

He has since left Boeing and now flys for a US airline and was as surpised as everyone else when the production system as fitted to the MAX became public knowledge it was very far away from what he had signed off.

https://www.planeandpilotmag.com/going-direct-boei...

https://www.nytimes.com/2019/06/01/business/boeing...

And this article has loads in it how the various flight augmentation systems work on the 737

https://www.satcom.guru/2018/11/737-fcc-pitch-axis...

"This would be the person to start rebuilding the system & also public confidence, similar to Alan McDonald & the boosters for the Shuttle."

Sully could be a face for the team...... But as there are more than likely voodoo dolls of him around the US getting daily stabbings I doudt he would be acceptable to the main industry players. But he would sort the public confidence side of things if he said it was now good.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

In the old days of digital computers, the golden rule was GI=GO, or garbage in = garbage out. To base a critical computer response algorithym on an assumption that a single instrument was fabricated correctly, calibrated correctly ,maintained correctly and not damaged from airfield debris seems to be a gross error.I had thought that components of commercial airliners were designed using probability based on a 3*std deviation proof , but I guess that rule is no longer used anymore

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

IRstuff - control systems or Systems? Was your primary product Powerpoint slide decks and your goal to present at an INCOSE symposium?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Weapon target and acquisition systems, and I've never been to an INCOSE symposium nor produced any Powerpoint slides for any.

I think it's more than a bit insulting to assume that all systems engineers are paper-pushers; it may be the case that many are, just as there as many designers who don't bother understanding their requirements. The systems engineering process is the minimum threshold required to manage a design, but as with a PE license, it does not guarantee a successful design; that still requires knowledgeable systems and design engineers to produce a valid product. You can look to Uber's and Tesla's fatalities to see identical processes at work with identical lack of understanding of requirements.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I can look at FCS as well.

I'm looking at the Systems Engineering slides where SEs are the central and controlling figures for the entire development process, considered the sole source of knowledge and their general lack of experience in managing and understanding failure is clearly shown by the manner in which INCOSE supplies the concept that if one just keeps track of requirements and does a pile of AoA paperwork that that is enough.

The way that the process failed in the 737 Max matches my experience with high-level SEs.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

OK, fair enough; I worked on FCS, and it was snafu'ed by by a bunch of problems, but the big issue isn't the systems engineering, per se, it's the lack of knowledgeable SMEs trying to go through the process. As I alluded to earlier, even a perfect process still requires experienced engineers; you can't parse or question requirements that you don't fundamentally understand. Part of the systems engineering process includes a System Requirements Review (SRR) wherein you hash out the interpretations and scope of each requirement; that can't be done with people that have no experience.

This is no different than Uber hiring a bunch of LIDAR and image processing guys that only understand target segmentation, and not target tracking. The end result is that Uber's target processor detected the pedestrian, but ignored the fact that the pedestrian was on an intercept course well before the pedestrian actually got into the path of the car. So, whatever faults Boeing has, it's nowhere unique, since both Uber and Tesla have almost identical issues with processing of targets beyond the basic detection step.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Quote (IRstuff)

but the big issue isn't the systems engineering, per se, it's the lack of knowledgeable SMEs trying to go through the process. As I alluded to earlier, even a perfect process still requires experienced engineers;
As far as engineers on this project.
I am sure that Boeing managers carefully selected the engineers for the Max project.
It is easy to imagine that any engineer with the moral courage to stand up to management and say:
"This is wrong."
would not be on the team.
One engineer with such moral courage slipped through the net.
When he did stand up to management, and was supported by his team and another senior engineer, he was quickly removed from the program.
I am sure that the engineers did their best.
The best engineers may not have been chosen for the Max team.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

You don't have to try hard to create systems where self-reporting is a precious thing to do. Just basing bonuses and raises on the number of self-reports will passively prevent 95%+ of a team from bringing up an issue. Why should anyone fight too hard if they will likely be on another project,contract, or company in a few years anyways? OSHA in their safety guidelines strongly discourages financial rewards be tired to self-reports. I am sure those engineers at Boeing had a manager breathing down their neck over deadlines. Any pushback would probably be a career mistake. At Wells Fargo, you just had to create unrealistic expectations and make people afraid to get them to be unethical. Companies with poor ethical culture in my opinion more times than not are that way by design.

------------------------------------------------------------------------------------------
If you can't explain it to a six year old, you don't understand it yourself.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

In the pilot side of things self reporting is a variable topic. I am lucky in my current job that a flight safety report goes to the flight safety department who are separate to the fleet management. And I am pretty happy the way it works and issues dealt with.

For the vast majority of things it usually heads out to either the Engineering side of things or operations. A quick interview to see what the crew did and you get the results a bit later.

If its due to a crew screw up they dig in and find out the root cause. Then deal with it. Thats not to say you can't be fired over something you have submitted if you have been negligent or there is shall we say history. But to my knowledge nobody has been fired for a one off event. Even to the point of structural damage to an aircraft.

Heavy landings are always an issue with any airline especially as FO' come on line and float up the experence curve. Thats not to say Captains don't do them as well. The hardest I have done in the dash was 1.89G the trigger for heavy landing is 2.1G. It was my own fault didn't put enough power in when we got sink in the flare and hit the pitch limit and arrived. Calm winds and 10k viz so no excuse. Apologised to everyone on board and that was that. Must admit when the FO does one I take the blame, well ultimately everything is the fault of the Captain even if its not them flying the aircraft.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

https://www.reuters.com/article/us-france-airshow-...

"...Boeing’s Test & Evaluation group is developing the technology to replace costly and labor intensive physical safety tests used for decades - such as using machines to bend the wings to extreme angles and shaking the fuselage until it cracks - with computer modeling..."

I see no way in which this could possibly go wrong.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

BBC - Battle over blame

Includes some interesting details, clearly explained.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

BBC are doing quiet well over reporting the whole thing.

There is huge cultral differences surfacing around the world over the removing thrust issue. I must admit the European thoughts are that it is understandble why they didn't remove the power with the pitch power couple adding to the nose down.

The only other thing I have seen and heard is that the whole use of the trim system is under review on the NG including its use for the STS system.

There is a fundememntal reduncancy issue using the trim stab for anything with its ability to produce outside pilot controllable or recoverable control forces.

Putting through adjustments shall we say through the elevator isn't a problem because if anything goes wrong the trim stab at 32m sqrt V 7m sgrt will easily over power the elevator in both extremes and you have the option of just killing the hydralic power to the elevator. It can also be protected from causing structural damge at high speed using blow back pressure release valves.

The STS on the 800 is okish but is getting huge frowns and why the hell was that let through, but as its linked to the pitot system which has multiple sensors and an extremely mature set of procedures and sensor error catching logic I can't see an issue with it. PLus it hasn't had any issues so far. So I don't think they are going to enforce changes to the 800.

The crux seems to be the window that the pilot has to catch the aircraft before it gets into an unable to manually trim the aircraft hole. Its apparently suprisingly small on the 800 and max due to the gearing of the manual trim system.

And I susepect there will be a new certification rule on the subject and no grandfather bypasses for future new versions for all OEM's.

There has been chat of adding a powered manual trim system but that brings new failure modes as well.

My thoughts are that a hydralic motor driven off the elevator hydralic supply via a PT couple with a backup electrical pump and/or accumulator might be an option. When the electric trim is turned off the hydralic system is powered up and you will have 3000 psi to assist moving the stab. But we shall see.

So realistically the MCAS system and its software fix is pretty much is the least of Boeings problems. They have to solve the whole of the Elevator/trim system design and logic plus failure modes etc etc. I also can't see now the FAA releasing the aircraft for US airspace in September with only a software fix. They will not break ranks now with the other authorities.

They are also having issues with the folding wing tips on the 777 new variant. The failure modes of them and the indications and the control power of a one side has flipped up is getting very closely looked at. PLus a load of stuff that would have got waved through by the FAA pre MAX is getting the full monty oversight.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

STS = Speed Trim System?

But what you're saying is that there is now a push to go right back to basics on use of stabilizer trim vs elevator control??

Wow.

I do get the issue over the pilots both not re-trimming all the way back to where they were before they pulled the cut-outs, but the criticism the poor guys are getting about speed control of an aircraft which was barely climbing and doing something counter intuitive (reduce thrust) would be very difficult to assess in such a stressful condition is, IMHO, excessive.

The fact the Ethiopian crew couldn't physically turn the smaller (than the legacy 737s) manual trim wheel which the Boeing guidelines claim they could is the key issue here and clearly got the regulators worried. They clearly can't re-design the relative sizes of the elevator versus stabilizer so it must be something that they are looking at.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

It's a can of worms this has opened up.

Quiet where they will wiggle off to I have no clue.

There is lumps of organic fertilizer which were thought to be wrapped up nicely and hidden starting to leak and people are following the smell and finding them.

And while looking for the leaking ones they are finding other ones that haven't leaked yet but explode when you touch them.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

There has been criticism of the pilots training and actions.
According to the BBC, (linked by VE1BLL)

Quote (BBC)

This checklist - which is meant to be memorised by flight crew - instructed them to flip switches on the centre console, to turn off the stabiliser electronics, then balance the aircraft using manual trim wheels beside the pilots’ knees.
The pilots were in an emergency situation and followed the memorized procedures.
Congressman Graves has criticized the pilots for not reducing power.
They had conflicting information and followed the Boeing procedure and it didn't work.
Why didn't the pilots not reduce power?
Why is reducing power not on the memory checklist?
Congressman Graves may have more credibility if he asked this question instead.

Ethiopian Airlines rejects any suggestion that its training standards fall short. Tewolde says the company has invested more than $500,000,000 (£396,000,000) on its Aviation Academy over the past five years Within the academy, rows of flight simulators sit in two vast hangars. Large, unwieldy-looking boxes on stilts, they sway and swerve as they replicate the movements of giant airliners. These simulators cost millions of dollars each. The company has one for each of the large airliners in its fleet, including the Boeing 787 Dreamliner, the Airbus A350 – and the 737 Max. The latter is something of a rarity. There are still relatively few in service, and this is the only one in Africa. It started operating in January Well, suppose that the pilots had been trained on the State of the Art 737 Max Simulator? They probably would still have died. Another gotcha from Boeing, Quote (BBC) Yet one thing the simulator cannot yet do is replicate the circumstances of that accident or the previous crash off Indonesia. In late May, Boeing admitted that software provided to simulator operators was flawed, and incapable of reproducing some flight conditions, including the failures experienced by ET302 I understand that older versions of 737 simulators can do a more accurate job of replicating the forces that the pilots experiencedin the 737 max than the 737 Max simulator. There has been criticism of Boeing bashing. There are also some Boeing apologists and Boeing boosters who are very active. Did you know that Boeing has 14,566 employees in Missouri? Second only to Washington state and ahead of California. That's a lot of Votes for Congressman Graves. I think that potential votes may color his comments on the pilot's actions and training. Engineering by management decree doesn't always work well. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] The BBC coverage is sensationalist, which makes sense for them. It's also largely inaccurate with just enough truth in there to support the flaws. They imply that MCAS inputs are unstoppable large step inputs and that the pilots need to physically overpower the system rather than move a thumb. MCAS is a problem and it will be fixed, but the 737 Max is not the only plane driven into the ground by badly handled stab trim problems; it is the first to demonstrate the glaring gap in pilot training, but investigating that gap would demonstrate that pilots are a part of the steps to disaster. ET302 didn't follow the AD. They did some things on the list, just not completely, and finally, they did the one thing the AD said should not be done. The simulator does not do a good job simulating operations outside the safe operating envelope. Shocking. I'd give the BBC and other articles some small level of credence if they included the first MCAS-problem flight, the one that landed safely, and then asked, if it was so similar to the others, what was the difference? I'm betting on training and actual trim experience. Oh - since no one called that first crew "Heroes," why claim that only "hero" pilots could save them? RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I agree with that 3D But it's always a problem with public media and aviation. The hero pilot bit gets to the pilots never mind the rest of the team. "Hero pilot avoids hospital" we don't have a clue where hospitals and schools are. They are not depicted on any charts unless it's your local airport you will only know it's a big building and best avoided if your going to crash. The pilot training is an issue. But regulators have even taken a step back from that. In my day your initial instrument rating test was done by a caa staff examiner. These days it's done by a self employed examiner who if they fail to many they just don't get used. Same in the SIM it wasn't uncommon for a quality caa examiner to turn up at the SIM center and spend the day auditing every session. Haven't seen that for years. Training the pilots.... An hour in the SIM costs 1400 euro ish an hour just for hardware rental for two pilots. 3 crews per aircraft a SIM session is 4 hours. And three sessions would not be unreasonable for difference training So per aircraft call it 50 000 euros. There are 4500 of them on order. So 225 000 000 euro. Just for SIM hire Not counting hotac, 4 days lost line flying, the cost of the instructor etc etc. To be honest it would be cheaper to train the engineers to make aircraft that are within the current skill base. And I have said before you need to design and expect for the reactions of a human that's been flying 4-6 sectors 12 hour day for 6 days starting at 4am for the first two then 2pm for the next two and 10pm for the next. 36 hours off then repeat. The responce of even a well trained individual varies hugely from day 1 of a block to the last sector. You have to design for that last sector. Try that schedule yourself for a month then go sit a car driving test and see if you pass. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I suppose one solution could be to mandate increased recurrent training on type by say two additional sessions per year at cost of 33 600 euro per aircraft and 4 days lost from flying the line for each pilot. And reduce the max working hours that can be flown on the type by say 2 hours per day and say down to 800 hours per year instead of 900. Oh and so we don't have a 10 billion dollar hit to our company again due to foreigners they will have to do an extra test every three years with an external Boeing approved examiner. This will need to be done in a hydraulic powered SIM which is the only type which has enough grunt to simulate the max when it's in crazy Ivan mode, The electrical actuated Sims don't have enough power. Oh there is only two of them and your pilots will have to be able to get a US visa to be able to use them. That would solve the issue. Pretty much put every Boeing short haul operator out of business within two years. Save a fortune in booze at airshows everyone would be laughing walking past your enclosure.. muttering they should have opened up the 757 line again and stuck the leaps on that. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Gee, I hope those pilots never encounter weather on their last sector. That would be terrible. From now on I'll ask the gate agent which sector the crew is on and bail if it's the last one. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I suggest you do. It's usually a factor with runway excursions. Last sector shitty weather, pissing down with rain, blowing a gale the pilots want to get home don't want to divert and all the Hassel that's involved in that. Anyway they would miss thier jump seat ride home and would have to pay for a hotel room if they were a regional operator in the US. See the dash crash report for a typical regional pilots life style. Approach goes unstabilised they don't go around Vref +30 over the numbers contaminated runway...and off the runway they go at relatively low airspeed so nobody gets killed. https://www.washingtonpost.com/transportation/2019... There is usually 5-10 a month going off road globally depending on the season. It's just as likely to happen in the US as anywhere else. To be honest if your going to go off runway the 737 is the aircraft to do it in. They have done it so many times over the years and very few killed. Pull them out the grass NDT the gear swap any engine that's sucked mud, light fires and go flying again. You can turn them round in under 12 hours if they have gone into the retard pit. More enlightened company's change the crews every day so when your on your last day of a block the other pilot is on there first day. This causes a major increase in crew planning load. So alot of airline's block roster so pair up a crew and then plan them as a unit for the block. Which gives you the crew at the same fatigue level on the last day. Plus more than likely fed up with each other after having spent 12 hours day with 3ft of air between you for 6 days. Which just adds to the mix for the Swiss cheese holes to line up. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] An airline we all know that doesn't skimp on training, maint is top notch. Has world class top employee relations with crew. No excuse it's was poorly trained foreign crew. They are all 3000 plus first officers and 8k plus captain's. And in the retard pit. http://avherald.com/h?article=4c1378c5&opt=0 Have a look at the news listing it proberly only picks up about 10-20% of the minor stuff like lighting strikes and bird strikes that cause damage. Fumes and the like 50% and 90% of the major stuff. See for yourself how many runway excursions are occurring. Never done it myself yet... But until I am permanently grounded I will never say it won't happen to me. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] It's 2000 meters and 33 meters wide. More than enough full flaps for a decent properly trained crew with an arse covering grumpy auld captain in the left hand seat who can apply appropriate risk assessment with no recourse for thier command descions. And I have never heard any pressure for southwest crews. They really are a top notch airline It just renforceses how lucky I am at work. Had a discussion the other day on ops Freq with the dispatcher about a fueling issue and when I was at the loosing my rag point of getting the technicians to the aircraft to dip the tanks or fill the witch up to 5220 kg full so I knew what was in the tanks, A voice was heard saying dispatch do as you have been fing been requested by the captain. Report to the chief pilots office at 7am Monday for debrief. A clinical German will be re-educating said dispatcher and their boss if the email I received on the subject will occur. It was the flight ops director doing a C of A test flight with caa test pilot on board who heard my frustration. Alot of other pilots are not as lucky as southwest pilots or me. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] And wet, with a tailwind. And apparently over-weight. Poor judgement to not divert. So how does an Ethiopian pilot blow a runway twice the length on a nice day? It's long enough to land, stop, and take-off again without turning the plane. And they still put it into the weeds. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Same as Airfrance killing Concorde off. First world nation. All pilots done the 6 year aviation degree, 4 years training thousands of hours on the line on the premiere fleet still screwed it up.... The fo had more hours than most 737 cockpits crew combined. Over weight, tail wind, third set of eyes in the cockpit with zero role flying the machine still everyone dead as a dead thing. But then again a US military crew managed to bang in a C16 into Coco beach in cavo on a 1800 meter runway while talking to a tower 20km away and didn't go off the end of the runway.... RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Remember that this is the Engineering Failures & Disasters Forum. The ET302 final report will almost certainly be focused 80%+ on the aircraft design, its certification and all that surrounds it. It's huge, vast, industry changing. It's therefore a bit odd to characterize the MCAS design flaws as merely being "a problem", while using the adjective "glaring" to describe gaps in pilot training. The crew responses are certainly a contributing factor, and worth perhaps 20% of the report. It'll be interesting to see what conclusions are reached about the design of the aicraft itself (the user interface) being a contributor to those responses. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Lionair report will be out first in about 18 months time. Hopefully though the FAA and congress though will have sorted things out before that. And their solution to the whole certification and training will be acceptable to the other WW aviation authorities. To note though everyone is focusing on MCAS. The whole power of the trim stab V elevator and using the trim stab to sort out any issues with the flight envelope, which also links in to what's an acceptable authority of the manual trim system if the trim stab is used needs to be addressed. Then if it is used what level of redundancy and critical flight control system certification is required on anything that has an input into controlling the trim stab. Changing a few lines of code is not going to get the max flying again outside US airspace. And I can't see the FAA releasing it until the other authorities are happy. Oh and the days of a A319 pilot being able to walk across the apron and jump into a A320neo are numbered as well. So its not just a picking on Boeing thing all the OEM's are going to be hit. The NEO apparently has some handling differences on rotate which can catch people out. Possibly leading to tail scrape. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I have a question concerning the need for the new planes. Of the grounded planes, how many were needed to service increased passenger numbers and how many were replacements for older less efficient planes? How many flights have been cancelled and how many are being serviced with the older planes at the older ticket prices. There is no question that the airlines are taking a big hit after paying for aircraft that they can't use. Apart from that, how many flights have actually been cancelled and how many will be serviced with existing (and paid for) aircraft. I suspect that the impact on ticket revenue may be less than we have been led to believe. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Well, from a personal aspect, I had a vacation for booked in January to Peru and Mexico in June on airlines that use 737 and similar size aircraft. Just days after the 737Max grounding, Travelocity notified me that my itinerary had been rearranged due to flight cancellations. The Plan B itinerary created by Travelocity and/or the airlines was not acceptable, but fortunately, through consultation on the phone with Travelocity, they proved to be very helpful and accommodating, and came up with a Plan C itinerary that was just fine, and with no change fees on my part. FWIW, on 5 flights so far out of 6 flights total, 4 were nutted (i.e. completely full). "Schiefgehen wird, was schiefgehen kann" - das Murphygesetz RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] It depends on the company. You won't get true numbers on the subject to be honest because its market price sensitive information which may change the way the airline gets credit on spare parts and fuel. Most airlines plan there routes at least 6 months in advance and put the seats on sale. Commercial will have the list of aircraft avaiable and will plan for that. If an aircraft is due to be delivered then they will plan for its use a week after its meant to arrive but could be less. Now if its a fleet expansion then if it doesn't turn up they will wet lease in another operator to run the routes until the aircraft is avialble. If its replacement then the aircraft its replacing will be due to go back to the lease company on a certain date. If you have a pesamestic planner they will have some breathing space built in. If they arn't it could be the old aircraft will be due to be returned the day the new aircraft comes into service. Now when you return an aircraft you usually notify the leasing compmnay 3-6 months before the event and then the leasing compnay sells it on as a "live" aircraft to another operator. A live aircraft gets a better hire rate than one thats been sitting for even a month so once you have told them that's it. Now there are other costs involved as well. You will recruit and train for the new aircraft approximately 3 crews per aircraft so 6 pilots and 12 cabin crew and 1 technician so @200k . In europe anyway their salarys will have to be paid even if they don't fly. US they just get kept at home unpaid. Aircraft don't sit on the ground for free you have parking and maint costs. The technicans will have to do checks on them every 48 hours and do engine runs when the engine OEM says so. They can go into long term staorage mopde which cuts this down but it cost money to put them in and takes 2-3 days to take them out. BY the looks of things in Europe they are all in long term storage now. Currently in europe the companys that bought them for expansion are laying off crew. Airlines who are replacing have suspended recruitment. Even to the point people have resigned from current jobs with start dates and the day before they were due to turn up they got a phone call saying don't turn up tomorrow. As for covering the routes there is an utter lack of cover now and the price of a wet lease has gone through the roof and several companys are making a fortune out of it. Also in the EU if the flight gets canceled due to no aircraft then the airline has to pay compensation to the tune of 400-600 euro per flight per pax. All the max operators have basically soaked up all the wet lease spare capcity in europe now. So if an aircraft goes tech there is basically nothing to cover it. The boys and girls at TItian are flying their bums off (Titian makes its buisness out of short notice save the day wet leases). The ones that are replacing this winter or next year have bigger issues. The current aircraft may need to go into heavy maint if the lease is extended which will remove them anyway for 1-2 months and cost loads of cash plus all your budgets are going to get blown out the window. If you send them back all your sales for next summer season are out the window all the spare capacity is gone with the companys that have planes delivered. Come septemeber a load of airlines will go bust which will help but won't solve the issue. As the ticket price is linked to market demand then across the board prices will rise and it doesn;t matter if the airline is a 737 max operator or not they take the market price. So expect prices to rise as airlines charge the market rate for demand meets supply. As someone else said in these threads basically half the supply of single isle medium haul aircraft is currently suspended world wide. And there is no supply to replace the demand at what ever price, the production is spoken for for the next 6 years. So world wide they have to get the MAX flying again. Quite what they are going to do about sims I have no clue... It takes 18 months lead time to buy a sim. If they have to develope a hybrid hydralic electro sim to be able to simulate control forces on the MAX then 24months. They will have to get something like 3000 crews through training before airlines can start using them again unrestricted. Even if they can use the current NG sims to do it its going to take months with every NG sim in the world running 24H which they pretty much are already. Currently there is one full motion sim in the USA with MAX flight dynamics programmed and apparently its electro servo and can't produce the control forces that you need to simulate a MAX going crazy Ivan. Ticket revenue I expect to increase hugely for none max operators. Those who have leap engined aircraft types will be getting huge returns on there capital. To be honest this is an engineering disaster and failure but its going to turn into a huge Economic disaster for the whole industry. And the pax will pay for it. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Thanks for the background, Alistair and thanks for sharing your re-booking experience Hemi. Another question: What is the feasibility of fitting the original engines in place of the Leap engines on the aircraft that are already built? That may avoid some bankruptsies by getting the seats back into the air. Bear in mind that without the Max, most of those airlines would have been in line waiting for the Airbus product. Yes, there will be a cost. However the cost may be a small fraction of the alternative. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Oh my... "Schiefgehen wird, was schiefgehen kann" - das Murphygesetz RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Weren't the new engines one of the primary selling points of the MAX? Going back to the old engines makes the MAX a bigger fuel guzzler. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Another rushed or half-baked cobbling of engines and airframes is likely to result in more accidents. Better the beast that we know. The fastest/safest solution will include hardware changes to the MAX such as redundancies for the AOA sensors, training, and whatever else the experts deem is needed to put the MAX where it should have been from the beginning. If the public trust won't accept that then it sounds like Boeing is in for some dark days ahead and we will all be paying until new equipment rolls off the assembly line. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I wonder how much the "Substantial discount" was that BA/IAG got??? https://www.theguardian.com/business/2019/jun/18/b... Delivery 2023 so they will assume it will all be sorted out by then.... Remember - More details = better answers Also: If you get a response it's polite to respond to it. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] (OP) Quote (Alistair Heaton) As someone else said in these threads basically half the supply of single isle medium haul aircraft is currently suspended world wide. And there is no supply to replace the demand at what ever price, the production is spoken for for the next 6 years. So world wide they have to get the MAX flying again. And yet, I know of one aircraft lease company with serviceable CRJ's still parked on the ramp... Quote (Alistair Heaton) can't produce the control forces that you need to simulate a MAX going crazy Ivan. Isn't the 737Max actually attempting to do an "English Bunt" or an "Outside Loop"? The Crazy Ivan being more of a horizontal maneuver... No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it. STF RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I can see where your going with crazy Ivan being horizontal. I think someone started using it because it was a sharp change of direction and alot of us were waiting for the conspiracy theorys to start that it was sabotage by a certain country. Crj doesn't have the range or the capacity to replace a 737. You would need two of them. In Europe it's a not very common rating for pilots to have. The transfering on to the easa reg can be problematic and expensive depending on the fit although crj is 1990 so might be not to bad. They should all have egpws and TCAS. Crj 100 pax 1600 mm 737 160 pax 2600 nm. The range isn't really an issue but the loosing 60 pax at 600 euro a head when they paid 300 euro a ticket is. So they get refund plus 600 for two sectors so call it 20k per sector lost for using a crj instead of a 737 before you add in the cost of the wet lease. 8 sectors a day 160 000 EUR per day ... It's cheaper using a twin isle on short sectors and keep the Ng on the long routes if the runways are long enough both ends. Plus no issues with movement slots. They need aircraft crew and maint and AOC through the correct authority for your area for wet lease. But come September then commercial will have a different plan for the winter season. Just now is fire fighting, September they will have a different plan. There will be the aircraft that are grounded over the winter to be used so the pressure will be off. Then they will have to decide what to do next summer and if its likely the max will be flying again. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] IAG is just a letter of intent no money has changed hands or airframes ordered. Willie is right it's in nobody's interest to have only one supplier of airframes. BA won't be taking them. It will be Vueling I suspect. And I personally just thought here we go another 15 years of legal nonsense about selling for less than cost price with the price they will have got them for. All the Boeing legal tricks will get thrown back in their faces with gusto. Wasting money and oxygen talking nonsense when everyone is as bad as each other and doing the same thing. Money spent on lawyers that could have been spent on engineering and tooling. Old engines are not an option. The leap engines are giving outstanding fuel consumption. We are talking 1600kg an hour compared to a 737-500 at 2300 kg an hour in the cruise. And to be honest mcas has highlighted other issues with the NG certification so just changing the engines isn't going to get it flying again any quicker. The A321 XLR 757 replacement order in the US is more interesting that IAG's letter of intent to be honest. Boeing have bet on twin isle aircraft with the 777 so have nothing to take it on. 100 tons capable of crossing the pond it will open up loads of regional airports for transatlantic. I am sure there are loads of routes in Asia it will be good for. The likes of easyJet will be able to go long haul with very low training costs and a unified short/long haul roster the savings are collosal. The Chinese of course will be flying them about at FL200 using the fuel to do normal sector lengths. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] A good article detailing the history of how MCAS got to where it was in the production models. I suspect that 3 seconds is going to get changed. BUt to be honest with all the alarms going off you could give it 30 seconds and still not be assured that the pilots would locate the core issue. https://www.seattletimes.com/seattle-news/times-wa... RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] The sequence of how this unfolded (as described in the Seattle Times article) is sufficiently subtle and complicated that fixing the design and certification process itself is going to be a huge challenge, and probably a very lengthy process. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Another takeaway from the article would be that reversion to using both AoA sensors and possibly additional sensors info for more accurate detection of stall could minimize the activation of MCAS in the first place. There's also the question of whether MCAS is overly aggressive, but that's unclear because the two examples had erroneous excessive AoA indications. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] (OP) Quote (IRStuff) There's also the question of whether MCAS is overly aggressive, but that's unclear because the two examples had erroneous excessive AoA indications. It's for the very reason that the system wasn't thoroughly certified that we don't know the answer to that question. A proper system safety analysis would start by classifying the hazards the system is meant to address, and then reveal the hazards posed when the system fails to function. I've attended these "system safety murder boards" before (not as a chief but only as a participant) and it seems like being cruel and unforgiving is the way to do it right. No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it. STF RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] "cruel and unforgiving" No doubt. Assuming the article is mostly correct, MCAS was further hampered by forcing it to do two different things, essentially using the single AoA sensor. Clearly, serious errors were made in the safety analysis that allowed that to happen. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] But it also uncovered the extremely small window that the manual trim system will work with your normal pilot strength without having to go for aerobatic rollercoaster procedures to unload the trim stab. Which somehow managed to get through when the 800 was certified more than likely by the same process. That said it would take a system failure followed by flight upset to get out of that window, without another system input. Just have a look at the 800's elevator compared to other types, its tiny compared to the Stab. 6m2 v 32m2 Also the "average" pilot has changed since the 60's. It is not uncommon now to fly with 60kg females. They do struggle with the older types without power assist controls. Powered no problem. Maybe they are having to move MCAS from controlling the stab to controlling the Elevator aka a feel system type input to stick force. So if anything has air data sensor input it needs to go in via elevator otherwise they need to change the relative sizes of the Elevator V trim stab. I can't see how they can turn down the gain on the MCAS system as it was there to sort out a flight envelope certification issue. Its either needed or its not... We can be pretty certain it is required just as STS was required to get the 800 through. They started out with a relatively slow small input and ended up with a lot more due to the aircraft not being certifiable without that input for an extremely small seldom explored part of the flight envelope. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Aside from turning down the gain, there are a number of other things that can be done, including making sure that it doesn't activate when those specific design conditions don't actually exist. The while reason these threads exist here, and we're discussing this issue, is that MCAS activated twice when it wasn't supposed to. What happens when it activates when it is supposed to is another, separate, matter; that requires some understanding whether the multiple activations actually make sense, particularly in the context of the infamous 3 seconds. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] It seems arguably obvious to offer an MCAS cutout switch, separate from the electric trim cutout switch. But then 'MCAS' would have to be mentioned, and trained. And they'd need to prove that such a change to the cutout switches is actually appropriate. But that involves admitting all the previously discounted failure modes. Such a hardware change would thus slow certification. But it might be considered to be essential by those now more wary of software having such authority. Or relying on software to limit its own authority. An approach that might not be accepted. The certification phase will probably dominate the schedule. 2020 won't just be hindsight; it must be figuring in the schedule by now. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] What's your views on the trim stab window of airspeed and pilot manual recovery using the wheel? And the relative power of the trim stab V elevators? And the sensibility of allowing anything to control the most powerful control. Per say if the Elevators were driven full deflection you could still recover relatively easily and land the plane using the trim. We know what happens the other way round. To me you need to get the rules concerning the base systems sorted, only then you can fix the secondary and tertiary systems. If they put in a secondary powered trim system which created a larger window for recovery that would change the "status" of the manual trim system relegat it to tertiary backup which the small recovery window could be acceptable for. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] "Per se" = "of itself" We know that when the elevators are at full deflection it is difficult to move the stabilizer; that was the primary problem. High elevator loads overpowered the manual control of the stabilizer. The powered trim worked. The pilots chose not to use it to offset the MCAS inputs. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] The pilots on Ethiopian Air did use it (electric trim) , just not all the way back to "neutral" before they pulled the contacts. The AD was unfortunately rather vague on this with a "can be used" and also gave the now false impression that manual trim control could be used at any time. Then when they tried to use it again they were going so fast that the rather brutal movement of the stabilizer made them hesitant to keep on using it. Then MCAS kicked in again, lifted them off their seats with negative G and they couldn't correct with elevator trim alone. It's interesting to note that in any of the scenarios listed which were looked at during design / certification, they don't really seem to have considered what else happens if your AOA signal goes loopy, e.g. the stick shaker, alarms, discrepancy of instruments etc and still think the pilot is going to work all this out. It was only by having a third pilot in the Lion Air plane on the flight before the one that crashed that spotted what was happening and recommended the correct course of action. I think alistair has hit the nail in terms of what might be going on in looking at whether the design really should be other way around for elevator vs stabilizer conflicts given the disparity of surface areas. Remember - More details = better answers Also: If you get a response it's polite to respond to it. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I wonder if the time spent on MCAS would have been better spent finding ways to mount the engines under the wings. With a billion dollars and a month or so, I am sure that the problems of under wing mounting could have been solved. In hind sight, a billion dollars and a few months would have been a lot cheaper than the alternative. Sure there are lots of problems. When faced with a difficult problem, some walk away, some try harder. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Just as a reminder of the chart for the Ethiopian flight. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] "they don't really seem to have considered what else happens if your AOA signal goes loopy, e.g. the stick shaker, alarms, discrepancy of instruments etc and still think the pilot is going to work all this out." This is the big issue, and something which will have to be looked at and we will only know what went on when the CVR is released. MCAS is only the system which has highlighted other issues. Your in theory meant to have at least double redundancy on all critical systems. ie the ones if they go wrong will kill you. Triple redundancy if possible. "We know that when the elevators are at full deflection it is difficult to move the stabilizer; that was the primary problem. " Its impossible to move the manual trim wheel at elevator deflections under half deflection and full forward trim cannot be overpowered by full aft elevator. Stick forces increase by 50lbs per 2.5degrees out of trim. And your right for certification it is now the primary problem. There is no redundancy at all for the electric powered trim system across the full range of the flight envelope. Boeing deems the pilot to be the backup system as long as they react and sort out what the hell is going on in under 3 seconds. Once your outside that under 8000ft agl your dead. Basically in the time it takes you to read this post. With the stick shaker going, egpws giving it don't sink, airspeed mismatch and finally the overspeed alarm as well. I think you can see on the chart when it was likely both pilots were pulling on the stick at the end. MCAS and how its programmed is a side issue now. What training the pilots had and if their reactions were correct are a discussion point. But until they sort out the trim and elevator system and get it safe with redundancy across the full flight envelope it can't be tackled. If the manual trim had been able to be used across the full speed range nobody would be dead. It can't so there is no redundancy in the trim system. BTW the MMEL says you can go flying with one of the electric trim switches unserviceable. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] BTW my one is different the second line up on the right has control input. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Duly noted; and so edited to reflect a similar image. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] that write up is chilling.... And has a ring of truth to it.... RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Spending a billion dollars on re-designing wings or engine mountings is silly if a <$5k device is going to make the plane porpoise like crazy because it's pinned to rails. If the AoA sensors were working correctly or corrected with other data, MCAS wouldn't have been activated at all, and if the AoA sensors were working or corrected with other data, MCAS wouldn't have repeatedly activated. The "primary" problem is still the AoA sensors; they had redundancy that wasn't used, but the raw failure rate is what's truly at issue.

Had these flights gone through what MCAS was designed to fix with working AoA sensors, it's likely both planes would have survived, since they wouldn't have had conflicting information and they wouldn't have had MCAS repeatedly activating, since the first activation would have produced plausible AoA responses.

TTFN (ta ta for now)
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RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

As A. Heaton noted above, the 23 jun Seattle Times article is informative on how the design of MCAS evolved during production,, apparently without review by the originating designers. It yet remains hard to believe that the engineers that originally limited the MCAS max degrees of declination did not know this limit was later greatly increased ( to account for low speed stall) and that the use of backup sensors was deleted. To have the lives of 200 passengers dependent on the reliability of a single sensor makes one wonder at the possibility of other gross errors that slip by the "regulators". Perhaps the use of multiple sensors for this anti-stall function was patented by airbus??

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Yes but they have the trim system dynamics to deal with now. So a third AoA vane and a new box of tricks ain't going to get it flying again.

I would say MCAS is now a secondary issue.

Plus the rest of the certification will be looked at.

This isn't a solve one problem get a tick in the box and fly again.

Once its recertified then the training to fly it will start which will cause other issues.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Hi IRstuff;
Where we disagree is what is/was the primary problem.
Using the five whys approach may take us back from the MCAS system to the engine placement and the resulting unacceptable flight characteristics resulting from the engine placement.
The real cost of that <$5k device is now being counted in the billions and hundreds of lives, and by, the way I understand that the wings were redesigned to withstand the new forces caused by the forward engine placement and the greater mechanical advantage of the longer engine pylons. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Why doesn't the A 319 Neo need MCAS? Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Because the A319, and all Airbus AFAIK, don't allow any feel for airplane controls to the pilots. If the actuators fail, people die. So they build a big pile of redundant actuators into their planes and a big pile of redundant sensors (which hasn't always helped.) Note that MCAS doesn't operate during autopilot operation because the autopilot won't let the plane get to the high angle of attack. In that way, the fail of the autopilot on the 737 is also due to depending on AoA measurement. This lack of feel is what let AF447 drop like a stone into the Atlantic and another one rip the vertical stab right off the plane from rudder pedal inputs. There is a basic difference in philosophy - Airbus believes the plane needs to be protected from the pilots; Boeing believes the pilots should have the most direct inputs. In both cases when the plane has a problem it is possible for inept pilots to become exposed and everyone dies. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I thought the reason it didn't need a similar system to MCAS was the plane naturally sat higher, resulting in the larger LEAP engines sitting in the previous engines place; this meant it doesn't have the thrust angle issue that the Max has? RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Because the engines sit in more or less the same location as before. So no major changes to the aerodynamics. Remember - More details = better answers Also: If you get a response it's polite to respond to it. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Any differences in Airbus aerodynamics is 100% hidden in the same control system that hides all the other airplane performance characteristics from the pilots. The entire Airbus lineup is 100% MCAS 100% of the time. Just with more redundancy. There is no thrust angle issue (where does this stuff come from?) as the engines have less moment arm from thrust than previous 737 engines did and the engines are still basically parallel to the fuselage. The larger diameter lets the engines produce similar amounts of thrust with less fuel burn; they aren't supposed to produce more thrust. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] It is not the engine thrust, it is the aerodynamic uplift on the physically larger engines at high angles of attack. Not much of a problem with the engines under the wings. It is a big problem with the engines out ahead of the wings on the longer pylons. It was the engine location which caused the flight characteristics that MCAS was supposed to remedy. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] The AP will let the plane into high angle of attack, but when the stick shaker triggers it then should dump the whole lot onto the pilots to sort out when the AP cuts out. Well in theory because in these the AP stayed in with the stickshaker going which also needs dealt with. How to get the AP to command high Alphas is easy you just put it into VS climb mode and set a high rate of climb and don't do anything, eventually the plane will stall and kick the AP out. The altitude you stall at depends on the rate of climb. If you use the level change or ASI then you have protection. You can also get it in ASI mode if the pitot tube is blocked to the active ADC supplying info to the flight director when that happens the ASI turns into an altimeter and the aircraft will pitch nose up to try and maintain a fixed airspeed which will always increase with altitude so the nose just gets driven higher and higher until the stick shaker goes off. Then your dumped with an aircraft with about 40 degs nose up with full power on and full aft trim. The airbus has a different setup. 737 is a single electrical screw jack. 1 actuator. Airbus is 3 separate electrical motors then the mechanical trim feeds in from the front (two sets of steel wires one down the left of the aircraft one down the right). This then feeds into twin system hydraulically assisted screw jack one of which is powered by the redundant third backup hydraulic system that's powered when the RAT is out and the other by the one of the main hydraulic feeds. So triple redundancy on the electrical side of things and dual redundancy on the hydraulic, dual on the mechanical linkage. Full range of elevator travel is available to the pilots at any speed or any degree out of trim via the manual trim wheel. I believe the 777/787 has a similar setup. AF447 you are completely right it was extremely poor command decision to leave the FO in charge while traversing the ITCZ with the cruise SO flying the aircraft and go to your bunk. Their actions after that again surprising. Basic power pitch equals performance not followed, exercise 5 in basic PPL training. But again they were all first world nation, national airline, 6 year aviation degree, 4 years of training then type rating and into an aircraft selected from the cream of the population certainly not your average intelligence for a pilot or for that matter average amount of training. AA587 was again bad training but this was more understandable as it was a national issue. In the US the pilots were taught to deal with flight upset by lifting the wing using the rudder pedals. So when you get a wing drop you press the opposite rudder and use the secondary control effect to roll the aircraft instead of using the Ailerons and roll. And you do get force feed back through the rudder on airbus. Not on the stick though because it has autotrim on pitch and roll to keep attitude when you release the stick. So the FO trying to use the rudder to fight huge roll effects from wake vortex cyclically inputed full rudder deflection. The tail survived I think 6 cycles and the eventual failure stress was calculated at something like 4 times the certififed failure load. Afterwards all OEMs put a warning in the manuals about cyclic inputs and NASA did a load of studies on it including the US stall procedure and reported to the FAA that things needed to be changed. The FAA changed things but both methods are still being taught. There is a conspiricy theory that the FO couldn't be strong enough to push the rudder pedals to full scale which sort goes against the claims that there is no control feed back forces on the airbus. I had a FAA trained US passport holder FO rip his hamstring off the bone due to trying to use the rudder to lift a wing with a second generation yaw damper still engaged trying to lift the wing in similar circumstances in Saudi. We couldn't even get him out the cockpit in the air so he was screaming like a banshi for 10 mins until i could single crew it down to the ground and land. And no morphine to boot in Saudi!!!. So i can completely see a adrenaline fueled push of the pedals by a thousands of hours ex military pilot being able to go full defelction if a young lad can rip the muscle off the bone pushing against a rock solid yaw damper controlled pedal. His mistake was not pushing the AP disconnect button twice before pushing on the pedal. After he started screaming I corrected the attitude using roll without touching the rudder pedals. That was in 2012 and this AA587 happend in 2001 and he had been flying for 2 years so this nonsense is still being trained even with NASA and the FAA telling people its the wrong way to operate. He was put on a plane back to the US saying he was going to sue BAe for a bad design because he had carried out his training correctly. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Quote: The engine was moved slightly forward and higher up…which changed how the jet handled in certain situations. The relocated engines…caused an upward pitching moment. Boeing added a new system “to compensate for some unique aircraft handling characteristics" I thought it was common knowledge that the 737 engines had to be relocated due to their size; while the Airbus version didn't need to relocate their engines. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I recall that airbus had a crash about 10 yrs ago ( brazil to spain??)due to reliance on a single pitot tube, maybe that tragedy led to the increased redundancy now evidenced in current designs. The lack of reducndnacy on some fighter jets may also be the reason why airfields that host fighter jets need to police the field for debris before allowing the fighters to launch. "...when logic, and proportion, have fallen, sloppy dead..." Grace Slick RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] No they had triple redundancy with pitot tubes. That's af447 your on about. All commercial aircraft have triple redundancy of basic flight variables. The only one that doesn't is the TAT probe which isn't mission critical. Even the dc3 has three pitot tubes. They iced up after flying into a collosal thunder cloud and there was an issue with one of the heating elements on a pitot tubes. They then made a complete and utter hash of procedures and killed everyone. The pitot design was changed but that was it. Less than 10% technical mostly pilot error. Which to be honest is normal. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] There may have been an attitude at Boeing that may be mirrored here. Once a design decision has been made there is not time to re-evaluate the decision. To take sales away from the Airbus Boeing needed a plane with the Leap engines. The first indication that they may have been going off the rails was when flight simulator testing showed the unexpected lift generated by the engines at high angles of attack. Quote (Paraphrase of a number of responses ) A flight simulator does not have to simulate flight outside of the normal flight envelope Boeing's flight simulator was good enough to show up this problem. Well, now a problem has been identified and we need a solution. Maybe that was a bad decision to put the engines in that position. Maybe yes, maybe no. But neither Boeing nor some posters here will allow that decision to be re-evaluated. How many here have seen a an attempt to fix a bad design with a kludge. Sometimes the kludge results in more problems. Eventually kludge upon kludge results in a solution that sort of works, but not as well as it could. Going back to the original design decision and changing that may result in much better performance all around. The problem arises when someone refuses to allow the original design to be considered. Attempts to explore possible alternatives here are quickly shot down. A suggestion that longer landing gear would have allowed the engines to be placed under the wings was shot down. Quote (Paraphrased) If the plane was higher off of the ground there would be difficulty loading the luggage That may have been an issue 40 or 50 years ago, but most luggage is now loaded with a conveyor and the MAX is competing with a plane that is higher off of the ground and that has the leap engines fitted under the wings. Quote (Paraphrased) Longer landing gear would have to be re-certified and the wings may have to be strengthened. There are reports that the wings were strengthened to withstand the added force and torque generated by the forward engine placement. I hope that these changes were certified. Quote (Paraphrased) Longer landing gear could not be stowed in the existing wheel wells. But when a potential tail drag issue was identified on the Max 10, Boeing tried harder and developed an extending landing gear for the max 10 that gave them the needed clearance but could still be stowed. Quote (Paraphrased) But the Max 10 landing gear only extends on rotation. Try harder. Boeing tried harder once, maybe they can do it again. Quote (Paraphrased) Changes to the landing gear would have to be certified. I hope that the extending landing gear on the Max 10 was certified. It would be nice to have a discussion in regards to possible alternative solutions without every suggestion being shot down because it is not MCAS solution. My suggestion that the existing Max aircraft be fitted with the original engines in the original position was not intended as a final solution. Quote (Paraphrased) changing engines and engine location may lead to more problems and issues. A year or so ago I doubt that this position would go unchallenged. Now, given the mistakes, bad judgement, oversights, forgetfulness and response to the Max issues, the thought is gaining in credibility. The suggestion to change the engines was intended to be a stopgap measure to get seats in the air and to limit losses. Compare the cost of unavailable flights and penalties and refunds or the cost of using charters to fly those flights with the cost of doing business at last years fuel cost. Since making this suggestion I understand that the worst crisis will be over when the present flight schedule ends. Subsequent schedules will factor in the shortage of aircraft. This may still turn out to be the best financial solution if things don't go well with the international authorities. When the Max finally flies again, these planes could be scheduled for rotation back to Boeing for the upgrade. Eventually when all the existing and future Airbus orders have been filled a couple of years from now, the operators of the older engines will be at a disadvantage. At present there may not be much disadvantage as much as the operators with Leap will be reaping windfall profits. It has been reported that ticket prices will be high in the near future due to a shortage of seats. All flights will be doing well financially. A shortage of seats means high prices and full aircraft. The Leap operators will be doing VERY well. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Changing the engines won't help the MAX, since it won't be any better than the existing models, which already have the same engines. The high demand for MAX basically shows that the buyers want the LEAP engines. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Increasing the gear a few inches is not the same as increasing the gear several feet. The existing 737 ground equipment works with the new 737s, not Airbus The existing 737 pilot training works with the new 737s, not Airbus The existing 737 maintenance management works with the new 737s, not Airbus What production line is tooled up to make the old engines in quantity? Making a move to Airbus would wipe out airlines like Southwest that has specialized in 737s. Every solution that isn't MCAS is building a new plane and scrapping the 737 cockpit, increasing the ground, maintenance, pilot training, and other costs. Sure, the aluminum can be recycled as scrap and the seat rails and seats stored for the next generation, but I don't see Boeing as reconfiguring the cockpit with large trim wheels so a 1 percentile pilot can crank the stab at Mach .6 from more than 2 units out of trim. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] For operators faced with a shortage of seats, there may now be more pressing issues than "helping Max". The operators facing equipment shortages will be looking at alternatives to the Max, if only for the short term. They want Leap engines but they can't have Leap engines right now. Airbus has a pretty long waiting list and we don't know how long it will take to get the Max approved. If the wait for the Max turns out to be much longer than anticipated I am sure that some operators will be running the numbers on an engine swap. Putting last generation engines on the Max airframe leaves the option open for a later upgrade. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] The problem extends to the NG as well and maybe earlier planes. That's what is taking so long. For a similar trim runaway, managed as poorly as Ethiopian Airlines did, the NG will also crash. Eliminate MCAS as a potential accident initiator and the Max is no different than the NG. There just haven't been any trim runaways for pilots to face or, if they have happened, they happened to crews who dealt with them correctly. Again - where do those extra engines materialize from? RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Quote: Its impossible to move the manual trim wheel at elevator deflections under half deflection and full forward trim cannot be overpowered by full aft elevator. Stick forces increase by 50lbs per 2.5degrees out of trim. Well, it can be (at least mostly) if you don't overspeed the plane.... Which brings up another question. The stick feedback appears to be hydraulic so why not reduce that force? The 737 being an old fly by cable design doesn't have electrical systems redundancy because the cables are supposed to be the redundancy. It doesn't appear to have any redundancy for the instrumentation side to side so a single AOA sensor failure throws off a whole bunch of stuff on that side. Bill - Doesn't Max 10 gear just lengthen on rotation? I'm thinking it was a very specific design to keep the forces in the gear equal to the old gear design. Otherwise, why didn't they just make new gear that was extended all the time while deployed and only retracted when stowed? I doubt the old 737NG engines are available in production quantities anymore. The Max planes are being ordered because of the fuel savings. Airbus has way more than 2 years of neo orders. There is probably about 8-10 years worth of orders. You also got one paraphrase partly wrong. The 737 was originally designed to sit lower to help with loading luggage and passengers, which became an issue when fitting bigger engines. Lots of planes use fly by wire controls. So, why does the proper fix have to be a kludge? RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Good points Lionel Quote: Which brings up another question. The stick feedback appears to be hydraulic so why not reduce that force? I can make a suggestion; Anecdote alert. A few years ago I had occasion to move an older truck, one of the first models with power steering. Things went well until I made a sharp turn into a driveway at low speed. The early versions of power steering added assist to basically manual steering. It took about twice as many turns of the steering wheel as I had expected. Over the years the steering ratio has been reduced. You no longer need a lot of mechanical advantage because hydraulics are doing the heavy lifting. Anecdote off. Had the artificially generated control forces been dialed down incrementally over a span of years it may have been acceptable. But I don't think that it would be a good idea to abruptly change the control force feel from similar aircraft. Imagine a pilot moving from one plane to a similar plane but the control force for a given result is only half of what he is used to. I don't see any technical problem to reducing the stick force feel, but there may be insurmountable problems with usability. Quote: Doesn't Max 10 gear just lengthen on rotation? That is my understanding. I was probably unclear with my comments. Boeing tried harder and came up with the extending gear to avoid tail scrape. I am sure that there were problems to overcome. My thought was by trying harder again, an extending gear may be developed that will both give the needed clearance and still fit in the available space. I'm out of time just now. More later. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I meant helping MAX in the sense that if someone has to choose between a rebuilt/redesigned MAX vs. Airbus, particularly if the MAX won't provide the promised fuel savings, then the MAX is essentially dead as a product; everyone that needs seats now, or within the next couple of years, will be more than willing to get an Airbus, if the delivery is not substantially longer. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Satcom guru has done a search for trim events. Its more common than I thought https://www.satcom.guru/2019/05/737-pitch-trim-inc... "It doesn't appear to have any redundancy for the instrumentation side to side" All commercial aircraft have redundancy side to side via the standby instrument as minimum. When a mismatch occurs the standby instrument is consulted and then the two out of 3 win and things are reconfigured to only use the deemed good side in none FBW aircraft. How the FBW aircraft do it I have no clue. "Lots of planes use fly by wire controls. So, why does the proper fix have to be a kludge? " Because that would bust the grandfather certification and if they made them go through a full FBW certification of the flight controls then the max won't be flying for at least 3 years. It has to be a kludge that walks a very fine line between not triggering recertififcation and complying. They are working with both hands tied behind thier backs and one leg with a ball and chain on it. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Interesting trim events and to note that the earlier 737 had two actuators. and my reading is that the cut out switches on the NG were split manual and FCC, whereas the Max went for primary and standby, or something like that. Is one option here to revert to that design and make the cut out switches separate for manual and automatic (FCC/MCAS). Then in the event of runaway from any source other than the manual switches, cut out the input to the trim motor from the FCC, but allow the manual pilot trim buttons to remain and hence address this issue of manual wheel control unable to turn against the aerodynamic forces? Such a differentiation might have addressed both crashes - certainly the ET one would have allowed the column control forces to even off and then allowed the crew to slow down / recover the aircraft. Maybe. Remember - More details = better answers Also: If you get a response it's polite to respond to it. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I agree that it would add in one layer of redundancy. But I know for a fact that someone will screw it up and turn both off when they shouldn't but.... It will be many times better than it is currently. But I still think they will have to give power assisted manual trim functionality to get it flying outside the USA. They should be able to do it for less than 100kg/100 nm hit to range. Personally I think they should do it anyway to create a headline of going beyond what's required before being told to for pax confidence in the type. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] They might need to shift locations of the cut out switches from next to each other alright, but clearly the manual trim function is now exposed as a key area of weakness. Mind you at the moment it looks like you need to turn the wheel what 10 time to get one degree? 20 times? A hell of a lot when it's down by your knee. Remember - More details = better answers Also: If you get a response it's polite to respond to it. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] An argument could be made that if the wheel reduced in size then changes to the linkages running back to the jackscrew could also be done to ensure that the same X force on the wheel handle causes the same Y torque at the jack screw. Then, the only difference would be more turns of the wheel to cause the same amount of stabilizer movement. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] The gearing on it currently is border line useless for large trim changes. It's something like 40 turns for a full mcas actuation of 6 degs. It's the same on he classic. One of our fo's is a pro sailor and grinds on the Volvo series size racing yachts. He can't move it way out of trim or get anywhere near the speed of the electric trim on a classic size trim wheel. And we are talking a 105kg bloke who has been known to climb a Volvo 70 mast and then slide down the back stay while drunk as a bet. And takes part in short tack harbour races grinding for fun. I can't see easa letting it fly again without the trim being sorted. And the 800 may have a AD issued on it as well. There are a few other certification issues also been noted one of which I have mentioned, there are 7-8 other issues which are not public yet and to be honest I don't really understand either. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] LittleInch - the ET pilots had full control of the stabilizer with the control wheel trim switch and chose not to use it to restore trim of the plane before shutting off the trim motors. They didn't follow the airspeed disagree memory items and did not follow the AD memory items. It is clear that any reliance on pilot competence is foolish. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] 3DDave, Yes I know that and it remains unclear why they did that without the CVR, but panic, pilot overload and multiple issues going off probably had something to do with it. However with a bit of time to figure it out, they clearly tried to correct the trim manually and couldn't so in the end turned the electric trim back on with fatal results. Having read the AD a number of times, I think they did follow the key components of it and relied on the AD saying that they could always and at any time use the manual trim. Trouble is that part of it wasn't true. If they had the ability to disconnect the trim commands from the FCC only and not an all or nothing cut out then things may, just may, have been different. The point I was trying to make was that earlier versions of the 737 appeared to allow that, either two actuators or two different cut out switches as far as I can tell. This has been mentioned before and is in a number of other posts and blogs, but below for info. 737 NG cut out switches (main and Autopilot/FCC) separate 737 MAX (primary and backup) - basically two switches in series apparently, either one cuts out the electric trim Remember - More details = better answers Also: If you get a response it's polite to respond to it. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] "It is clear that any reliance on pilot competence is foolish. " 100% correct and I have been saying this all along. It doesn't matter where they trained, what colour they are or what nationality they are. There is always the possibility of them screwing it up if you leave a hole in the design which gives them a possibility of screwing it up. Although to be honest the blog post above with the control input graphs does make alot of sense what might have gone on. We will have to wait for the report to find out what the CVR is showing. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] AH - wait until it comes out what ET management did. The ET pilots went through 3 holes of their own. Lion Air added a fourth and fifth in their maintenance management. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I am sure the ET management will be not compliant as well or the maintence. The ET pilots will have screwed up as well. BY how much we will have to wait and see until the CVR is out. I haven't heard anything about if it was a bird strike or not for a while. Lion air it will be a utter mirical if its compliant by anything even resembling normal western airline operations. Thats pilot, maint, operations, mangement and QA. I have said multiple times in these threads its nearly always the third hole which kills. Crews in general can deal with 2 holes the third kills. If you take off with a one hole already filled with say a MEL DC generator you only have two left. Some of us get it, others don't and don't change thier TEM to account for the increased threat level. But even if its heavily critical of both pilots and management, its not going to change anything about getting the MAX recertified now or how long it takes. Its going to be at least 18 months for the final report coming out. If the MAX isn't flying before that its a dead duck. Well 1330 dead ducks sitting in car parks around the USA. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Quote: All commercial aircraft have redundancy side to side via the standby instrument as minimum. When a mismatch occurs the standby instrument is consulted and then the two out of 3 win and things are reconfigured to only use the deemed good side in none FBW aircraft. But there is still no redundancy for the instruments on each side. The instruments on one side won't continue to work correctly if one of their sensors fails. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] A lot will depend on the findings of the regulators. If the regulators accept the basic design with the engines in the present location, then the question is: "How do we make MCAS safe, usable and dependable?" If the regulators rule that the tendency to pitch up at a high AoA is unacceptable then it's a whole new ball game. BTW, I understand that the flight issues were first discovered in a simulator during a climbing turn, not in straight ahead flight. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I'm pretty sure it was discovered in large model wind tunnel testing and later confirmed on test flights which is when they discovered the low speed stall issue which needed more angle to work and took out the high G sensor as part of MXAS. Remember - More details = better answers Also: If you get a response it's polite to respond to it. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Lionel and Alistair. In regards to the trim wheels and sailing winches. One solution may be a planetary gear and a safe reliable method of switching to high ratio when needed. Sure there will be problems, so, try harder. As for a solution on the Max it wasn't possible under management guidelines which seem to have been. 1. No re-certification. 2. No new training. 3. Don't spent any money. and 4. Have it ready by Thursday. Quote (Alistair) Its going to be at least 18 months for the final report coming out. If the MAX isn't flying before that its a dead duck. Well 1330 dead ducks sitting in car parks around the USA. 1330 dead ducks All those aircraft, at a discount, with the possibility of a future upgrade to Leap engines will be expensive but may still be a better return than the price of scrap aluminum. We can speculate but there are probably a few executives running the numbers and there may have been a few phone calls in regards to the availability of suitable engines. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] LittleIinch: Thank you for the clarification. Quote: I'm pretty sure it was discovered in large model wind tunnel testing and later confirmed on test flights which is when they discovered the low speed stall issue which needed more angle to work and took out the high G sensor as part of MXAS. According to my re-read of the article posted by Alistair, The original high speed problem showed up in wind tunnel tests, test flights and in the simulator. I believe that it was in flight tests 1n 2016 as you indicate that that low speed issues were detected. But it is probably better to read the article. (Linked below) Why the insistence on no simulator training? This may have been one of the reasons for the reluctance to consider simulator training: (Or 100 Million reasons) Quote (Seattle Times. Originally posted by Alistair) Early in the process of selling the MAX, according to two people familiar with the discussions, Boeing promised to give Southwest Airlines a substantial rebate for every plane if the MAX required simulator training. One former MAX worker, Rick Ludtke, said the rebate reported to him by managers was$1 million per plane, a figure another Boeing employee indicated is roughly accurate.
Link

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

BBC: Boeing suffers new 737 Max issue that could delay return

Quote (BBC)

Reuters, which first reported the new issue, said during an FAA pilot simulation in which the stall-prevention system was activated, it took longer than expected to recover the aircraft. Other sources said the problem was linked to the aircraft's computing power and whether the processor lacked enough capacity to keep up.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"But there is still no redundancy for the instruments on each side. The instruments on one side won't continue to work correctly if one of their sensors fails."

If you mean the instrumentation in the cockpit in front of the pilot there is multiple reducndancy in EFIS systems. I will give you the basic rundown, there is another level above this which the 737 is because it flys in RVSM airspace.

You have the display screens which there are 5 each pilot has there second screen which they can select if the primary fails and the info will be displayed there. If both screens fail on one side which does happen in some electrical failures then the other side is still working.
The next thing which drives the screens there is the symbol generator there are two of these which normal mode has one driving each side. Failure mode either generator can run both sides one switch to either 1 or 2 away from norm will do this. It will display dual and singular data screens
Then supplying data to the symbol generators is the AHARS and Airdata computers plus configuration data . Again two of both, AHARS deals with which way your pointing and which way is up and the airdata with the input from pitot static system., TAT. Again you can select either one to supply data to both symbol generators. So if you have a bad airspeed coming from ADC 1 (captains) you select ADC 2 and primary flight data is displayed on both sides using the data from the FO's sensors. On the Q it changes colour to show that your now in a down graded mode.

And the final redundancy is a separate instrument which is powered off the emergency battery bus and also has its own internal battery backup. Its connected directly to its own pitot static system no computers or data interpretation by anything else. And it is used as the deciding vote when the two primary systems disagree. It also has its own attitude indication.

We can get the aircraft back to base with one side with certain failures. So if we get a failure on a flight we can continue, land defer it with a cat A 6 flights limit and then fly to a maint base or home. We are grounded if the standby instrument has a fault with either airspeed or altitude.

Rvsm airspace is high up stuff where instrument sensitivity reduces due to air density. For flying in that with reduced separation there is another layer of redundancy with more computers etc. Up high the normal separation is 2000ft between aircraft in RVSM its 1000ft separation. There is a failure tree with that as well which ultimately ends up the aircraft has to descend to exit the RVSM airspace to below FL295. Instrumentation is only one part of required equipment for RVSM airspace.

The stall protection system is a separate system entirely with multiple boxes, it will have data going into the symbol generator for low speed cues etc. For my aircraft type if the AoA sensor fails on one side it will effect the low speed cue on the airspeed indicator and may trigger the stick shaker. There is a button directly infront of the pilot which flashes when the stick shaker triggers, if you hit that it turns it off. It will reset after 5 seconds of not receiving a trigger.

Now please note this is how it works with a Honeywell efis system in general terms. Each aircraft will have many more data flows. BUt the above is pretty standard for airspeed and altitude. Its certainly not the case that a pitot gets blocked on one side or one computer fails and your left with zero redundancy or only one pilot seeing correct data. There is two/three levels of redunancy across the main 5 primary screens and the third/fourth level is the standby instrument. And for info as a captain I have to land the plane at least once every three years in the sim just using the standby instrment and emergency mode instrumentation. I have only ever done it single engine. I believe if you screw it up the first time single engine they will let you do it again with both engines working as the single engine is not a requirement just you have to do one. I have always done it on the first attempt with one engine down as is the case with most Captains. To be honest its not that much harder than a "normal" single engine approach which we do at least 3 of every 6 months.

On old school analogue instruments which we call steam instruments which are the classic 6 you are correct there is no way of transferring the pipes between sides. But your talking over 40 year old aircraft now and there are not many of them flying commercial air transport in first world . And none of them can fly in RVSM airspace which means they are pretty much limited to flying in third world airspace or below FL295 which makes them uneconomic due fuel burn.

Expect a series of announcements about various systems being none compliant. Basically wait until something positive comes out and a couple of days later then next item will be released. The problem with the Stall system is linked I expect to the AP not kicking out when the stick shaker goes off while other things are happening. If its just pitch up due to incorrect autopilot settings, stick shaker will trigger and the AP comes out. If there are other things running it doesn't kick the AP out and will continue pitching into a fully developed stall with wing drop. There is no stick push system on the MAX. I am pretty sure someone else would have spotted it as well but the response to my email to one of the EASA tech pilots on the subject was "that's another one for the list" so you never know this discussion might have had a direct input into things. BTW I don't expect a reply from the tech pilots about what's going on so I am not receiving anything that's not public. And even if I did I wouldn't talk or even hint about it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Latest issue...

Apparently the electrical trim switches are not directly connected to the screw jack.

And a processor (FCC) in the mix takes the input from the thumb switches then commands the screw jack....

This processor is getting overloaded and not passing the command to the screwjack which may account for the crew not using/being able to use the electric trim in a MCAS event.

So the AP staying connected with the stick shaker running is still to surface.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Is this a result of the new software patch or did they just realize this processor was always being overloaded?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

There is a path from the switches to the stab motor that is not interrupted by any processor. The blue path informs a separate module that the trim switches are engaged, but without more detail in this not-an-electrical-schematic chart it's not clear how priority is set.

Obviously they cannot be directly connected or the trim limits and cutout switches could not function.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The AP didn't simply stay connected. It did connect and then disconnect again. I believe it gave a warning too.

What should also be questioned is why the pilot attempted to engage the AP with the stick shaker going off.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Why the pilots tried it?

More than likely nothing else was working and they knew they were going to die so were trying anything. Funny enough if they had managed to get it to stay in, it would have killed the MCAS input instead of them. Manual trim not moving plane going down, turn the electric trim back on, it doesn't work instantly either because the processor is locked up. I have never been in an about to die situation in an aircraft so really have no clue what I would do. And I really don't know how you would simulate it for training purposes either. I suspect reading an Ipad for 50 mins followed by a 2 page AD isn't going to do anything to help the situation though.

I am pretty sure they have just discovered its always been over loaded in none normal situations. Its just they haven't tested it before. As they never bothered testing with an AoA primary instrument sensor failure. I think we can be pretty certain they haven't for a secondary effect.

The real issue will be if it turns out that its overloaded in the 800 as well.

It will be some 1980's single thread processor possibly even of a 386 equivalent power. There are still thousands of antique laptops with seriel ports round maintence hangers with an abundance of operating systems that should be dead in any safety critical enviroment that are used to link to these things. And its not just Boeing. All the OEMs are guilty and windows 95 is alive and kicking in aviation.

Normally if you tried to put the AP in with the stick shaker going it wouldn't go in and you would get INHIBIT or something like that coming up in the position that the normal AP comes up which tells you that the Auto pilot is in. No aural warning charge tone.

I susppose if this processor is overloaded it may accept the signal and show it as engaged and then eventually processes it and says nope your not having that with the stick shaker and then kills it. Same with it keeping it in for a period with the stick shaker going. It just doesn't get round to processing that it should kill it. How they deal with the prioritys and errors in those modules I have zero clue. If its signal in and action and start the next item its pretty easy to see it getting swamped and not doing what it should for seconds between inputs as it completes everything else in the stack which is always full.

So it might explain the AP staying in with the stick shaker going its just processing all the other stuff before it gets to the input sticker shaker active: output AP disconnect. Then starts going with the other stuff again. Pilot activates AP and eventaully it gets round to processing Autopilot active and sends a kill signal again. By this point the activation loop in the AP has timed out with no negative don't engage signal and its back in and sends a signal. But this gets processed after the kill signal has been sent. Now everything is confused and all timed responces are being missed so nothing knows whats going on including the pilots.

To note this was on the equipment simulator at boeing they discovered this not the flight sim the pilots use for training.

I really hope they publically document all that they find wrong with the MAX and then history can't repeat itself.

I don't for one second believe this is the final issue that they will find.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The processor problem appears to be on the new software. There is no reason for Boeing or the FAA to characterize the old software performance as that is certainly never to be flown again.

The trim switch worked to produce stab trim change proportional to the duration every time it was used on all three flights.

Summarized from the Ethiopian Preliminary report:

The Ethiopian pilots never fully returned a large excursion in trim and then, after exceeding Vmo, took a couple of stabs at the switch that were too short to move the stab enough before allowing MCAS to run unopposed.

The ET302 pilots attempted to engage autopilot immediately after getting the stick shaker.

The stick shaker activated at 05:38:44 and remained on until G reversal just before impact.
At 05:38:58 the PIC (pilot in command) called to engage the autopilot and got an AP warning
At 05:39:00 the PIC called for it a second time and one second later got another AP warning.
The data doesn't show if a switch was pressed to engage the autopilot so the one second delay may be how long the copilot took to respond.
Just after this the plane responded to a manual electric trim change.
At 05:39:22 they engaged the AP
At 05:39:55, the autopilot disengaged
At 05:40:00, at the five second design interval MCAS makes the first trim down
At 05:43:11, about 32 seconds before the end of the recording, at approximately 13,400 ft, two momentary manual electric trim inputs are recorded in the ANU direction. The stabilizer moved in the ANU direction from 2.1 units to 2.3 units.
At 0.1 unit per click they needed only to click that switch 20 times to get back in trim. Instead they left trim engaged and did not oppose the final MCAS trim.

All in all, there is no evidence that the CPU had any delays in processing commands on the Ethiopian accident flight.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Where does the FDR get it's data from?

Is it the cockpit switch position.

Is it pre the processor or post or feed to the screw Jack?

Not that it really matters what they did to be honest. It's not going to change the re certification process. Or for that matter stop changes to how future aircraft are certified.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

LOL, WTF does that rant have to do about the crash? The pilots were attempting to engage the AP before the first MCAS activation and long before they put the plane into serious trouble.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

In general, it's not uncommon to include a mandatory requirement that the CPU or processor shall not be loaded more than 50%.

(Actually, this requirement is too frequently mangled to read "shall provide 50% growth", which can be (mis)interpreted in various ways.)

Anyway, if they found an explicit CPU functional performance issue during system test (which would imply at least 100% loading), then that perhaps opens up another whole can of worms.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

They will be doing system tests on old software and new software.

Until the new software gets released to the FAA I doubt Government test pilots will get to look at it. It will only be company TP's until its a finished product.

https://www.seattletimes.com/business/airline-grou...

The both accidents are still under investigation and realistically the Ethiopian or Philippines AAIB won't have the skill sets to do most of the technical hardware investigation so in full compliance of international treaties have requested the FAA as the certifying authority to help. And I suspect the FAA is more than willing to help to get to the bottom of this and try and regain some trust from the other authorities. So there will be parallel testing going of original accident configuration and the fix.

I suspect the proc was at 50% when it was fitted to the classic normal ops. It then increased significantly when they added STS on the NG. Increased again with the addition of MCAS normal operations. Stick in a failed AOA and none normal ops and its utterly overloaded. I don't have a clue how good the thermal dissipation properties of said box are, it could very easily be throttling back due over temping as well.

"(Actually, this requirement is too frequently mangled to read "shall provide 50% growth", which can be (mis)interpreted in various ways.)"

It was at 50% when first certified in 1990's then the growth has been STS being added and then MCAS. So grandfather rights claimed so as not to have to get a new proc and it certified.... And when they go and check it in the 800 they find its running at 70% normal ops with just STS running extra.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

A question:
In the event that Boeing had developed a higher, extendable, landing gear, would that have triggered a need for simulator training?

A correction. I mistakenly understood that Southwest Airlines had ordered 100 Max aircraft.
On checking I see that Southwest Airlines have 200 Max aircraft on order.
If new landing gear required simulator training, it would cost $200,000,000 in rebates to Southwest alone. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Don't forget 80k x 200 because they paid for the AoA indicator which is now fitted as standard. Anyway some more info on the latest processor overload situation. Apparently it can get overloaded with out MCAS triggering. And the plan is to spread the load over more "boxes" which I suspect will open a barrel of worms never mind a can of them. https://theaircurrent.com/aviation-safety/faa-and-... "In the event that Boeing had developed a higher, extendable, landing gear, would that have triggered a need for simulator training?" Depends if the procedures had changed or there was anything special about it. But I would be suprised on its own that it would. If there was a different setup for the hydralics to run it which meant different QRH procedures then yes. I think you can be pretty certain that the FAA will say that ground school and sim training will be required. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] waross, I can see you like that solution, but the magnitude is large. From what I can gather the 737 would need to be higher in the order of 600 to 700mm. That's an awful lot of extension. Picture is the difference for A320 to 737 Remember - More details = better answers Also: If you get a response it's polite to respond to it. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] There's a key sentence - "The deliberately broken microprocessor had become overwhelmed ..." It appears the FAA is going to chase every single-point failure consequence and probably look to make sure pilots can ignore all the warnings. It's a good thing for really lousy reasons. You know that ET pilots got neither ground school or sim training about the AD, right? So why would they need more training? RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I read that "deliberately broken" to mean they intentionally fed a lot of inputs into it to see if it could keep up with the commands; not that the processor was physically broken or impaired? "test pilots flew a scenario causing a fault in a microprocessor..." That sounds like too many commands, not intentional hardware failure to see the effects RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] No, they inserted a fault; two paragraphs above that sentence, it says "...intentionally broke part of the 737 Max's flight control computer." That's actually pretty sound regression testing. The "had become overwhelmed" is the truly scary part, since it's more likely that the processor fault tolerance mechanism had failed to do its job. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Too bad they don't really clarify. How can "too many commands" be fed into it? It should only happen if they create a defect somewhere else as the normal process is polling the various inputs preventing "too many commands" from ever happening. The FCC should be a state machine and not able to ever see too many commands; the worst is if there is a state input that changes faster than the system can respond, like if someone applied milli-second duration switch inputs such that the the average status was ambiguous for long periods of time. Rumor reporting is really not helping and the FAA should be 100% transparent about all the tests they are doing. I think I'll just discount other sources as entirely unreliable and set pitch and power. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] "You know that ET pilots got neither ground school or sim training about the AD, right? So why would they need more training? " They definately won't need any more training because they are dead. License revoked. European MAX drivers just got the AD emailed to them by their flight safety officer. And they had done the same ipad training. Once the aircrat is eventually released for service again if the FAA sticks with the rest of the worlds CAA's there will be differences training encompassing more than just a ipad course. It will involve sim work. Now Sully has spoken his mind they will have to do it anyway even if it just one session for the American market, even if the FAA doesn't think its required. EASA is pretty much certain to require it what ever happens. Another article with gives a few more difference between the max and NG https://www.pilotweb.aero/features/737-max-scandal... just read all the way through its not 100% arcuate or fair to be honest. But there is some good stuff about the addition flight control features that are going on which haven't been mentioned yet in the threads. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] The article is unclear, and that's intentional on someone's part. The relevant symptom, and the only other "fact" is Quote (https://theaircurrent.com/aviation-safety/faa-and-...) The test pilot initiated the runaway stabilizer trim checklist, according to the people, but found the electric trim switches on the pilot's yoke unresponsive as the stabilizer continued to force the jet's nose down even further. All the other words in the surrounding paragraphs are suppositions and speculations; until Boeing and FAA go through the datalogs in detail, we only have two facts, a fault was inserted to induce the stabilizer to pitch the plane down, and the switches to stop that were unresponsive. There are dozens of possibilities. Note that this was likely a new fault insertion, since they likely choose one that was different that any they might have tested in the past. Fault insertion testing is a extremely slow process and it's likely no more than a few dozen faults were ever tested in the past by the FAA. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] In some fault insertion campaigns, the customer may require testing some number of additional faults for every fault not properly handled. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] "...someone applied milli-second duration switch inputs..." If that was an actual issue, then the system designer needs to back to school to learn about debouncing inputs. It's standard and essential design practice to debounce switch inputs, because switch contacts do bounce, irrespective of how someone pushes it. In other words, that's probably not a good example towards your point. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I thought it was pretty clear from the article that they performed a fault insertion test, something that would result in the flight computer forcing the nose down; the expectation was that the test pilot would be able to disable the effect of the fault and recover the plane. It's certainly possible that the inserted fault had an unintended consequence, or that the simulator no longer matches the configuration on which a similar fault was previously tested and averted. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Could the fault have been a failed relay? Either wire chaff or welding causing on or off either continuously or "sparking". A conflicting trigger of flaps down would put a spanner in the works and force the nose down. The failing of relays seems to be a common fault on the three aircraft types I have flown. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Thing is those cut out switches don't actually kill the power to the jackscrew only the Stab trim cont CB can do that. The variations on faults is collosal. You have to either make the trim stab to be able to be manually used over the full flight envelope plus over speed buffer or you have to go through everything that can control the thing and make them fail safe. If you want the pilot to be the backup system. BTW I can't see it flying again by January in the USA. And I am 50/50 if it will be flying outside the USA for next summer season. I susepct it would be quicker and easier to just sort the manual trim system out so the pilots can use it without having to meet responce times. Then they don't have to fault test every input to the screwjack. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Boeing's 737 Max Software Outsourced to$9-an-Hour Engineers
https://www.bloomberg.com/news/articles/2019-06-28...

Seems like another example of putting profit over people. I know a lot of firms outsource these types of jobs but I didn't know Boeing would too.

Laron B.
Results. Not Recommendations
BurrowX
Sr. Chemical Engineer

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Computer overload, a real world example.
When the 8080 chip arrived on the scene there was an attempt to use it to control a lumber sorter.
As each board arrived at the sorter and was placed on the J hooks it was measured and the information fed to the computer.
The J hooks carried the boards over the sort bins and as each board passed over the correct bin, it would be slid off the J hooks and drop into the bin. When a bin had enough boards to make a standard package, boards of that size would be diverted to the next empty bin.
The momentary inputs would be buffered and acted upon in turn.
The boards would be arriving at a rate of possibly three a second.
With only 8 data bits available, there was a lot of thrashing to memory to handle the information and to make comparisons.
The computer at times could not keep up with the lumber flow and would start missing boards.
Computer control of lumber sorters had to wait until faster chips with more than 8 data bits were available.
One example of the type of thing that may overload a processor.

In an aircraft, processing an input and providing an appropriate output will be rapid.
Then add in error checking, comparisons with other inputs (redundant AoA indicators), a validity check based on rate of change of the signal etc. and the processing time will be multiplied many times over, possible by an order of magnitude or more. (base 10)

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Thank you for your patience and kind reply, Alistair.
It would be nice to be able to talk to the author of the article as to what exactly he meant and just how severe the problem is.

Quote:

it was necessary to push forward on the yoke to prevent the turn tightening and the G-force increasing, after which the aeroplane would then pitch up into the stall unless the pilots input a lot of forward control column movement.
I have the impression that Boeing tried to fix this problem with no success and then went to plan B.
If you can't fix it, try to cover it up.
As I understand it, at high AoA the engines act as a control surface and add to the action of the stabilizers.
Once those engines start to catch enough air to make a difference, the worse it gets, the worse it gets.

Quote (Alistair)

If you go into negative stability it's impossible to stay in control. You will survive maybe 5-10seconds before it gets away from you.

I'm not trying to put you on the spot by quoting you.
I'm respectfully asking for your comments.
Another point for comment.
We have talked quite a lot about instrument disagreement.
How about "Seat of the pants" disagreement?
When the plane enters the unstable flight mode, I understand that the G forces on the seat of your pants tell you to back off, while the reducing pressure from the stick may be telling you that you can increase the AoA.
What is that like in the pilots seat?
A hypothetical failure mode.
A late flight, end of the last flight before days off.
For whatever reason MCAS has been disabled.
There may be instrument disagreements that are related to the failure of MCAS.
Bad weather and the pilots make a go around.
They make a climbing turn and get into the unstable condition.
And another one bites the dust.
The focus has been entirely on what happens when MCAS over reacts.
MCAS not acting at all is another serious failure mode.
Thank you again for your patience.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

As an instrument pilot you veryquickly learn that your bum gives no details to your actual flight profile.

It's a huge section of human performance about the limitations of the human sensory system and what we do with it in aircraft. Basically you can only trust the instruments. Google the leans and that should get you started.

As for the stability stuff Google spiral dive. Stability is to do with returning to a fixed profile. The ossillations have to decrease after an input is injected. They test it by belting the control colum with a hammer. So if you belt the front face and the nose dips then raises again trading kenetic for potential and repeat and the amplitude deceasss with time thats positive stability. If the amplitude increases that negative stability.

If your aircraft is stable given enough hieght it will always return to the same trim speed. If it's unstable it will never do.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

With your eyes shut I can have you drinking a glass of water upside down thinking your in a gentle turn.

I can also have you straight and level with absolutely nothing required but you are sure we are heading to the moon turning to one side. And need immediate forward stick and roll not to die.

It's all to do with the fluid in your inner ear and it's momentum. Once you don't have a horizon to look at you have no clue, g is subject to the attitude of the aircrsft. Just because it's positive doesn't mean the ground is below your bum.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

2
After a couple of days research including technicians that are licensed to work on the max.

It appears that the FDR does not record pilot input to trim via the thumb switches.

It only records input to screw jack controller.

So if the pilots are using the thumb switches and something in-between the thumb switch and screw jack controller does not action said pilot input there is no way of knowing if the pilot had there thumb on the switches for the whole time or never.

Which further adds to the mess because this completely contravenes the Annex 6 requirements.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

^ That really calls into question a lot of that questionable manual trim input, like stopping at level and not continuing to nose up, doesn't it?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"...FDR does not record pilot input to trim via the thumb switches."

The Preliminary Report for ET302, in Appendix 1 'ET302 Preliminary FDR Data' (page 26 of 33) shows a purple trace marked "Trim Up-Man" and "Trim Down-Man".

The near rectangular shape of the waveform and surrounding context seems to imply it's the thumb switches.

But perhaps I'm misinterpreting it; so clarification always welcome.

Extract:

Edit to add: Perhaps the Manual Trim data is derived from the other data. i.e. Jack Screw actuated and not Automatically, so it must be a Manual command. Pure Speculation Alert on this.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Other side of the same chart confirms it's:
"Manual (Electric) Trim Command".

Extract:

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Is it possible the manual (electric) trim command lines we see are just the processed outputs?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Yes, that's possible. My edit above offered such a scenario.

"Perhaps the Manual Trim data is derived from the other data. i.e. Jack Screw actuated and not Automatically, so it must be a Manual command. Pure Speculation Alert on this."

If the system designers were running out of FDR input pins, they might quite reasonably decide to prioritize the Jack Screw over the Thumb Switches.

Obviously actual facts will take precedence over such speculation.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

There is no indication what the thumb switch positions are in. Only that the screw jack has recieved a manual (electric) trim input.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

According to https://www.reuters.com/article/us-ethiopia-airlin... the FDR records 1790 parameters, although most of what I've seen says that it's at least 91 parameters, required by the FAA.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Its not the FAA is ICAO annex 6 which dictates what's the minimum items recorded.

The document itself is extremely dry.

https://www.bea.aero/uploads/tx_scalaetudessecurit...

That seems to be a reasonable summary of the whole thing from a french study on the subject.

These days they are downloaded every 2-3 days through the QDR and then the data in theroy used to check the pilots performance. Although it is very variable what individual companys do with that information once they have it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"...are downloaded every 2-3 days through the QDR..."

AKA: Quick Access Recorder (QAR).

There was one accident where it was reported that the investigators were initially misled by the QAR data.

The QAR data was cut-off about a minute before the impact, so the investigators surmised some sort of electrical power failure that was thus perhaps a contributing factor to the crash

Later they figured out that the QAR, unlike an FDR, will buffer data before writing it to the non-volatile storage. This is done to manage the flash memory hardware (blocks, write cycles, lifespan). After all, there are no maximum latency requirements on the design, as supporting crash investigations is not its purpose.

So the final minute of data was lost in the buffer, and thus not recorded on the QAR's non-volatile memory. Thus causing temporary confusion.

They'd be well aware of this going forward.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The qdr is only for qa purposes of flight standards it will have nothing to do with the max investigation.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"...only..."

In general, if a QAR memory unit survives and is found, then it certainly would be included in any air accident investigation. Just like any other available evidence. No reason not to do so.

Specifically for the Max:

I presume that any QAR module would have been destroyed in the ET302 crash.

But the Lion Air Preliminary Report (ref. KNKT.18.10.35.04) states, "The investigation has received the QAR data for flight for analysis" and "The KNKT has received the Quick Access Recorder (QAR) data for the accident aircraft since its delivery to Lion Air for analysis."

It's not clear if they're referring to QAR data for the incident flight, or previous flights, or both.

In any case, QAR data (if available) is certainly in scope.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

It's only sampled every three seconds FDR is normally every second or more.

And the channels are not calibrated.

Yes if they find the data card which normally lives in a cockpit rack somewhere they will have a look at it the same as any phones they can find and the egpws memory and GPS logs. They will use anything and everything they can get their hands on. The advantage of qdr is it's relatively easy to read and load up in the company qa software. FDR has to be processed and not many places can do it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

What I suspect they are using it for is to see if there were any other mcas triggers which occured but the crew didn't report

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The United Kingdom are suggesting maybe all pilots need some training.

http://publicapps.caa.co.uk/docs/33/SafetyNotice20...

Note that the graphs are misleading as it is unlikely a digital FDR can record a spike; it's sampling and the samples should be graphed as individual data points. For very short durations, one cannot extrapolate the integral of the area of a spike to determine the expected output.

Looks like data is fed to the FDR via a DFDAU www.redimec.com.ar/contenido/productos/pdf/1425474...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Its a EU wide push in this area via EASA. The CAA is just the messenger to the UK AOC holders.

There have been several new topics come up over the last few years.

Flight upset and unusual atitudes came in 3 years ago with class room content and sim exercises. They monitor the global accidents and incidents and if they see a trend forming they start including the situation in the syllabus.

There is a move to reduce the separation in the terminal enviroment to basically try and fit more aircraft in the same airspace. The closer you get them together the more likely they are to encounter wake vortex.

They don't actually have a very predictable model of wake vortex how it moves or how it disapates. There are a few rules of thumb but basically you can't predict when your going to encounter it. It does kill, a calibrator recently in Dubai encountered it and went in 4 dead. Pilot was self seperating and screwed it up and paid the price.

So the system does react to changes in the operating enviroment and new risks that appear. No pilot will argue that training couldn't be improved. But your up against accountants, training is very expensive and disruptive to the airline cash flow. I know my Chief pilot would love to have 3 days of sim every 6 months currently he has 2 days which is 1 day more than legally required 3 days every 12 months. But there is no way he could sell that to the financial director. Currently there is that many hot topics that with the mandatory stuff of engine failures etc they are running out of time in the 3 sessions.

Pax will always take the cheapest seat, if your airline goes above the min required then its at a commercial disadvantage to the competitor that only does the bare minimum as dictated by the system.

Or are you expecting me and other pilots to stump up 2000 euro an hour to pay for additional sim training?

On the runway excursion topic there have been 7 go off road in the last 7 days.....

http://avherald.com/h?article=4c9d4a5a&opt=0

As I said if your going to go off road the 737 is the aircraft to do it in. How the hell that nose gear stayed on going through a drainage ditch I have no idea.

Hey I have an idea why not have every certifiying engineer have an exam every 6 months which will last 4 hours. Multi disapline including law will get fired at them every 15-30mins mins, they have 3 seconds to make a snap desision on which path they have to go down and then they have to play it out to the end. If its the wrong desision they fail and have to undergo retraining and loss of salary. The exam will done starting 4 hours into current sleep period. It won't be done at the place of work they will have to travel 4-5 hours the day before and then have 10 hours in a hotel, then 12 hours later do a second exam same setup. The previous 6 days they need to do 8-12 hour shifts and have at least 3 changes of start time.

On top of that every person involved with design and aircraft production will have to do 3 days of ground school, human performance, current legislation, best practise, and a day of case studys detailing screw ups and also the environment they are actually expecting people to operate the equipment in.

I suspect training/checking the Engineers and giving training to production first line crew will give more return than increasing pilot training.

I believe currently there is the sum total of zero training required or given at OEM level.

Our mainteners and operations staff have to go through 2 days a year of the CRM and case studys stuff. And it does make a difference.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

And if anyone wants to see what the pilots get here is an example

I choose it because the subject is relevant to this topic.

https://youtu.be/WfNBmZy1Yuc

Unfortunately this video is now banned for training because it teaches the American way of dealing with flight upset using rudder to deal with roll. Apart from that its pretty good I think.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"Pax will always take the cheapest seat..."

For long overseas flights, like wine in a restaurant, the 2nd cheapest offering is often a better choice.

Excuse the topic drift.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I know that and you know that. But that's not the routes these planes will be flying. And not with the type of pax that appreciate the difference between any wine apart from the alcohol content.

If you ever get to speak to a revenue management team member and they open up on how they play the game its eye opening. Especially on contested routes.

Even a 5 euro/ 5$price difference in seats can create 10k worth of losses or of profit on a route in days. Which is why having leap equipped hardware is so important. If you can save 14% of the fuel burn you have a huge margin to play with against none geared fans operators. You just need to drop your price to 5 below the others operating the route and you will still be in the green due fuel efficiency. They have higher running costs anyway and loosing the low yield traffic means their costs are not covered. Very quickly they have to pull out of the route. This then allows the other company to increase prices back above what they were before and generate even more revenue. The longer the max is grounded with the neo getting pumped out at 55 a month the more likely that Boeing operators will just go bust. Just now they will have planned on MAX fuel burns with the ticket pricing so running it with other hardware will just add insult to injury. Hence early bird flight cancelations even if they have other hardware to operate the route. Everything with high volume economy pax is about seat price. If a neo operator can charge 180$ and a 737-800 operator has to charge 200$the neo will be full and vastly profitable and the 737-800 will be struggling to break even more likely loosing money. Ancillary revenue will come into it but thats when it gets really crazy when you start talking about that side of things with a revenue managment type. Thats another thing that alot of pax don't look at. They just take the basic ticket price as there main decider and they are completely oblivious that once you add in all the extras that are included in the other carriers price its actually more expensive. Which is why most airlines now are dumping full service tickets. The pax want to pay for stuff individually and you will be hit hard if you don't allow it. So now its pretty much standard. BUt they never get the reason why a A-B-C ticketed route is more than a A-B and B-C ticketed route. So they always go for the A-B, B-C then they are all over social media when they get dumped in some airport after missing thier connection because they have to recover baggage and deposit it again. They expect the airline is going to put them in a hotel and get the next avialble flight sorted to the destination. Well its the same airline as was selling the A-B-C ticket isn't it and they were late I missed the 30 min connection and they didn't hold the plane..... So they have to look after me.... well they would if you had paid a bit more for a A-B-C ticket but you thought you were being smart getting a cheaper ticket doing the same route. More than likely they had done the route multiple times before with no issues. Then they get caught once and it burns all the savings they have obtained from doing it 10 times previously. BUt if its 10 euro/$ cheaper to split the ticketing they will do it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

(OP)
Woah,
RE: video posted earlier. Rudder hard-over and "cross-over angle of attack" in the training video - the instructor makes this disturbing statement:

Quote (Captain Warren VanderBurgh)

"in the 757/767... if you are at flaps setting 5 and plus 40 on speed, you'd be there; you are at cross-over angle of attack. At that angle of attack or any higher your rudder is a more powerful roll control than your ailerons and spoilers. What I'm saying is that if the rudder is fully displaced by you or a malfunction, fully displaced roll controls in the opposite direction will not stop the roll [emphasis mine]

That's quite disturbing.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

You deal with it by reducing power on one of the engines or increasing the other one. But you have a huge airbrake effect as well. But its not easy and you have an extremely small window to stay in controlled flight.

The dynamics of yaw and its effects are another area of pilot knowledge which is quite lacking.

When you get a yaw induced rollover you have very little time to reconfigure the power to retain controlled flight.

Here is a video of someone letting the speed go below Vmca on one fully functional engine. He had both engines running when he should have feathered the malfunctioning engine. An unfeathered prop at low power produces more drag than shutting it down and feathering it. So by keeping the engine going you actually raise the Vmca by a significant amount. Speed gets down to below Vmca and the rudder runs out of authority to balance the power on one side and the drag on the other and over you go. Pilots want to keep an engine running even if its producing minimal power. When realistically if it is producing anything less than about 10% torque its doing more harm than good. Now this only applies to prop aircraft. Jets don't produce as much adverse yaw at min power settings so keeping one of them ticking over may be advantageous to keep electric and hydraulic services.

https://youtu.be/YqmomTUVsAw

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"Woah,
RE: video posted earlier. Rudder hard-over and "cross-over angle of attack" in the training video - the instructor makes this disturbing statement:
Quote (Captain Warren VanderBurgh)
"in the 757/767... if you are at flaps setting 5 and plus 40 on speed, you'd be there; you are at cross-over angle of attack. At that angle of attack or any higher your rudder is a more powerful roll control than your ailerons and spoilers. What I'm saying is that if the rudder is fully displaced by you or a malfunction, fully displaced roll controls in the opposite direction will not stop the roll [emphasis mine]

That's quite disturbing."

That's another chapter of the 737 story, there were two 737's lost to a rudder control issue.[edit: several more suspected] They rolled in when the rudder jammed hard over.
https://en.wikipedia.org/wiki/Boeing_737_rudder_is...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Bloomberg: Boeing 737 Max's Autopilot Has Problem, European Regulators Find

Quote (Bloomberg)

...EASA’s checklist includes a number of issues that have been disclosed: the potential difficulty pilots have in turning the jet’s manual trim wheel, the unreliability of the Max’s angle of attack sensors, inadequate training procedures, and a software issue flagged just last week by the FAA pertaining to a lagging microprocessor. But the agency also listed a previously unreported concern: the autopilot failing to disengage in certain emergencies. ...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The power of discussion groups like this...…

As I said I am sure someone else would have spotted it but when I sent the email to one of the EASA tech pilots it seemed they hadn't spotted it yet.

I really can't see how Boeing can get it flying again without redesigning the trim system.

There is another aviation news site which is behind a pay wall that's reporting there is a list with over 200 items on it that need fixing with the FAA. But the manual trim issue is not on it.

I really can't see how it will be allowed to fly in Europe again without them fixing the trim system. And if EASA require it the rest of the other Global authorities will want it fixed as well.

I can't see it flying next summer season now to be honest. September is just an executives dream world. And the more testing they do the more problems they will find.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Oh, the luxury of being a NON aircraft software engineer. Mazdas would be falling from the sky...
https://abcnews.go.com/Business/wireStory/mazda-re...

Brad Waybright

It's all okay as long as it's okay.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

On the topic of simulators, training, and proficiency checking, some might find this interesting, from a historical perspective.
Link

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Quote (thebard3)

Oh, the luxury of being a NON aircraft software engineer. Mazdas would be falling from the sky...
Never mind that, it's already completely obvious that we have game programmers on the loose with no clue about physics, hard real time or other serious engineering disciplines such as in the loop validation, writing mission critical code for Tesla, Uber et al wannabe autonomous vehicles, with predictably disastrous results. Not faulting the programmers directly, but the organizations they work for that think they've got the bull by the horns, when the opposite is the case.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I know a top gaming programmer.
He works for a top game producing company.
When I saw him last year he was supervising about 300 programmers.
I think that the pay may be better than at Tesla.
He did work for awhile for a company owned by Mr. Musk. (Not Tesla. Another property.)
He's gone back to gaming.
Talking to him about his past projects, I suspect that he does have a clue.
I guess if a game programmer can't get a good job with a game company there is always Tesla.
But I accept your point of view as it applies to Tesla programmers but not all game programmers.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Quote (waross)

Talking to him about his past projects, I suspect that he does have a clue.
I don't think anybody was suggesting that there are not excellent programmers and intelligent people in these industries. But you have to realise the required standard of quality control is COMPLETELY different.

It is often commented that modern software be it games, productivity software or operating systems has vastly more bugs than older software. Part of that is complexity. But also with online hotfixes and bugfixes the pressure to get it perfect on the first release isn't as great.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

(OP)

Quote (hemi)

On the topic of simulators,

There's a lot that's out of date in that 45-year old article. Have you been inside a modern full-motion, wraparound-vision flight simulator? It's pretty intense.
I worked at CAE Electronics for a summer internship. In the 90's it was already getting pretty good. It doesn't have to convince you it's real to give you the visual cues to your orientation (or disorientation, depending).

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I guess the FCS systems guys failed to do their requirements work and AoA evaluations correctly. Would they blame materials guys for not making aluminum as stiff as boron? Obviously a flaw with those terrible engineers.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I think the initial remit was correct because it had the G limitation included as a dual trigger which is why it got past the test pilot sign off.

It was after they started playing with it to sort out other issues that the consequences of the changes to the failure modes was not caught.

The flaw is in the system/management not per say the individuals or teams doing the projects.

On a seperate note that article is way out of date. The Q400 the first time I landed it I had 70 pax down the back. This zero flight time rating is not an option for low experenced pilots or for that matter training through a normal training provider, You have to have 3000 plus hours in transport twin engined aircraft. It has to be through a company you are going to fly for. And the first 4 sectors need to be with a special training Captain/examiner. The sim used needs to be a level D sim. If you can't meet the requirements you need to do 4 or 6 takeoffs and landings in the real aircraft.

Its not a problem I found until several months down the line when I had a positioning sector empty landing with 700kg of fuel on board which gives a 19 ton landing weight. I was more used to landing with 26-28 tons. The Q400 is utterly horrible landing at sub 21 tons. I liken it to trying to land a shopping trolley getting taken off a curb empty trying to get the back wheels down first. It came as a bit of a shock to be honest. If i had done the circuits in the aircraft it would have been about the same weight. That said when you do your first sectors with pax in the back you have never flown the machine at max TO weight or landed at max landing weight. Loading it up with ballast half way through the circuits is not a realistic option.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Quote (3DDave)

I guess the FCS systems guys failed to do their requirements work and AoA evaluations correctly. Would they blame materials guys for not making aluminum as stiff as boron? Obviously a flaw with those terrible engineers.

Quote (Alistair Heaton)

It was after they started playing with it to sort out other issues that the consequences of the changes to the failure modes was not caught.

It is looking like these problems exist because top level Boeing executives made a smokey room deal with top level airline executives to deliver equipment with certain imagined specifications at a certain date/cost. They then used every corporate trick in the book to push it past engineering objections, engineering realities, test pilot sign-offs, and FAA approvals. The problems themselves are trivial and would have been easily caught and flagged by Boeing engineers and even Boeing's design guidelines.

This is a bit afield but it reminds me of how Vale was manipulating geotechs in the Brazil tailings dam failures or the way owners were gaming the system in the Elliot Lake Mall collapse. Engineers and conscientious individuals simply don't have the power to over-ride this type of corporate behavior. And by 'corporate' I don't really mean corporations per se but the corporate behavior of humans.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I agree charliealphabravo.

Quote (cab)

It is looking like these problems exist because top level Boeing executives made a smokey room deal with top level airline executives to deliver equipment with certain imagined specifications at a certain date/cost. They then used every corporate trick in the book to push it past engineering objections, engineering realities, test pilot sign-offs, and FAA approvals. The problems themselves are trivial and would have been easily caught and flagged by Boeing engineers and even Boeing's design guidelines.
This is not an engineering failure.
This is a management failure.
Management telling engineering when they should be asking engineering.
There may be similarities here to the attempts to have the value of pi changed to 3 exactly by legislation.

It appears that management also carefully chose the design team to exclude any engineer with the knowledge and intestinal fortitude to slow the schedule by saying;
"No. This is not wise. This is not right."
One such engineer did slip through the net and did stand up to management on a point of safety and won his point.
He was quickly removed from the project.

Managements mind was made up and they would not allow anything to compromise an unrealistic schedule.
As part of the deal with airlines don't forget the $200,000,000 plus penalty if simulator training was needed. When management, from the great height of ego and authority and through a smoky veil of hubris, issue orders contrary to good engineering practice, bad things often happen. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] I wonder what the cost of initially certifying the Max as a new plane, while fully addressing design issues and updating its technology, compared to the costs associated with the grounding, investigation/repair(s), lawsuits, loss of consumer confidence, and loss of orders would look like. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] It's not necessarily ego and hubris, since the execs in question are beholden to the board, and the board is driven by stock valuation. The bottom line, literally and figuratively, is that if any executive attempts to do the right thing and wind up spending profit, he's gone at the next board meeting. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] Well it was 32 billion$ reportely for the 787 program.

According to JP Morgan the max grounding is costing currently 1 billion $a month to boeing alone not including airline costs and penalty charges. I think there was a time limitaion on that as well that a new gear kicked in after a certain period and the 1 billion$ increased. By how much I don't know. In April Airlines had racked up 2 $billion in costs in two months. Its something like 150 000$ per day per airframe. Not including maintenance and parking etc and replacement aircraft.

So a guess is 2 billion total per month Boeing and airlines. Alought the airline cost will start ramping up quiet rapidly after oct as NG's were due to be returned before D check. So 2 billion a month currently After Oct 3 billion after feb next year possibly 4 billion a month.

And that won't include any mods that have to be rolled out to get them flying again or cost of getting them certified by EASA and the like.

A new plane would have taken 10 years to design and produce. By which point Boeing would only have a fraction of market share that it had before the NEO came out. I suspect time was the biggest pressure.

As a guess I reckon it must have cost over 10 billion \$ so far for all concerned without the legal stuff and consumer confidence accounted for. By January it will be over 25 billion. Next April which is not unrealistic outside the USA should get it up to the cost of developing the 787.

Even when they get them flying again there will be a huge warranty part replacement hit. Expect daily gear issues and flap failures as seals go after sitting unused for months. It will take at least 6 months before those type of failures have worked thier way through. And the aircraft will invent new failure modes because its just not normal to have them sit for a month on the ground never mind a year. And your going to have well over 1000 of them in the air all in the same state of over 1 month mothballed at the same time. And a pilot is bound to screw up and crash one. And there will be a few that the pilot doesn't screw it up and they crash anyway because the gear won't go down and lock. And more than a few steering manifolds go taking the plane off runway. Every hour of the day somewhere in the world the pilots will have the QRH out. Which could have been a paperless setup with automatic ticking of items aka 787 and 777 but due grandfather issues it s a crap book which lives behind the captains seat which takes 100 times as long to find the right page to run never mind execute.

I suspect each airframe once everything is sorted will end up costing more than a 787. A max 8 is 117 million un-discounted. A 787-8 is 240 million. A 747-8 is 405 million. Its normal to get 10-40% discount on the list price depending on who you are and how many your buying. BTW that doesn;t include the powerplant cost. Which is mostly power by the hour.

I really have no idea how much the final bill will be....

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Quote (Alistair Heatoin)

A new plane would have taken 10 years to design and produce. By which point Boeing would only have a fraction of market share that it had before the NEO came out. I suspect time was the biggest pressure.
Agreed, but they had every opportunity to get the Max right if they would have let the engineers do their jobs and spend a *little* more money than originally budgeted.
Alternatively they could have taken a middle road and reactivate the 757. Of course that wouldn't meet the fleet commonality goal, but then neither would a new plane.

Quote (Alistair Heaton)

I really have no idea how much the final bill will be....
Indeed. Orders of magnitude more than management bargained for when launching the project, evidently. Heads rolling at the end of all this, anyone?

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

https://samchui.com/2019/07/10/easa-identifies-737...

I have been told that "the" email was the instigator to this issue.

And although we do have our differences in opinion on pilot presume responses to the situation that occurred, in the cockpit in both accidents. In actual fact it was 3DDave who actually highlighted this issue with his comments on the FDR readouts which led me to see the issue and then pass it onto the tech EASA pilots which then took it further. Without his/her input an absolutely colossal swiss cheese hole could have been missed. BTW the tech pilot I passed it onto used to be a BAe structural engineer on the BAe 146, J41 and also work on Typhoon. I met him flying the BAe bus routes out of Warton when he was a PPL. He is a CEng and knows his poo both flying and building/fixing the things. He has a Phd in some materials bollocks none related to aviation.

I realise that it might cause some mixed feeling on the subject but in my world we are as open as we can be on our own performance and also information flow. Holding onto that info doesn't sit well with me. I want to congratulate 3DDave for adding to aviation safety but I realise that it might not sit well with them... Anyway as a pilot I thankyou for highlighting a real safety issue but can understand why that causes mixed feelings.

I really don't think money was the main concern it was time. Which had a knock on effect of market share.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Then again, time=money. Of course, some tasks are not amenable to getting compressed in time, such as gestation. Nevertheless, Boeing is effectively going to be way later to market than they anticipated, never mind all the money, and forfeit of their good reputation, with all stakeholders: passengers, customers, regulators, investors,... not to mention industry partners.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Umm, good. As long as the major issue of industry acceptance of poor pilot training to save a few bucks putting pilots in seats is dealt with also. I also hope it leads to a complete and thorough investigation of all aircraft control systems.

By-the-by - what information was gleaned from the FDR? It's an interesting claim and it would be good to see what the basis for it is.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I don't see how it's something to be real proud of. You got it completely wrong writing an email about the autopilot not disconnecting when the stick shaker went off.

The accident report says it was connected while the stick shaker was going off and that it did disconnect itself.

That news report says it doesn't completely disconnect. There was nothing in the report about the autopilot remaining partially connected. I'm really curious what partially disconnecting even means. I always thought the autopilot was either on or off and didn't partially work.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Its meant to be impossible to have any auto pilot function in while the stall protection system is active. Ie the AP kicks out as the stick shaker triggers. in fact there is a long list of things that if they annoy it,it kicks out. The FBW machines are different and they come under a different set of rules and have funny modes which are type specific. Some would say the only way the AP is truely out on FBW is when you in the very bottom emergency control mode.

There can't be a pause or some functions working and others not the whole lot has to come out on none FBW.

The stick shaker indicates incipient stall situation so the plane isn't actually stalled and no pilot input is required to recover if the there is nothing increasing the angle of attack. Due to the certified stability of the aircraft the nose will hold position or drop decreasing the angle of attack. You don't need power to recover from a incipient stall. You only need to maintain or decrease the angle of attack. In real life the nose drops anyway as it disconnects. The only time this falls over is if the trim has run away and is way back driving the nose up. But that's a none normal mode.

The FDR records every 2 seconds. For it to have multiple points with the stick shaker going and AP in means that its not a freak pickup of both being in at the same time due to signal lag.

I forget the chart it was a comment on it was 2 threads back I suspect.

Anyway the email was only the instigator it will have been checked with the relevant raw FDR data and CVR recordings which aren't public. If the stickshaker is heard before the autopilot disconnect alarm then its a fail for certification on the CVR and they will be able to see it on the FDR. It would have taken under 5 mins to check if it was a valid concern. And its turned out to be a major valid issue.

Your not wrong it should be either in or out, and impossible to put in if a long list of requirements are not met. There are 3 modes starting with pitch hold and wings level through to high end function when the FMC is running the show. The FMC has protections in it. The other two levels don't.

They won't be able to tell if it was partially in from the FDR. They will have done system tests and looked at the relevant raw data signals to see what is going on. FDR recorded AP in and Stickshaker on. After the tests it appears it was stickshaker on and AP sort of on.

The risk is that the plane is climbing in the second level mode of vertical speed and as it gets higher altitude the engine power drops with density decrease, density change also requires the angle of attack to be increased to maintain rate of climb. Now this is where there used to be conflicting opinions across the pond. The European regulators required a secondary system of a stick push to force the nose down if you went any further than incipient stall. The FAA never had this requirement and was very against stick pushers and made people remove them before operating on the US register. With FAR 25/JAR 25 this was then dropped but no requirement to have one fitted. Conversely the Europeans dropped the requirement to have one. The ins and outs of the arguments for and against is colossal and centres round relative perceived risks of system failure V it actually helping save a plane. But basically it adds weight to the aircraft which the OEM's don't like because it decreases the traffic load and range. FBW doesn't have one because its meant to have performance fences as protection. And legacy product lines such as Q400 have them because the plane was certified with them with the 100 series and to keep grandfather certification they just kept it.

To add there are certain tail configurations that do require a stick push world wide. High T tails when the pitch control surfaces can be blanked by vortex coming off the wings in a stall do require them. You can get into a thing called superstall when you can't recover even with full power on.

As for pilot training they are all issuing guidance and have been for years.

https://www.faa.gov/other_visit/aviation_industry/...

But due to the way the regulators have devolved the standards compliance world wide there is very little chance that it will have the effect you and I want. If the paperwork is compliant then they are happy. MCAS on paper was compliant so they signed it off. What's actually going in the sims and the level of competence which is deemed acceptable they have virtually no clue about until an accident happens. Old days it was forced active prevention, now its reactive statements and finger pointing with a political input.

The pilots are the product of the system. You need to fix the system. The oem's, airlines and regulators don't want to change the system because that eats into profits and creates more work and expense for the regulator. Also the regulators are risk adverse. They have moved all the risk to the operator and oem's so if something ever goes wrong they can never be pinned for it and held accountable at a legal level.

Pax just want cheap tickets, they will not pay for anything which is over and above the legally required minimum standard. The minimum standard is set by the quality of paperwork thats audited by the regulator which these days is done by people that have never landed an aircraft of any size or changed a brake pack. Old school you had flight ops inspectors who were current on multiple types and Engineering assessors who turned up with dirt under their nails. Very poacher turned gamekeeper and knew and had used personally all the tricks in the book.

Its not saving a few bucks its saving millions if not billions of bucks world wide having the current setup.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Pilot training and simulator training.
This may be another can of worms.
Up until and after the second accident, Boeing had the only valid Max 8 flight simulator in the world.
The information provided to the simulator manufacturers by Boeing was faulty.
No argument. Boeing has admitted this.
After the first Mac Attack, Boeing issued a procedure to manually trim the aircraft.
Unfortunately the procedure didn't work.
I understand that the procedure did work in Non-Boeing flight simulators.
Dare we hope that the regulators are subjecting simulator performance to the same level of scrutiny as the aircraft?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

They will all have to be certified before any official training can be performed on them .

There is a order backlog of over 250 Sims but until they sort out the trim system they don't know what to put into them.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Quote:

They will all have to be certified before any official training can be performed on them .
Will the regulators be looking into this issue or will Boeing be allowed to self certify them again?
The question is not will they have to be certified as much as;
"Who will certify the sims?"

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Boeing can't certify Sims. It only provides the data pack.

I don't know much about the process. But it can take 3-6 months to get the first level approval. Then there are other levels for unusual attitudes, low vis training and zero flight time training. They follow on after it's been running for a period in can take 12 months from the boxes turning up until it has all the ticks in the boxs.

It used to be the OEM of the SIM got the base approval for the flight dynamics from the local regulator. But that's out the window now that the FAA is in disgrace with the other regulators.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Also, United has started buying used planes to make up for the grounding. Add it to Boeing's bill.

Link

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Alistair, Good - I was sure I had nothing to do with it. Not sure why you'd drag me into that.

Time to update the FCC to do a pop quiz from the memory item list for planes before allowing the pilots to use them. The time limit is 80% of the time the emergency is to be dealt with in real time, so there's no hesitation.

Would a "D" be an OK grade before being allowed to operate the aircraft or would a 100% be the requirement? And should the pilots get a second chance, unlike their passengers will if they fail? I'd say a 24 hour lockout on the plane would be fair. It would give the airline an incentive to ensure the pilots are trained to operate the plane. It might also weed out the pilots who panic under pressure and won't follow the procedures.

Make safety #1.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

It was definitely a comment made by yourself which highlighted the AP being at the same time as the stick shaker was running which I had missed. Anyway it doesn't matter how it got on the snags list as long as it gets sorted before the plane flies again. The trim issue is going to be by far the hardest to fix anyway.

Clean sheet designs these days don't have memory items. Because it's universally known that they are prone to human screw up.

My first type had 27 separate memory item checklists.

The cs300 has two which are put the oxygen masks on.

All memory item exams are 100% pass mark in my experience. And failure does result in grounding. And various penalties if you fail.

But due to the human responce not being consistent for the same person hour to hour never mind day to day even if the person passes it's no guarantee that they will perform as expected.

Some of the most spectacular falls from grace are with pilots who can spout every little number that are in the book. Bkiut put them in a sick aircraft they freeze and just can't process data. The only way you find out is the first time they have to deal with a full scale emergency. Which could be 10-15 years into thier careers these days if at all.

I suppose a fix could be increased training and testing for max pilots. Plus also a physical test every 6 months to make sure they are strong enough to deal with the control forces and have the stamina to turn the trim wheel manually.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

An interesting twist on the subject of pilot training is a development in the AF477 accident.

French prosecutors have started proceedings on Airfrance that they didn't train there crews sufficiently.

They also hadn't passed on warning material from airbus or complied with a mod to replace the pitot tubes which had a know issue in icing conditions.

This has the potential to change things somewhat more than the mcas debate on training.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Grounding a pilot from a classroom doesn't hurt the airline - grounding a plane for 24 hours because the airline didn't train a pilot does. It's more important that, in the moments before a flight, the pilots know what they are doing, rather than weeks or months before when they crammed for a test, after which they forget. And those tests don't cover the ADs.

I see that the French prosecutor agrees with me. No surprise that the airlines and some pilots are concerned. It seems to me that the prosecutor is motivated by the evidence from the MCAS initiated, pilot failure completed, crashes.

As to the comment - you'd been specific about it relating to the FDR diagram. My info was drawn from the text of the preliminary report, which the regulators could have read directly. It's nice that my post, copied and pasted from that document, was so critical to their ability to read.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

It will never happen that they will ground an aircraft as punishment.

AF pilots have mostly been through the elite school system in France which all the political types go through and also legal types.

The pilots got absolutely hammered for being completely useless. So the case is more political face saving by family connection.

If you get your way about training you will have basically killed the 737 and Boeing might as well not bother even attempting to fix it. It's such a cludge of systems hacked together from the 60's the training cost of keeping a pilot current on it will mean nobody will touch them with a barge pole. In fact it would kill the 747 off as well.

Plus the customers won't be happy paying the surcharge for the training.

But its nice in theory.

You would get better value training the engineers.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

If I get my way Airbus is gone. There are too many secret modes for pilots to identify what fails.

Another agency has pulled the tickets of multiple pilots over poor training. It looks like there's a trend.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"...Airbus....too many secret modes for pilots to identify what fails."

In the case of Boeing, that'd be MCAS.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Err the 777 and 787 are the same as airbus.
With the different modes and control laws.

All the fbw machines have them to be honest.

It's going to be a feature of all fresh sheet designs. Like it or not.

I haven't seen that little gem which agency was that?

I am all for the number of pilots being reduced. It will just mean I get paid more.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Apologies if this isn't the best place, but something which might be of interest to those in this forum is an illustrators site I found by accident.

He has hundreds of aircraft including most of the 747s, Alastairs Q400 and its a very interesting site. The original 737 is so small. if you want a particular aircraft click on any one then a search line opens up. Or just use google.

Q400 https://www.norebbo.com/2015/08/bombardier-dhc-8-4...
737 original https://www.norebbo.com/2018/10/boeing-737-100-bla...
737 neo (737 -800) https://www.norebbo.com/2014/01/alaska-airlines-73...
737 max (737-8) https://www.norebbo.com/2016/07/boeing-737-max-8-b...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I am now hearing a rumour that if they want to keep mcas then the whole flight control system will have to be certified to DAL A standards. Plus secondary independent powered trim stab system.

Apparently I was wrong in thinking it was a 386 processor which was over loaded. It's actually a 286 processor that they use.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Wow, a 80287 microprocessor. Its comforting to know the plane is controlled by a system slightly more powerful than an Atari, and programmed by contractors that are not familiar with aeronautical engineering.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

They didn't have anything to do with that side of things.

That was just a headline grabber.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

It's an 80286 variant, the '87 is a floating point co-processor. Compare to the computer in the LEM that put a spacecraft on the Moon and launched it back to lunar orbit. I'd say the 80286 is sufficient. It has an ugly instruction set, but it was created by the company whose founder also drove the adoption of the IEEE standard for floating point computation so that compilers could produce programs to create identical results for identical calculations and therefore support cross-platform software development.

The contractors work to a specification from the Systems Engineering group. If MCAS failed, it's the Systems Engineers to point the finger at. The Systems guys did the AoA that showed that MCAS was safe as it was implemented. 100% MCAS did what the Systems Engineers specified it should do.

There's no argument for blame about the CPU or the developers.

"Taking the 320 as an example, the ELACs are produced by Thomson-CSF around 68010 microprocessors
and the SECs are produced in cooperation by SFENA/Aerospatiale with a hardware based on the 80186
microprocessor." https://www.airliners.net/forum/viewtopic.php?t=13...

ELAC stands for Elevator and Aileron Computer; the 68k was what Jack Trameil put into his bare-bones Atari computers.

Too bad about the 68010; Motorola suckered a lot of people with the 68k series. Motorola could have done better, but they seemingly hated their customers. The 80186 was a dead-end from day-one; a better 8086 in a world that didn't want one. OK for cost-conscious embedded work, but not particularly powerful and less than half the transistors of the 80286. I guess airlines are always looking to shave a few bucks off of safety critical hardware.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I have zero clue about this side of certification.

From what I understand it's the Dal standards which are the crux of it. As soon as you start using multi thread and multi proc it's virtually impossible (nobody has managed yet) to get DAL A certified. So fbw they go for three black box's per critical system.

You have to tell the iPhone generation to slow down while inputting into the FMC because you can easily overload it and screw the sync up. So input wait for the effect then start the next command. That's what I know as a pilot of operating with this sort of hardware.

Problem is that with the Pandora's box that's been opened there is loads of things surfacing which don't meet certification standards that have been used for 30 odd years with no issues. So I presume they have to make a choice between changing the standards or enforcing them.

The likes of Boeing and Airbus don't actually make these systems. It's Collins and the like. It's not just a 737 max issue or boeing.

I have zero clue what fbw use as processor's.

The airlines have zero say on these systems. It's very rare they get a choice these days on any flight hardware. They don't even get a choice engines any more. Old days you had three choices for FMC none at all a low end 2d nav management system or a high end full management system which allowed 3d profile management and fuel.

These days everything is that intergrated and optimised for low fuel burn the development and certification cost are that huge its uneconomical in time and money to give options.

Btw there is as much testing going on at airbus as there is at Boeing just now. They have found a few things but only one AD level issue. But fully expect to find more. They just don't have the same pressure of being grounded.

Btw was it the Russian pilots getting thier tickets pulled you were on about?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Latest issue that's surfacing is there are objections to the fan disk being forward of the wings to such an extent that the wing root is not giving any protection to the rudder control runs.

As the engine is so new there is no data to be able to counter the possibility of issues.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Apparently, extending the landing gear of the 737 in order to accommodate larger diameter engines was already a topic 45 years ago, back when the 737 was getting its ass kicked in sales by the DC-9.
Check the third item under Sensor

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The blade did not enter the aircraft - the dinged window frame allowed the window to blow out and the passenger was partly extruded and then beaten to death by turbulence. Edit - it appears that part of the engine cowl is what hit the window, not the blade.

https://en.wikipedia.org/wiki/Southwest_Airlines_F...

The blade failed containment because the FAA does not require the cowling to contain shed blades or a cage over the front of an engine.

Interesting - the blade did not exit the engine in the plane of rotation, so the claim that a wing will stop a blade is stupid.

https://www.ntsb.gov/investigations/Pages/DCA18MA1...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Was that the only time a blade left the engine, Dave?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Waross,

Hardly - but if you are talking about turbine disk rupture then nothing on the plane is capable of stopping that debris. Worrying about engine position is a bit wasteful.

If you have a particular instance that is applicable to the 737 then bring the research.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The only control runs getting cut due engine failure I can think of is the soux city trimotor crash. Which is a completely different situation to the 737.

I can't see how you could protect against the hub going through the hull.

Maybe it's just a case of missing analysis/safety case.

The details are in the NYT it's a bun fight between FAA engineers, FAA management and Boeing.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Have the requirements been loosened? Blade-Off testing, where a fan blade is rigged to detach by a small explosive charge, is a well known technique. There are videos showing this test. The narrative mentions the difficult requirement to contain the damage.

Here are some links to assist.

https://www.sciencedirect.com/science/article/pii/...

https://www.avm-mag.com/video-showing-turbine-engi...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The requirements have not been loosened. In the SW fatality the blade shed caused the shell over the engine to be so damaged that a fragment was chucked hard enough to break out a window. That part of the engine is not subject to containment requirements and similar, though less energetic, damage has happened when latches were not completely closed, allowing the access doors to slam open and disintegrate.

I think a previous, non-injury, blade shedding, also SW, had the blade leak over the remaining front of the engine when the inlet cowl was severed, possibly by the swirl of a fastener in the deicing airflow, scraping and eroding the shell from the inside.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

the fan blade detachment and bird ingestion tests are the same as always. if the main hub comes off the shaft there is nothing going to stop it departing. Even in the RB211's that they use for power generation which aren't subjected to the same maint as the aero ones it basically rwrecks the whole generation house when they go. I think one of them managed to punch through the whole of an oil rig when one of the rear turbine disks separated. They never did find it.

its this sort of failure they are on about.

or this

Which is a airfrance A380 where the hub sheared off and they have recently found it under the snow.

This issue hasn't come from the pilot side of things. As far as I can tell the engineering grunts at the FAA had issues with it and flagged it and boeing had words with FAA managment and they were then forced to drop the subject.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I was once in essentially a p***ing match with a regulatory engineer. His job was to cancel the contract for-cause because the contracting agency wanted their money back to spend on something else and he was working at it by making up improbable scenarios. The one leveled in my direction was whether a few grams of polysulfide rubber might destroy the integrity of 5 pounds of cured polyurethane that was nearby (not in direct contact) in the few minutes it took for the catalyzed rubber to cure.

"Isn't it possible that something could happen? What have you done to prove that there won't be some adverse effect over the life of the item?"

Sure. Let me get on that 40 year life testing of a few thousand samples in every possible environment to see if two of the most stable elastomers will spontaneously degrade because they are near each other.

I have no doubt that certain parties within the FAA are looking to score political points by destroying Boeing as a way to advance their standing.

Obviously if one loses an engine the adverse torque from the remaining one will require significant rudder and it would really suck to have the loss of the engine cause the loss of the second. As the recent crash of the twin into a hanger showed, even a functioning rudder might not save the plane.

But looking at the potential arc of debris and the ability of it to leave the engine I doubt that a even carefully engineered experiment could sever any cables inside the fuselage. But hey, it's possible. A 1/2inch by 1 foot wide plate of maraging steel the length of the cable run on both sides of the plane will fix it. Sure, it means the 737 would be a one-across airplane, but think of how safe it might be.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

(OP)
I don't know why I'm encouraging this (somewhat) off-topic discussion, but...

How about I supply some necessary background info about the rotor-burst subject since it's so interesting right now:
https://www.faa.gov/documentLibrary/media/Advisory...
That thing is 45 pages and it's just the tip of the iceberg.
Hopefully that provides some anchor to the facts before anyone stirs up a rant about this particular failure mode. One that has nothing to do with the 737Max current difficulties, I might remind you.

The stuff in advisory circulars isn't mandatory, and says so in most of these documents, but if you AREN'T going to do what these AC's are telling you to do, then the FAA/TCCA/EASA expects you to come up with a really convincing explanation and an even better solution. It is also helpful to identify the zones to stay out of if, for instance, your customer wants to install some additional oxygen bottles but they happen to be close to the engine.

Take note of the date on that document: 1997. There weren't many events to learn from at the time, but enough that action was needed and a high proportion of them were catastrophic. The events cited in the posts above add 3 more examples. Each of the recent events could have been disasters leading to a crash, but in the end only one person died in only one of these cases. Bad, but it is a big improvement over the previous track record in the '60's to '80's, where an uncontained rotor failure led to a complete hull loss accident about once every 2 years. And that was a time with an order of magnitude less air traffic. I hope this is convincing evidence that there is a marked improvement in the safety standard in the 20 years since this Advisory was published.

One other point of interest, the example airplane they illustrate in the appendix is an actual aircraft type. Knowing which one makes this AC particularly useful when working on that type of aircraft.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"As the recent crash of the twin into a hanger showed, even a functioning rudder might not save the plane. "

Vmca roll overs will occur to every twin aircraft unless its a push pull engine setup. TO be honest with most light twins which are not pref A certified your better killing the second engine and landing in a field ahead if you can. Your playing with being spot on your speeds and getting 200ft climb rate. Go 5 knts slower than your blue line speed and your into V mca rollover and the only way to fix it is to reduce power on the working engine then accelerate and reapply it. The Q400 single engine, MTOW, temp ISA +30 at SL will give 1000ft per min climb rate, When you level off at say 5000ft it will overspeed if you leave the power lever of the working engine in the max power gate. There is another emergency range above the power gate which I have never used in 3 years not even in the sim. And the Vmca speeds and Vmcg are calculated at this higher MTOp and Emergency power settings so we have huge margins for error.

" One that has nothing to do with the 737Max current difficulties, I might remind you."

It's now part of the max's current difficulties. Even if they only have to "come up with a really convincing explanation" it adds to the time line and uses resources until its flying again. And there is also the possibility that while they are looking at that something else will surface. Its going to be interesting to see the list of out of certification items which were present on a fully certified aircraft for public transport.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

There is an interesting tangent on page 14 of the Advisory Circular.

Quote (AC Date: 3/25/97)

A pilot reaction time of 17 seconds for initiation of the emergency decent has been accepted.
The context suggests that a pilot reaction time of 17 seconds was already an accepted factor over 20 years ago.
When critiquing the pilots actions it is interesting to note that after the last unexpected Mac Attack, the pilots died with 2 seconds of unused, allowable reaction time.

There is another interesting point on page 5 of the Advisory Circular.

Quote (Advisory Circular 1997, Definition: Continued Safe Flight and Landing. )

Continued Safe Flight and Landin2. Continued safe flight and landing means that the airplane is capable of continued controlled flight and landing, possibly using emergency procedures and without exceptional pilot skill or strength, with conditions of considerably increased flightcrew workload and degraded flight characteristics of the airplane.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

waross, you forgot to highlight "possibly using emergency procedures", which is what the two sets of pilots failed to do.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I can delete if this is a re-post. This story summarizes pilot reports related to nose-down MCAS anomalies on the Max 8.

I found it interesting that at least two of the events occurred in strong cross winds which might be consistent with the way MCAS was implemented. Air passing across the hull and pushing up on one AOA sensor (the one being used by MCAS) could look like a high climb rate. Also that some pilots were having pre-flight cockpit discussions about the MCAS risks and contingencies I suppose.

Again, sorry if this is a rehash. I didn't see it in the previous posts.

Edit: It also seems that MCAS incidents were occurring while under autopilot and yet in the third or fourth report the pilot states that MCAS only operates in manual flaps-up flight.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

There is another system called STS which also has control over the trim stab. Which also adds to the confusion.

It is perfectly normal on the NG for the trim stab to be moving none commanded by the pilot while manually flying. Which adds to the issues of realising that its moving incorrectly.

"which is what the two sets of pilots failed to do."

If two sets fail to do in such a short period of time you can garantee that a whole load won't do them either given the same range of indications in the cockpit.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I think it is pretty obvious at this point that skilled and well trained pilots may have averted both incidents, and probably have averted similar incidents.

Does that degree of skill and training represent, say, the second or third standard deviation of pilots in the air these days. With all the talk about response times and poorly documented maneuvers to unload the elevator, I think probably not. If you add physical strength requirements to operate the trim wheel in a worse case scenario we may not even be in the first standard deviation. As has been pointed out, pilots these days are more operating the plane and less flying it. That means that system design should tend more toward fail-safe, redundancy, low-strength input for recovery, longer response times, etc.

For the sake of posterity we should understand what mistakes were made by the pilots. The op-eds and 60 Minute pieces that white-wash any fault of the pilots might be useful for pressuring Boeing but they aren't doing any favors if they don't result in pilot improvements as well.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

This is kind of sad https://gizmodo.com/turn-it-off-and-on-again-every... apparently, certain older A350s have to be power-cycled within 149 hrs of a previous power cycle, or the controls might get wonky...

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

There are always mistakes made by pilots.

Niel Armstrong with all his NASA training made a mistake landing on the moon not turning a radar off and overloaded a computer so he had to fly manually.

Sully didn't run the ditching checklist.

Training is good and things will change. But if the 737 max requires more training than other types then it's dead as a Dodo. They might as well not bother getting it flying again and scrap what they have built.

There would be zero point me doing any of the stuff that's required for flying a max with a dodgy flight control system with ineffective manual trim.

31st of October is a crucial date. Alot of the purchase contracts have cancellation clauses in them that if the plane isn't delivered by then the order can be cancelled and deposits have to be returned.

This power cycling thing is a feature on quiet a few types. The Q400 I always do a power cycle when I take an aircraft over. It only takes 5 mins to come back up though. The old ins systems did used to take a long time to come up. Modern laser gyro ahars is under 60 seconds for them to come up and align.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

(OP)

Quote (Alistair Heaton)

There are always mistakes made by pilots. ... Sully didn't run the ditching checklist.

What? Alistair, you are normally so fair, why the sudden slap?

Sullenberger made a conscious decision to touch down at Flaps 2 not 3, to have a higher nose attitude, because he anticipated that the fly-by-wire would not let him flare nose-high enough with Flaps 3. That was later confirmed, and it was also later confirmed that despite dual engine failure the hydraulic system had enough pressure to deliver the Flaps 2 settings as he commanded.

The other item on the checklist that Sullenberger skipped was to set the parking brake to ON.

For the record: I can forgive him for skipping that, while afloat on a river.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

He didn't run the ditching checklist which meant three pressurisation large volume flow rate valves weren't closed so it flooded with water alot quicker than it should.

They were full of fuel so that saved them.

I have zero issue with what they did. Btw he is a check airman on 737 500's and knows the plane extremely well. So if he says he can understand the pilots confusion he knows what he is talking about.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

It didn't help that someone opened the rear exit doors.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I have a bit of confusion about whether the pilots followed the checklists correctly.

AFAIK the runaway stabilizer trim memory checklist doesn't require reducing power. It also has using the electric trim to return the stabilizer to an "in-trim" state before cutting power to the trim system as optional. The pilots did neither of these things, one or both of which could have saved them.

Is my understanding correct (based on current published info)? If so, that would mean that they did follow the checklists. Are there other issues with the lists under contention?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

We've discussed this quite a lot if you read the previous posts. The AD was rather vague and not a checklist in itself as it hadn't been added to the QRH AFAIK and said you could use the electric trim before operating the cut out switches, but not to where you needed to get them.

Now we also don't now know if the electric switches were working correctly due to possible overload of the processor so maybe the ET pilot moved the trim as far as it would go then decided to cut the power to prevent further nose down.

The speed certainly didn't help but even at a slower velocity, the force on the smaller manual wheel from earlier versions of the 737 and the number of turns required may not have been physically possible. This was included as a default manual operation available in theory at any time, but in reality didn't seem to be available to the pilots on ET.

The reduce speed and roller coaster operation wasn't in any recent handbook or manual.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The other parts are arguable but it seems that they did turn the switches back on, which the AD clearly stated not to do.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

What they actually did in the cockpit is now deemed unknown due the the data system issues and processor lock up.

The FDR data is now deemed un certified because it's recording the effect output not the cause in switch movement.

The whole thing can only be described as a complete and utter Custer f*CK

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The "Processor lockup" is from an artificially applied change. The lack of detail confirms for me that it had nothing to do with the accidents. More particularly, if there was processor lockup there could be no command from MCAS; we know that is not the case.

There is never a way to determine if a switch moved until they put video cameras into the cockpit.

What is known is that every potential cause of an action resulted in a reading of results.

Eufalconimorph - Before there was runaway trim the initial problem was airspeed disagree, which does require reduction of power. It says trim as required. Trimming was required. The Ethiopian pilots chose not to. In five months of warning it is clear that neither pilot went through the steps enough to act correctly on trim runaway and never learned to manage airspeed disagree. Which is no surprise - the airline has concentrated on rapid expansion above all else. Greed and pride.

LittleInch - trim is always the same - reduce the load on the controls so the plane remains pointed wherever the pilot points it without having to push or pull or turn the controls. The various estimates are that the Ethiopian pilots turned off the trim with nearly 50 pounds of pull required. Imagine if someone set a 50 pound bomb on your arms while you are typing and all you had to do to make the bomb go away was press the space bar. Instead you power off the computer and sit with the weight of the bomb on you and when you drop it - boom. Yup, as easy as the space-bar. Waiting for the CVR to see if there was some reason they decided to muscle up on the plane rather than push their thumb on the trim switch.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

It appears that they followed the AD until it became apparent that the AD instructions didn't work.
When they realized that if they continued to follow the AD they would probably die, they tried something else.
It almost worked and it could have worked if they had been aware that there was another Mac attack waiting for them. and turned the switches off between the short electric trim up commands.
Did Boeing or the FAA share that information with the pilots?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Grab a copy of the preliminary report. It has the AD but it doesn't have a copy of the airspeed disagree procedure. That's an initial cover-up as airspeed disagree was ahead of the MCAS intervention.

No sequence of steps was correctly identified by the pilots and no sequence of steps performed matched the airspeed disagree, the AD, or the runaway stabilizer procedures. They picked a few items out of order that happened to be on them.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I agree processor lock up is unlikely to be a factor but we might never know for sure. Quite the opposite to be honest if it locks up it may be processing only MCAS commands and not the manual trim inputs. ITs not a fail safe with zero output when locked up.

The STS has the trim wheel moving constantly right after rotation. Its not the case that the trim wheel doesn't normally move during this period unless the pilot commands it. The whole point of these systems is the aircraft is never trimmed correctly on purpose and the pilot gets weight feed back on the stick. Even if the pilot does trim it perfectly for zero force finger tip flying the system moves the stab to induce a slightly out of trim situation. The only way to know what's right and what's wrong is via session in the sim. Reading about it on an Ipad is pretty much useless.

Switch positions are wired directly to the FDR for some flight critical systems. The cvr is that sensitive that you can hear switch movement. And comparing the sound track from the ambient mic and the two headset mics means they can work out the location of the switch moved but its not exact.

When you say the intial problem was a airspeed disagree thats not the full story as we are pretty sure that it was a bird strike. And to rip the AOA vane off it must have been a big one. So prior to things happening in the cockpit they would have seen a large bird apprently about to enter through the front window at 240 mph. So they more than likely had there heads down. Then a colossal bang and then things start going off. The startle factor would have been huge. Damage assessment after a bird strike is seat of the pants stuff you basically have to check everything then cross check everything to see whats valid and whats not. There is no QRH listing for it on the Q. They would have been proritising checking the engine on the side that the bang occured for more than a few seconds after they had got over the shock of the bird strike more than enough time to go over the 8 seconds responce time required to keep the aircraft in controlled flight and be able to manually trim.

I don't actually see the MCAS system as the primary issue to get the 737 MAX flying again. The whole trim system needs to be sorted and I can't see a software fix ticking the boxes. I also now can't see it flying again by next summer season.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The computer overload may have been a slow down rather than a lockup.
We saw that when computer control was first introduced to industrial control systems.
Input signals (switch operations) are stored in a buffer. The computer deals with each input in turn.
It was quite disconcerting to push an emergency stop and then have to wait a number of seconds for a motor to be de-energized.
A small program may execute with negligible time lag.
However as more functions are added to the workload, the response time may start to increase.
There may be a time lag between information arriving at the buffer and the information being read from the buffer.
Then there may be a time lag between an operation being read from the buffer and an output being generated.
When why and how much delay in execution of commands is system specific and also may depend on the order of instructions in the program.
I realize that this may have nothing to do with the computer problems on the Max.
It is, however typical of early industrial computer systems that an increase in the work load often results in slower response times.
Yes, my information is very old. Almost as old as the 80286.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

On the business side it looks like this is having the impact predicted.

https://www.theguardian.com/business/2019/jul/29/r...

Now over here not many people are weeping too much about Ryanair and the indomitable Mr O'Leary, but it will impact on pilot and air crew numbers.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

(OP)
The Seattle Times has crammed so much advertising and tracking on all of their 737 articles, I can barely get their articles to load any more.
Thank you for the link - I did eventually get to read it. Cosmic rays triggering errors in microprocessors... They're really checking everything, aren't they?

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Alistair, thanks, that was a good article. The cosmic ray is only for single bit flips, which is a pretty common problem that requires design mitigation for LEO satellites. The scenario described in the article is for 5 arbitrary bit flips, which would be extremely unlikely. Nevertheless, the article at least clears up the incorrect claims that the processor froze or slowed down; it was simply that the pilot's recovery procedure took too long and the solution is to run both processors in parallel so that any disagreement will result in reversion to manual controls.

btw... ad blockers work great; if there were any ads on that site, I didn't see any; still took a while for the photo at the start of the article to show up, but's probably because it was queued up after all the ads that were blocked.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

That's pretty normal spar. Everything goes on a vibrator for an hour as well both high G and low G huge deflections and Up and down the frequency ranges.

Its not only cosmic it is also part of the hardening against mobile phones.

Both these accidents occurred below 10 000 ft so its extremely unlikely it had an effect.

If its parallel procs then that a whole heap of further testing being required. I think the trim issue is by far the hardest to crack.

The other tip with these articles is to read them in a private window. It then stops all the data analysis scripts running and your data being sent.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Quote (Alistair)

The other tip with these articles is to read them in a private window
Thanks for the tip Alistair.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

it also removes the max number of articles a month limits.

Time for a new thread again?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Alistair - mobile phones? That's a jump. Anyway, as I suggested before the FAA simply added onto unlikely things to make sure a failure is seen. If it took 8 bits or 20 bits or setting fire to it, they would have done so.

Instead of blaming MCAS how about blaming the false stall detection that should never have been triggered in the first place? Without that false information MCAS never triggers, and the poor crew is never startled by the stick shaking and annunciators.
With the changed software will the plane revert to manual on an AoA failure and leave even less qualified pilots who cannot manage the trim any better than these crews did to crash even less encumbered planes? For certain that's exactly what happened on AF447. To be fair, in AF447 it required special software to ensure that one pilot who should not be flying gain command over the other. That particular fault won't happen in a 737, but in the case of ET302 it is clear that neither pilot was prepared for manual operation. Both "voted" to crash the plane.

I saw a suggestion that shutting off the ADIRU with the failed AoA sensor would have forced the FCC to roll over to the working unit and operate MCAS correctly. That appeals to me as it means that the MCAS protection still functions without stepping over the trim system. The chance that both AoA sensors are destroyed is fairly small, but it still depends on pilots knowing enough about flying the plane to be sure to shut off the actual failed unit. Lots of accidents where a pilot gets an alarm in a twin and feathers the good engine, crashing the plane almost immediately, so maybe pilots knowing which side of the plane they are sitting on is a problem.

Shutting the bad ADIRU off would have been the better answer than the AD. No need for judgement or remembering a list.

Others have suggested the ADIRU itself could tell that the sudden jump in AoA with the WOW switch off is enough to flag itself out for being unreliable. No 737 is operating above 35 degrees of AoA in any meaningful manner and cross checking that with the other unit would confirm, if the rate of change is lower.

As to the trimming answer. 100% disconnect the trim wheel cables from the trim jackshaft and just use a redundant motor. Add switches or valves to the trim wheels like they seem to have on the fake wheels on Airbus planes. They can make the redundant motor hydraulically operated and get rid of the trim position indicator that pilots obviously never bother to look at anyway.

With MCAS handled in software and years of this one-motor, cable drive trim system functioning as-is on the NG, make the alteration a roll-in option for changing the existing Max hulls and a requirement on new hulls produced after 6 months. This will let Boeing ship what they have, gracefully slow production to give time for testing a system not much different than Airbus uses already, and not increase the risk to passengers over what's been seen in the NG for the last 20 years. When already built Max hulls come in for major maintenance, overhaul with the new system.

And maybe the airlines can finally come clean about how they don't really train pilots to handle problems, but to wring out every dime in fuel they can get by abdicating piloting responsibility to a chip of silicon under the floor to get minimum fuel burn.

Just kidding. Airlines won't ever admit fault or take any steps to correct this negligent oversight. The only ones who can are the governments where they operate, and national treasures don't get criticized. Which is why Ethiopian has not produced a video or document of any of their pilots having done even one second's worth of MCAS consideration after the AD was published.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

They do actually effect things, thankfully on more modern aircraft its limited to an annoying did, did, dit on your headset in the front.

Not so long agon they used to trigger the fire alarms but most of them that were susceptible have been replaced now.

Your thinking along the same lines as me now. They may get a rolling upgrade path in the usa regulators but maybe not after the hit to thier reputation. But no airline will take the risk of accepting a max. And you have zero chance of easa and the Chinese allowing it. If they do take delivery and more things turn up your stuck with a dead duck.

The NG, one of the disconnect switches killed the electronics but left the electric trim working. It also has a control force cut out switch so if the pilots pulled or pushed hard enough it also killed the electronics but left the electric trim working.

The airbus wheels are not fake apparently but they are pretty much useless until you get to the very bottom basic control law. Airbus is never out of trim until that last level. There is no manual trim wheel on the Q400 but as its not a stab the control forces are low enough you can fly it across the full range of the operating envelope at max trim either way.

At least 18 months to get your list sorted and certified.

The airlines will always say they provide the legal requirements for training. And most of them it will be the legal minimum. Some of us are lucky and get more than the bare minimum.

It's the regulators you need to convince and enforce training. Then everyone is operating to the same cost base.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Naw. I'm thinking along the lines that people like you are sitting in the FAA and EASA looking to score a kill and Boeing is going to have to bleed a lot to make up for badly trained pilots and that those regulators failed to do anything about it.

The NG still has exactly the same trim wheel problem, but somehow zero accidents related to it. The number of switches doesn't matter. If a fault in an NG had run the stab trim for more than a few seconds in the hands of that Ethiopian crew everyone would have died just the same. MCAS became a pass-fail test of whether pilots had ever trained.

The Airbus wheels don't require force just like the control sticks don't. They could have used paddle switches, but used fake wheels instead, no doubt as a cost savings measure for compatibility with training on some long extinct type.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Just confirmed it on the airbus there is definitely a mechanical linkage to the trim stab setup.

Yes there will be loads of people like me. But its nothing to do with taking revenge on Boeing or the USA. Its just wanting a safe environment to work in, with realistic expectations about human performance.

I have never flown a Boeing or an Airbus.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

All the Airbus cockpit photos show only a tiny portion of a wheel exposed. So lets get an Airbus to full nose down trim and see how easy it is to move the wheels.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Extremely easy. Until you get all the way down to mechanical backup. And even then there is power assist on it aka power steering on a car. So you would need a failure of all three hydraulic systems and no electrics to turn it into a 737 max.

Finger tip stuff.

http://www.airbusdriver.net/airbus_fltlaws.htm

Even in dual engine failure with the RAT out you don't go to that law.

Its only there to give you control while the electrics come back online and the computers come up. You can't land using it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Gotta be full failure. So I guess that's a nope, the trim wheels won't help. If the software fails from cosmic rays bashing a bunch of bits, so be it. Ground Airbus until this is a dealt with.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

That will be the 777 and 787 grounded as well then. Along with all the E jets.

But as FBW system don't rely on the pilot as the secondary back up system for any of there flight major or critical systems unlike the 737 max in fact with the A320 the pilot only gets involved at the 5 or 6th redundancy level then I suspect your wish will not come true.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"Instead of blaming MCAS..."

Of course there will be other contributing factors, but it is clear that MCAS will ultimately shoulder most of the blame.

('most' = roughly 60-80%)

But it is nice to see that they're uncovering other somewhat unrelated deficiencies along the way. Prevention of future incidents sort of makes up for it requiring two MCAS incidents to respond appropriately.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

There is a small percentage of people out that see this issue as purely a pilot issue. There is a similar sized number who see it only as a hardware issue.

There is another group which is more interested in shafting the FAA.

Another group which global politics are driving their feelings.

Then there is the accountants/finance types, quiet what they thinking while they run around in circles I do not know. But it more than likely centres round bonuses and making sure the finger pointing doesn't finish pointing at them.

Then there is the majority of us that see it has a failure in regulation of both certification design and training standards. The politics of how Boeing runs itself are of zero interest to us.

Like it or not this has and will continue to effect the global aviation scene for the next 10-20 years. Short term alot of people who had nothing to do with this will be without a job. And then there are some of us who will make quiet a bit of money out of it basically covering the hole the MAX has left. I suspect Airbus pilots in the US are flying their backsides off along with technicians trying to get old classics airworthy again.

The word on the street is that the max is not expected back in service by the next years summer season in the EU. Wetlease contracts are currently being negotiated but crewing is proving to be problematic. More than a few are hoping Ryanair do sack 900 crew. If that crew then go airbus rated then that's another knife in the back to Boeing operators because they won't get them back.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

(OP)
AH,
Thanks for the stall training and modelling article. Interesting to read that even airline pilots can be overwhelmed. That Figure 6 is a real "bad day" for someone.

Reminds us what is meant when the regulations demand that some maneuvers and pilot reactions cannot require an unusual amount of skill to complete.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Of course we can be overwhelmed. And there are a huge number of variables which effect when you hit your 100% capacity point. It changes day to day and also during the day. Experience plays a part. In the sim they kill the Captain to over stress the first officer. For the captains they keep the FO alive but tell them to question every decision. Killing them usually makes life easier.

Figure 6 was your standard minimum height loss old school American stall recovery with min height lost. I won't bother repeating what I have said previously on the subject. But its now been changed after FAA and NASA study's but its taking time to filter through to the whole of the pilot population mainly because the old timers who hold training and examination positions really don't buy into it.

As you can see though its a pre briefed exercise on a standard exercise which is trained for regularly in the sim, it is also an exercise which is part of the initial PPL single engine training. Per say it should be at riding a bike level of muscle memory.

Its a realistic model of human performance and reaction to stimulus that quiet a few of us are hoping is going to come out of this.

And a real definition and method of measuring situational awareness.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Figure 6 is what I hope is a now former pilot. They have negative skills.

Accessing the trim button on the control wheel had better not be an unusual amount of skill.
Cockpit Resource Management had better not be an unusual amount of skill either.

Was anyone of the impression that receiving an AD, glancing at it, and then setting fire to it in the garbage bin was a sufficient skills compensation response? The next sales contract needs a check-box for "Our Pilots Don't Read" so the AD can be issued as an audio book or a video with content cotrols that requires a pilot's license number to access and content based questions before indicating that the pilot had any contact with the material.

Thankfully Airbus has had unusually skilled pilots.

On 5 November 2014, Lufthansa Flight 1829, an Airbus A321 was flying from Bilbao to Munich when the aircraft, while on autopilot, lowered the nose into a descent reaching 4000 fpm. The uncommanded pitch-down was caused by two angle of attack sensors that were jammed in their positions, causing the fly by wire protection to believe the aircraft entered a stall while it climbed through FL310. The Alpha Protection activated, forcing the aircraft to pitch down, which could not be corrected even by full stick input. The crew disconnected the related Air Data Units and were able to recover the aircraft.

More detail here - http://avherald.com/h?article=47d74074

Airbus/EASA issued an AD telling pilots how to handle the situation. I guess Airbus pilots are believed able and willing to read, so no one called for grounding them world wide before the full fly-by-wire implementation was given a look-over, including improbable injected situations.

This was clearly a case of unusual skill in that no procedure was in place to shut off a key component that is critical to flight management. They managed to get it sorted in about 60 seconds. If the current thought that a plane can be ignored for 3-5 minutes and still must be easily recovered while ignoring the relevant AD steps then Airbus should be in great trouble for taking shortcuts in their software.

Tell me about the superior software developers are AB and how EASA won't let garbage get through.

No wonder Airbus has kept their corporate mouth shut about pitch trim software. They did it first.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Figure 6 lost 1700 feet vs 600 in figure 5. That's not "minimum" that's almost 3X.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

No he won't be, I suspect he was a 50 year old check airman. But he could have been a management type as well.

The old days the check airmen wanted less than 300ft height lost. Which from what I could see, usually resulted in multiple secondary stalls triggers in the process. The UK way I was taught we use less than 1000ft and any secondary stall more than a brief blip was more of an issue than height lost. I must admit years ago as a FO I think on my second sim check after starting flying multi crew I found that if I just stick the pitch to 2 deg nose up pause for a fraction of a second roll the wings then progressively increase the power to max. Everything just works. And its worked for 3 different types now. It wasn't something I had been trained to do it just seemed obvious its what you have to do as a Engineer. With the Q400 it gives 500ft height lost and no secondary stalls.

Bombardier, Embraer and Airbus are all keeping there mouths well and truly shut on the subject and are more than likely putting significant effort into testing as well. And as Airbus has already issued a AD on the NEO I suspect they are finding things as well.

I wouldn't say the Airbus pilots are any more skilled its just that the training for Airbus is different. The initial airbus rating is getting on for twice as long as other types and its hellishly expensive. They spend nearly a month in the classroom alone on the airbus philosophy and system method. But once they have gone through that the differences training between even a A320 and A380 is surprisingly short. They have a set procedure for the system going crazy which basically kicks it into alternate law which so far has always saved the day.

I will admit airbus were lucky, if it had killed everyone onboard then the response would have been different I suspect. But even then it would have still been less than 1 event in 1 million flight hours so technically it was still within certification limits. Af it was pretty obvious that 90% of the reason why everyone died was pilot error.

MAx two fatal crashes in no where near 1 million flight hours. No chance.

To be fair Concorde was killed after 1 fatal crash. So its not as if the MAX is being treated any different to any other type.

The current thought is not to be able to ignore anything for 3-5 mins. Its to give the pilots data which can allow a timely identification of an issue with a high success rate of getting the right one and fix it before the aircraft leaves controlled flight. And while going through this process the plane remains inside a recoverable envelope.

Your idea on competency levels would cut down the number of crashes I will admit. But that's mainly because there will be a fraction of the aircraft in the air that there are currently.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

2
"Accessing the trim button on the control wheel had better not be an unusual amount of skill."

Too bad about this:

Boeing altered key switches in 737 MAX cockpit, limiting ability to shut off MCAS

Odds are high that the design of that panel (and its associated wiring) will have to be changed so that the MCAS can be disabled while retaining the manual Trim switches.

Speculation: Perhaps it'll need to provide MCAS Disable and Electric Trim disable on separate switches. That would make sense, at least in concept.

This may prove to be necessary because of the previously-noted issues surrounding the manual Trim Wheels. Presumably redesigning those would be too difficult.

There's an argument to be made that the AD wasn't perfectly clear, specifically with respect to the required sequencing. It can be predicted that the final report will include criticism of that wording.

---

The strident efforts being made in this thread to deflect blame onto the pilots might be more effective if occasionally accompanied by a trace of balance. Narrow one-sided opinions tend to be discounted.

This is offered in the hope that it'll lead to an improvement in the thread content.

Apologies in advance if it causes offense, but somebody needs to mention it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

VEIBLL

That issue has been noted before on this thread, probably in part I or II and mentioned more than once.

The interesting bit is that the report says no one really knows why there were two switches, side by side as none of the current procedures tries to get a pilot to flick one and not the other, but both at the same time.

I think it is potentially true that if the ET pilots could have re-energised only the thumb switches, then the likelihood of survival would have been increased, but we'll never know.

For this to work (MCAS / AP only disable of the stabiliser ) they would need to place the two switches some way apart I believe to prevent inadvertent operation of the wrong one.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

MCAS is to meet a maneuvering characteristics requirement. That's why it cannot be separately shut off. The wheel trim switches override MCAS instantly and reset the timer; there was never a need to let the plane get out of trim in the first place.

The ET pilots did re-energize the thumb switches and then they failed to actually move the stab more than a tiny amount; no doubt because by then the air loads were so high and they were so far outside the normally allowable speed envelope that the small change in trim was like a kick in the butt to the pilots and they didn't want that. Then, having concluded they would not use the trim they left the system armed instead of doing what the AD said and never re-energizing those switches.

The AD is clear. Trim the airplane before shutting off the motors. They had 5 months to ask for clarification, but if one never bothers to even walk through the procedure there will never be any questions. Any of the pilots for Ethiopian could have walked it through and then taken that info to the chief pilot to carry that information to all the others. Never happened.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"The AD is clear. Trim the airplane before shutting off the motors."

You are incorrect on both points.

It actually emphasizes ensuring that the STAB TRIM CUTOUT are set to CUTOUT first. Later, in a note, it allows what would be a contradictory back pedaling to switch the system back on.

You may review it here.

Extracted from report.

This unclear and out of order wording will almost certainly be a point of discussion in the final report.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

To be fair there is some justified blame towards the pilots.

But as they are dead now there is not a lot they can say or do in their own defence.

And even if we were all to agree that it was the pilots fault it won't now change the status of the 737 MAX or allow it to fly again with out it being recertified.

The how and why it came about that the authorities revisited its certification and found it lacking really won't change the current situation or for that matter the changes that are required before it can fly again.

Something has to be done to restore confidence in the airframe for the pax never mind pilots. If the pilots arn't happy they will say so and if the pax hear the pilots they definately won't be happy to fly on it. So the type is dead anyway.

Anyway the sorting out the manual trim system hasn't been mentioned yet offically. Thats going to be the real killer. They might be able to get it past the FAA (but I doudt it) but the rest of the world won't accept it unless its changed.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"MCAS is to meet a maneuvering characteristics requirement. That's why it cannot be separately shut off."

Incorrect for multiple reasons.

The panel designer would simply specify a guarded switch. If engines can have e-handles, then the MCAS could have its own cutout switch.

MCAS can be shut off. So your first sentence fails to explain the point you claim about 'separately'.

The likely reason it didn't have a separate switch is that the very existence of MCAS would have to be explained. Which apparently was to be avoided.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

There is uncommanded stabiliser trim inputs all the time on both the NG and MAX.

The other STS system is constantly changing the trim while manual flying. At no point does the trim wheel stay still unless the pilot actions the thumb trim switches.

There is also no indication when the STS is in action or for that matter the MCAS is in action.

It isn't the case that you can say well I haven't pushed the trim button and its moving, hey we have a problem.

Its a case of spot the difference in movement.

This is all while trying to recover from a big bird hitting near the cockpit windows at 250 mph. Mutiple alarms going off etc etc.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"...some justified blame towards the pilots..."

I believe that point has been mentioned once or twice.

There's certainly some truth in it (there always is), but when it's single-mindedly used to deflect blame it becomes an issue.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

STS offsets control loads. The difference is spotted because the yoke isn't pulling you out of the seat; the yoke is not doing anything the pilot isn't doing to it. When you get to 50 pounds of pull or so a pilot should probably have some clue the plane is out of trim. I can see how a Q400 pilot would not know this. It's really easy - if you find the controls on a heavy jet are pushing or pulling far too much for the maneuver you want it's a good idea to use that trim switch and maybe see if the plane is out-of-trim, especially if, just 5 months ago, there was a mass casualty crash that was related to being out-of-trim.

There's also just one PF. The second seat can monitor the instruments, including the trim indicator, which would be a handy thing to do with a false stall warning going off. The PF can just ask "are we in trim" and the second seat can look.

Alistair - where have you heard the bird strike on the CVR so you know it was a large bird? You previously commented they saw the bird before the collision; do you have link to that video?
---

First, MCAS cannot be shut off because it is to meet a requirement from the FAA. This is particularly true since it is to operate when all other automation is shut off to discourage pilots from approaching stall under manual control. It's like a switch that disables ABS on a car. See any cars with that switch on the dash-board?

Being able to shut off the trim motors at all has been a point of contention. There should never be a need to shut MCAS off; had there not been a false AoA detection MCAS would not have needed interaction.

Second, MCAS is a software overlay on the Speed Trim System. It's not a separate thing. There's no MCAS unit in the plane so MCAS has no individual shut-off. It can be overridden using the electric trim switches. That was known as soon as the Lion Air report came out.

While the instructions are out-of-order the steps presented are not.

"Electric stabilizer trim can be used to neutralize control column pitch forces before ..."

That's why a walk-through even once by the pilots would tell them what to do. They never did. Like those times a test is given and people are told to read the entire thing first? Be a professional and read the entire document, make a plan of action, rehearse that plan until it is second nature, work with the other pilot to confirm that the rehearsal is correct. Things competent pilots should do.

I am correct that, if anyone thinks this document was unclear, the ET pilots had 5 months if they also felt it was unclear to get it right. Had it been written as total gibberish they would still be 100% responsible for not asking for clarification.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

3
3DDave, I do not have a dog in this fight, so to speak (it is actually a cordial professional discussion), if you have any personal stake to reduce the culpability of MCAS and those responsible for it, now would be a good time to come clean. If you are truly disinterested, that's cool, stick to your guns.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

" It's like a switch that disables ABS on a car. See any cars with that switch on the dash-board? "

Yes and also I have a C+E license and you can turn the ABS off on 40 ton artic's as well.

I also have a button to turn the traction control off on my 3ltr turbo Merc E class as well. Which is really stupid thing to do especially with a trailer on the back.

It could be that EU design rules require it or litigation in the US means you can't have it.

We don't know if the pilots did or didn't walk through it. To be honest response in simulator after reading new emergency SOP's very rarely occurs as it should do. It usually takes a years worth of sim checks before things become predictable if the situation occurs. Is not uncommon for go-arounds to not go book standard. And we do at least 5 of them every time we are in the sim. Usual mistake is to miss to putting the gear up.

"The difference is spotted because the yoke isn't pulling you out of the seat; the yoke is not doing anything the pilot isn't doing to it. When you get to 50 pounds of pull or so a pilot should probably have some clue the plane is out of trim. I can see how a Q400 pilot would not know this. It's really easy - if you find the controls on a heavy jet are pushing or pulling far too much for the manoeuvre you want it's a good idea to use that trim switch and maybe see if the plane is out-of-trim, especially if, just 5 months ago, there was a mass casualty crash that was related to being out-of-trim."

You have never flown an aircraft obviously. I have flown jets in the sim. There is no difference in control forces between turbo props and swept wing jets apart from the zero force FBW machines which I have also flown in the sim. Everything heavier than 15 tons has powered controls and a feel unit and they are all about the same. The input responce is the same. Hence the requirement for MCAS. 50lb's does not pull you out of yourseat. With adrenlin kicked in which this crew will have after a great big bird just battered off the hull the human strength system is in uncalibrated mode which can mean you break bones. Its pretty well documented that 60kg cabin crew can bend door handles that are jammed. They had to change the stick I think it was on the F16 to make it move after they intially had a fixed stick. Apparently one of the test pilots broke his wrist trying to move it. And because it didn't move and he wasn't seeing an effect he just kept putting the muscle power on and then his wrist snapped. There are also multiple cases of mothers lifting cars to rescue children.

BTW guys don't be worried about people sticking it onto the pilots its pretty much standard policy of OEM's to do this after any incident. And if that doesn't work they go after the maintenance. Only only eventually kicking and screaming will they change anything As VEIBLL points out there is always an element of truth in it it as well including the maint. This case though is extremly unusual because of the shear volume of issues with the original hardware. The pushing of the its the pilots fault really will have zero effect on the resultant outcome now. The trying to put it back onto the pilots is like flogging a dead horse.

Why engage with it?

Because you won't change the mind of the person saying it. But especially in this forum a balanced reply stateing the issues may make another engineer in another disapline think human factors and put a bit of thought in how the operators will interact with their design in both normal and none normal operation.

To be honest if you put this situation against Three mile island from the human responce perspective there is a remarkable number of similarities. To this day there are still issues with reactor operators turning emergency cooling systems off because the "pressuriser will go solid".

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

On another note there is issues found on the A320Neo as well now.

https://www.aerotime.aero/ruta.burbaite/23782-easa...

And more than likely someone will say ground them.....

It hasn't killed anyone, when the issue does kill someone then they will ground the type.

But its good to know that they are actively testing all types now.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

To me, it does seem odd that pilots flying the MAX wouldn't ensure they understood exactly how to recover from a MCAS issue after the first crash, not just hope they could figure it out.

I'd personally like to see the picture of that ABS disable switch. Seen lots of AH and TC disable switches on passenger cars, but never an ABS disable switch.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

ABS, not traction control. Many cars have traction control cutouts. But the question was ABS in cars, not trucks or some other vehicle. I am surprised that articulated trucks have maneuvering feel regulations for their design and operation, because that's the only parallel that makes it worth mentioning it.

I didn't say the nominal control force was different - You went out of the way to say the Q400 has no stab trim, therefore you could never feel a stab trim problem, unlike heavy 737 pilots, who would. If you think holding a continuous 50 pounds is not a big deal when you are expecting 0 pounds, I cannot say anything about your personal ability to ignore such things, just that if I had a 50 pound sack of cement set on my outstretched arms while driving I would notice it, regardless of an engine warning light or a buzzer.

If you feel like 50 pounds pull in level flight is fine, that's up to you, but for everyone else I think it would be quite noticeable.

Boeing is going after their own problem. But airlines and pilots are trying to ignore their own massive failure in this pair of tragedies.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Quote:

BTW guys don't be worried about people sticking it onto the pilots its pretty much standard policy of OEM's to do this after any incident.

That's true for almost any hardware or software, not just planes. Just try calling up product support for your laptop, or whatever; the support centers have scripts that cover 99% of the cases, and they're all configured on the assumption that the user did something wrong; "Did you check to see if the power cable is connected to the computer and the plug is connected to a wall socket?" Until the script finally concludes without a solution, several times, with different "technicians", only then will the call center pass you on to a "real" technician, "Oh yeah, we boffo'd your DSL speed; it's outrunning your connection."

In most cases, the human operator is the fallible one, not the hardware. When you consider the cases where American astronauts lost their lives, there were hardware failures, but what allowed the hardware failures to be fatal were fallible human decisions to fly a Shuttle in colder than specified weather, thereby allowing the o-ring seal hardening in cold weather to allow hot gases to pass through the seal, and to continue to allow debris to fall from the Shuttle boosters and impact the Shuttle, because they never had a Shuttle failure before, resulting in damaged heat shields on the wing.

Interestingly, though, NPR had a piece this week about the impact of cosmic rays and random bit flips that caused, among other things, a voting machine to register 4096 (2^12) extra votes and, supposedly, Toyota Prius fuel controllers to lock up into a wide-open throttle setting.

TTFN (ta ta for now)
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RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

While the instructions are out-of-order the steps presented are not.

"Electric stabilizer trim can be used to neutralize control column pitch forces before ..."

Emphasis mine. CAN is not MUST. It's an optional item of the checklist. Skipping it is also a valid (if stupid) choice, and can't be used to say they didn't complete the checklist. Turning electric trim back on can be, since that's not an optional item. But the AD did not require returning the aircraft to an in-trim state using the electric stabilizer trim switches. This is a flaw in the wording of the AD, and probably contributed to confusion.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The AD isn't a checklist...

The pilots should have been looking for clarification if the AD working was so confusing that the pilots didn't understand it. After all, a plane of the type they fly just crashed and Boeing released this AD to help clarify how to save the plane the next time. Overall, I suspect they didn't much care, at best gave it a cursory read, and carried on.

From everything I read, I believe the 2 most likely suspects for the Toyota runaway throttle were tin whiskers or physical pedal position. There was a 3rd possibility of a software routine crashing which left the cruise control stuck at its current setting, but that one wouldn't cause the sudden throttle applications everyone was going on about. Cosmic rays, not likely...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Toyota was the floor mat. The same floor mat that caused the same car to run away a few days before and was brought to a halt by a driver who shoved the brake pedal hard and pulled to the side of the road before shutting it off. He found the floor mat wedged and pulled it back; then complained to the dealer it was a loaner from. The part that was not covered in the news was the dealership was sued into oblivion for their part. Once that story was over the news had to go after Toyota to keep the story alive.

Since that one crash I don't recall any others. And, though I had searched for hours, I never saw any videos of factory floor mats interfering with the pedals of Toyotas. I expected there would be many of them if it was a fundamental problem. I would have preferred if gas pedals were hinged at the floor so that incorrect floor mats could not trap them, but those can get pushed to part throttle if any mat moves forward.

Toyota did have a throttle glitch problem from tin whiskers, but that wasn't a runaway. Instead it produced an unresponsive throttle from idle/foot-off-pedal to some engagement point at which time the computer would finally detect the position at part throttle. The jump in throttle response from the jump in detected position could startle drivers.

I don't recall any software crashes; there was an embedded applications guy who said such things could happen, but never demonstrated they actually did. He based this on his guesses/observations of how the software was developed. AFAIK no one ever confirmed any of them.

This is in contrast to the VW emmissions cheat where a guy back-engineered how the software worked to detect the car was under test conditions vs on the street. That analysis was not only repeatable, but was repeated.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

In Europe you have a button to turn off ABS.

The main reason for it is because heavy snow and ABS are not a very good idea especially with studs on.

Alot of Northern countries run white roads and runways in winter and have a compulsory change over onto winter tyres.

A normal runway condition in the north of Sweden.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

"didn't say the nominal control force was different - You went out of the way to say the Q400 has no stab trim, therefore you could never feel a stab trim problem, unlike heavy 737 pilots, who would. If you think holding a continuous 50 pounds is not a big deal when you are expecting 0 pounds, I cannot say anything about your personal ability to ignore such things, just that if I had a 50 pound sack of cement set on my outstretched arms while driving I would notice it, regardless of an engine warning light or a buzzer."

You can feel an elevator trim runway though where the trim tab hits max. Which means you have to fly the plane with full trim input. Its one of the three year exercises. And no I normally fly with finger tips. So a 50lb pull is not on all the time normal operations. The exercise in the sim usually takes about 20-30 mins to complete. I presume the reason why we have to do this is because we don't have a manual trim wheel.

Most pilots would be able to handle a straight situation like you have described.

Add in bird strike, loads of warnings and cautions going off, Stick shaker, egpws bitching your into sensory overload situation. 99.9% of pilots will never experence this in thier careers thankfully. I certainly haven't yet.

When it adds up to 3 issues at the same time, over 50% of cases it will end up in an accident instead of an incident.

Once the report is out we will discover that both crashes didn't occur as the arm chair pundits predicted. It won't change the views of some but thats also normal in these things.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Odd though, because ABS was originally designed for aircraft to handle runways exactly like that. I still see no indication that there is an option to shut it off specifically in the European market. I did see one reference that very old Audi's had a switch, suggesting that it was removed sometime between 2003 and 2005.

They must have hit an emu and it was so loud and was so startling they called for a heading instead of a pan pan. The first officer didn't mention anything about a bird strike to the tower, so why does that keep coming up? The alerts are alerts they've heard in the simulator; I would expect most stall awareness training should be on take-off and that training reflected that.

I hope the report goes deeply into how training and pilot certification failed these pilots when a report telling them how to safely fly was already released as a template for pilots getting the exact same warnings.

I will not be surprised if a report from the Ethiopian Ministry of Transport glosses over training and evaluation the way the Lion Air report failed to mention the third crew member. If there is a US NTSB report I wonder if they will be given access to the training records and scores for all the Ethiopian pilots.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I deleted my comment earlier since it seemed to be going farther off topic but the ABS can be turned off on the Tacomas and most 4x4's I'd suppose by engaging 4x4 or the E-locker. If not disabled offroad, the ABS system would be going off continuously every time you engaged the brake on soft/loose soil and possibly risking burnout I'm guessing. It's really not needed or effective offroad since the tires can effectively brake in soft soil by plowing action or friction even if the wheels are locked up since the tread is engaging the full internal shear friction capacity of the soil/snow which is the maximum resistance you can expect.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The Scandinavians hate ABS in the winter. Its not actually to improve braking its to allow you to steer while braking. As Charlie says if the road surface is low friction it creates all sorts of issues.

Here is a link to a EU commission report on the subject. I can't find any regulation on it either. I suspect that city cars won't have the option. Its certainly not the case that its mandatory to have a ABS off button. But to have any success of a model in the Scandinavian market they would need it. I suspect nobody would touch the model without the ability to kill the system. Its not a requirement for ABS to be fitted anyway for new models. Motorbikes are different they have had to be fitted with it since 2016.

https://ec.europa.eu/transport/road_safety/special...

I could see in the America market if they gave you the ability to turn it off someone would, then get killed then the OEM would get sued. So they don't let you without going in a pulling fuses.

Aircraft are different because the nose wheel is not braked plus also you have directional control via the rudder down to 50 knts ish and we have differential braking.

Its main job is to stop wheel lock up and blow out. The performance difference between normal ops and anti skid off is next to nothing. You get limitations with cross wind and runway contimination but it doesn't effect things vastly. Did 6 sectors the other week without it through the MEL. It is a B cat MEL so 3 days to fix. So is considered important but not in the same league as a DC generator or TCAS not working. If you stamp on the brakes without it all the main tyres will blow out in in a fraction of a second even at relatively low speeds. Not surprising really when you hit 16 disks with 32 360 deg brake pads with 3000 psi per wheel.

"If there is a US NTSB report I wonder if they will be given access to the training records and scores for all the Ethiopian pilots. "

There won't be a NTSB report but as they have been requested to help then they will already have all that information.

It will have the usual section on pilot experence and currency and back ground.

Training wise I suspect there will be a reasonably large section but it will center round the usage of a 45 min presentation on an Ipad being ineffective for preparing pilots to fly a MAX.

The rest of it will be likely conforms to international requirements. Which will be true, training is an issue with the regulators who have been lobbyed by airlines for years to keep the costs to a minimum. Most of it is driven by the FAA to be honest. Its dual remit of promoting aviation and aviation safety clashing. As the only method of recovering a 737 in manual trim with a heavily loaded stab was dropped from Boeing manuals in the 70's the training side of things may prove to be a twist of the knife after the insertion for Boeing.

I susepct the OEM's will be heavily hammered after this works its way through. Airlines will get slightly effected when the regualtors get thier fingers out and do their jobs. Most pilots will not see a difference.

Its a bit like after the murdering German took a plane load into the side of a mountain. everyone was up in arms after that. And if you belived the pilot haters with that one every pilot would have to undergo a full suicide check every year with the medics with a specially trained phycologist. End result 3 years later was 3 questions on the medical form about do you have suicidal thoughts.

Fundementally there is a shortage of experenced pilots. You can have thousands of low houred first officers. Captains there is a huge shortage. Its a catch 22 situation. If you flog a dead horse and force an extremely high level of training to deal with a pilot backup design then the planes won't be flying anyway because there will be nobody to drive them. Nobody will buy your product because its vastly more expensive than a type which requires less training.

If the 737 max requires 1 more sim session per year than other types then thats the type dead as a dodo. BUt I presume you will want every pilot out here to have increased training on stuff that is only relavent to the 737 max. Training is focused on the type and the operation. It would be uttley pointless for a 737 MAX driver to do the amount of gear failure training that I do. The type just doesn't require it. There is no history of issues. Q400 we do it every year and there is plenty of history with issues. Turned out though it was nothing to do with the design it was all poor maintence. But such is life. I am just glad we don't have a HUD's in our Q400's it hurts like hell when you belt your head off it when you go to the sim.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

This is the "Engineering Failures & Disasters" forum. So the focus of this thread is supposed to be on the engineering failures (hardware and software design flaws, questionable decision making) associated with the Boeing 737 Max disasters.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I would hope that the lack of realistic human interaction with an engineering system which then leads to disaster would also come under the remit.

If things are being designed for some mystical super human that has the same response at all times and the response doesn't vary individually. Then they are really not fit for use.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

(OP)
The comment wasn't pointed at any particular member. Just a friendly reminder to try to stay focused on the main topic. Auto ABS (braking control when wheels are in contact with the ground) is a subject pretty far removed from flight control system integration problems (adjustments when the aircraft is aloft).

Although... if you do want to discuss patterns you see in other kinds of software/hardware interfaces and the unintended kinds of failures that can occur, there's a meaty topic there. You're welcome to start a new topic yourself, any time you want.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

One would like to think that the final resolution of the 737 max failures would rigorously meet all defined safety standards , but the extreme financial pressure being placed on both the airlines and Boeing will ultimately imply political pressures will be applied to all of the international safety agencies to quicken the official resolution while wordlessly accepting ( ie winking at) some compromises .

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Today I happened to be checking flights for prospective trip overseas in November. I was a little surprised to see some of the equipment listed as 737Max8. This was an EU airline.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

The Canadians have kicked it out of the winter season timetable.

The winter timetable in the EU won't be finalised until end of next month.

And even then it's subject to change on the events occurring on the 31st of Oct in the UK.

There could be a huge drop in flights which will sort the hardware supply issues out. UK accounts for 25% of intra EU sector pairs.

There has been a remarkable lack of any information on recertification in Europe.

I haven't heard any date likely this year. And next summer season is not seen as definite by a huge margin.

There is a very interesting artical in the WSJ behind a paywall on the whole pilot reaction time subject.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I think 5 months should have been long enough.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

It might have been if Boeing had bit the bullet from the very beginning instead of putting max effort into blaming the pilots. But now they are into double figures number of issues which are outside certification and its basically immaterial what the pilots did. Even if the reports come out and say that the pilots did every single thing wrong, which is highly unlikely. The testing that has been done since has proved that the type should never have been released in the first place.

Now they are going for dual processing and cross check and this side of the pond anyway they are going to have to certify the whole of the flight control system to fly by wire certification standards.

And the big elephant in the room is the manual trim system. Which nobody wants to talk about because it also effects the NG.

25 months is not outside the realms of possibility now.

And even when they do get it flying again, then the next crash with any hint of control issues and that will be the type dead as a dodo.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

It was long enough for the pilots and their airlines to decide on whether to risk it.

But neither wanted to give up their paychecks did they?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Slight tangent to the thread; there must be considerable insider knowledge brewing within Boeing with regard to the future stock price. I take no direct part in the stock market, but I wonder if those "in the know" are taking any advantage, illegally, of course. I suppose any trading of Boeing or key supplier stocks by those with potential insider information will be receiving appropriate scrutiny.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

From the grounding the pilots flying them and airlines have zero input about when the plane flies again.

That's not completely true on the part of the pilots because in Europe anyway there are various pilot groups who do have an input into various aspects of the situation and what is a reasonable compromise in relation to the human interaction with the machine and sensible response times to comprehend and solve issues. But they certainly don't have the final say in the matter.

Even if they want to risk it as you put it, thankfully they can't.

And you are correct that some accountant would risk it for a gain in their bonus. If it was up to them they would continue flying it, pilot training would be reduced, we wouldn't carry alternate fuel, if the engines start you would go flying and pilots would work 14 days in a row straight with 8 hours rest a day and 200 hours in the air a month. Mind you on that last point I can think of several people on their 3 or 4th divorce who would be more than happy doing that.

But now people who are in charge of when it flies again have zero financial interest in it flying again this side of the pond. And they are also outside the political arena and pressure of the home country of manufacture.

They also now have control over the certification of the 777 program faa mutual recognition is out the window.

777x which is already late and has issues. And similar to the 737 MAX and NEO its competitor the A350 is already certified and flying.

I might add the 777 is a 1980's grandfather design up against a clean sheet 2006 design which by all accounts was pre designed for future options for ultra long haul and several other variants.

And we haven't even touched on the changes to the regulations and certification standards that will occur because of the MAX.

The fall out from the MD merger is in its end game. We shall just have to wait and see what comes out the other side. Its in nobodys interest world wide for Boeing to collapse. But it really doesn't seem as if their is anyone in the organisation who can bite the bullet and move on from the true Boeing days and design. Lets face it nothing new has come out of Boeing since the merger. Even the 787 was the product of pre merger decisions in the early 90's. All thats occured is reacting to Airbus products and hitting the market years after they have been flying after having mucked about shoe horning together something from a 1960's to 1980's tech and design.

Then they released a killer aircraft which is going to end up costing them more and taking more time than if they had clean sheeted it in the first place. But the managment and accountants will keep thier bonuses that they recived during its developement.

Lets face it modern aircraft require composites, the 777x will be boeings first composite wing spar. Its 20 odd years behind the other OEM's. The MAX is just a symptom of the cancer in Boeing and in the FAA.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Oh and to note two pilots didn't do the OEM's procedures or company procedures.

Didn't put the gear down and everyone is alive again.

https://youtu.be/XRb8bTM6RFY

On an a engineering note. This is the second time those engines have had bird strikes with small species and its ended up with dual engine failure at low level and the pilots have done completely the right thing and sacrificed the hardware to protect the contents both times not doing it as per the SOP'S.

Although to note it looks like they had one strike after V1 on the runway and then another strike shortly after rotate which took the other engine out.

I would like to hope there will be some work done on those GE engines to see if there is soomething funny going on which wasn't picked up with the bird strike testing during certification. Which from memory is a single standard bag of gelotine with some bones in it fired through a large bore air gun with the engine running at max power. Multiple small species is not tested to my knowledge.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Is it really procedure to try and land not on a hard surface with gear down??

I remember watching a program a few years ago where they deliberately crash landed a plane in Mexico by remote control with the wheels down and one thing that they found was that whilst the main gear promptly broke off as it was designed to, the nose wheel didn't and dug into the ground causing the front part of the fuselage to break off.

The main wheels though became a loose very large object and could easily puncture wings or fuselage after impact.

The profile of the 321 implies the jet actually skidded along on the engines... The right hand engine does appear to have come away at the last minute.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

yes the theory being that even if they break off it absorbs energy with its destruction.

oh to add its is recommended to try and land with the gear down preferably on a runway. These guys like sully didn't have that option. The idea that you can hang a turn just after takeoff and do a 180 and land again has been rubbished for a good 30 odd years now. Statistics show the most likely outcome is the plane stalling and crashing halfway through the turn or spinning in from low level. Picking a clear spot straight ahead usually has a more successful out come be it in a Cessna 150 or a Seneca through to an A320. There are people that do it and get away with it don't get me wrong, They are usually in extremely STOL types with amazing glide ratio, such as super cubs and the like with stupidly low stall speeds. One of my favorite tricks in a super cub was to takeoff in 15knts of wind climb and at about 750-1000ft come back to just above stall speed then we would be seen to reverse down the runway. There is zero chance I would even attempt it in say a PA38 tomahawk unless above 1000ft. The super cub 500ft wouldn't be a problem. But at the speed they fly at if your on a 2000 meter runway you don't need to turn round anyway from 500ft you just stick the flap out and land straight ahead and still have 1000 meters of runway in front of you.

It does work the 777 that crashed in Heathrow it reduced the touch down G to survivable limits. BTW that was also an initial pilot screw up flying to high when it was cold. BUt the Captain did save the day in the end by taking in drag flap which allowed the aircraft to impact in relatively clear ground before the runway instead of going into the houses outside the airport boundary.

That said the gear was up on the 777 in DXB when the pilots screwed up a go around and sank back on and everyone one survived that one as well. I suspect it more to do with angle you touch down at, than if the gear is down or not.

We don't use it on water because it will dig in and cartwheel as you describe.

To be honest in this crash I doudt very much if the gear would have been down and locked anyway with no hydralics apart from the RAT at V2 speeds even if they had selected it immediately the second engine started rolling back.

Sully went outside procedure and started the APU out of sequence to the QRH as a memory action, which gave him electrics and hydralics before the computers went off line and then would have been rebooted when the APU came back on line which would have taken vital seconds. the alpha protect mode stopped the aircraft from stalling so it touched down with minimum speed. It will be interesting to see what this Captain did and what mode the flight logic was in.

Here is a pic of the 777 at Heathrow where you can see what happend to the gear. And my mate was working in the tower when it happened as an ATCO. We still give him stick about it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

A month ago there was a rumor that Boeing would be restructured into 2 entities, military aircraft and civilian aircraft, so that the military section would survive a bancruptcy of the civilian section. As with similar bancruptcies of large corporations, the assets ( including personnel, patents and infrastructure, could then be sold to another entity, which might be a conglomerate of other investors. I do not think the civilian part would actually dissapear into the ether.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Without going too far off track the heathrow 777 was just about to touch down and very nearly made the runway. Rather different to a corn field.

that pic is my point - gear down damage could easily rupture fuel tanks or end up in the cabin. The right hand gear set detached.

It looks like there were recommendations out of that crash about what happens to the main landing gear to try and prevent fuel tank rupture, but leaving the landing gear up would be one way....

If you look at the skid marks I think the engines did most of the slow down.

Anyway on the 737 story, it does seem to have gone into a hole at the moment - Mid sept being the consensus for sending the details of the "fixes" to the FAA. Reading between the lines, It looks like it will be difficult to get re-certification / approval to fly without mandatory training in a SIM.

This is the WSJ link if you can get it for free- very illuminating, but not much on what the proposed changes are going to be.
https://www.wsj.com/articles/the-four-second-catas...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

the 777 at Heathrow didn't have any options it failed when they were in final landing configuration with the gear down. The captain managed to get the flap up to lift flap only and then seconds later they impacted.

The RAT has limited power and I doubt very much if they could have retracted the gear even if they wanted to. Retracting and extending gear vastly increases drag while the doors are open. So if they had tried they would have gone into the houses.

Anyway someone did the calcs and reckoned with out the main gear going up through the main spar it would have been over 8g touch down or some such magic number which would have meant the floor seat mounts collapsed with a 85kg adult in them. The plane did its job and everyone survived which is the main thing. They were also lucky it had been raining a lot.

I suspect details of whats required have been deemed market sensitive now and we will only find out whats happening via compnay releases to the stock market or however it works in the USA.

The FAA are only the first point of contact. Even if they say its ok doesn't mean the rest of the worlds regulators will ok it.

The interesting bit is going to be how the certification regulations are changed afterwards.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

For sure, two different scenarios so different ways of dealing with it. One had wheels down and couldn't retract, the other probably had wheels up and couldn't be sure about getting them down in time.

That 777 pretty much fell out of the sky alright but with that damage it was lucky not to catch fire. I read that it landed with 3+G so maybe it avoided the complete pancake and no time to do anything else. They got it over the A30 which wouldn't have been good to land on, but didn't quite make the runway. Anyway I get the points made.

I think you're right in terms of details of what is happening on the 737 being much more locked down than before for the planned modifications.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I think they are still arguing the toss about what has to be dealt with. And the list keeps increasing as they are discussing it.

The primary flight control system they have bitten the bullet on and basically gone flybywire.

The trim system is still and will be a bone of contention.

I have no doubt they will find other issues while certifying the new primary control system.

Then the arguments about training will start. Then there will be flip of many faces who have said it was all the pilots fault for not performing properly, they will then revert to no need for them to go to the sim they can do it all through self study at home and no need to go to the sim. Then when the next crash happens it will be back to useless incompetent pilots again.

Eastern Airways managed to smack a Jetstream 32 off the runway in Wick with 5.6g..... they had prop strikes but taxied it off the runway..... they only found out that they had split the main spar when they tried to put fuel in it and it started pissing out the wheel well.

There was a recent one in Canada with a Q400 which was over 4g and it flew for 3 days before the FDR was download and they discover it was a write off.

BTW a landing isn't deemed worthy of additional inspections until over 2.2G on the Q400. My record is 1.6G and that felt like it was a crash and we were shot down.

The 777 would have virtually no fuel in it and it was cold soaked for 9 hours and was below its wax point which was what they think might have been the issue. Jet A is a complete and utter swine to light if its cold soaked. I have spent many an hour freezing my nuts off with "trumpton" trying to get a tray of it alight so we can pull a pin out of a fire extinguisher check it works then put the tray out. Below 15 degrees you can throw flaming rags in it and it won't light. They used to have to resort to a butane torch on a rag in it in Aberdeen training centre for 10 mins before it would light up. Working in the middle east with air temps above 35 degrees whole different ball game. Its normally heated by a oil cooler to heat it before it goes into the engine to be burnt and any excess returned to the tank to try and keep the temp up of the rest of it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Is this the article you linked, Alistair?
Same authors.
Same first paragraph.
No Pay wall.
https://www.msn.com/en-us/money/companies/the-4-se...

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Alistair, at least we agree that the pilots did risk the lives of their passenger for the paycheck. There is no evidence they bothered to understand either the AD or the Ethiopian Airlines specific FCOM pages. Also, it may surprise you, accountants don't make decisions about how to run companies. The management does. And the management of Ethiopian Airlines was perfectly happy to take the cash saved by not training their pilots in exchange for the deaths of all those passengers and the crew.

How does a cancer filled company do a successful clean sheet design? Seems like the only other choice was to liquidate the company when it was clear they were diseased people running it instead of building on what worked.

That article - where is the 4 second reaction time requirement spelled out? I see the claim, just nothing to back it. I know that Ethiopian Airline had been given all the info about MCAS that is repeatedly claimed was withheld. It should have been in the manual, but maybe Ethiopian Airline management expected a big payout from a crash? What other motive could ETH have for not passing it to pilots? Or did pilots round bin it as just another piece of junk mail?

Seems like another hit piece as it leaves out every misstep the crew made to ensure the crash happened.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Re. 777 Heathrow "BTW that was also an initial pilot screw up flying too high when it was cold."

I trust that was intended to be gentle sarcasm. Famously, it was the fuel heat exchangers that were redesigned. Tubes a bit too long, preventing the ice from contacting the hot plate.

Report: "G-YMMM was operated within the certified operational envelope at all times."

Edit:

Please take note of the above quotation that is from the report. This contradicts any claim that the pilots were outside the approved operating conditions.

Also, the fuel heat heat exchangers did not perform their basic function. They failed to melt particles of ice, and in fact became clogged with ice. They were not redesigned because they "didn't help"; they were redesigned because they didn't work, and were a menace.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

There is no evidence that they didn't read the AD. I know for a fact compliance with a written instruction bares very little resemblance to the first attempt of a new procedure in the sim. A bit of paper or 45 min ipad presentation is just not going to cut the mustard for a new critical failure.

The First hole of the cheese was Boeing management cutting corners and pushing through a flawed aircraft because the competition had a flying product released already and they were loosing market share.

The engineers who gave into management pressure to keep their pay checks were the next slice.

The certifiers the next slice etc etc.

The at the very end airline and crew.

Then we ended up with two fatal crashes.

Nobody is going to say the pilots or airlines were blameless in either crash. But all that was required was one hole to be closed in the other multiple slices and two crashes would never have happened.

The heat exchangers did get redesigned after that, but above the tropopause was unusually cold that day below -70 and lower altitude and every other aircraft had descended into warmer air because the fuel was getting too cold on multiple different types. I suspect they were a bit tight on fuel and didn't want to descend. They didn't get any cold fuel ecam messages but the fuel was in minus figures already in China when it was loaded. And to be honest I really wouldn't trust the fuel in china to be of the same quality aka water content as the fuel in Europe, same as when I load it in Africa and a few other places. I carry my own water test kits when I work in those sort of places and have refused a fuel load more than a few times because of water content. Its not mandatory to do this test as a pilot in theory the fuel cert and company QA should ensure its OK, its just my own self preservation SOP.

They had been planned to descend by ops but elected to monitor instead of complying. But it was decided that the design didn't help things so they fixed it. I Think they also did a fair bit of work on if the fuel temp sensor was in the right place and gave a true reading. And I think there was also something about one tank had two hydraulic coolers in it and the other one only had one but as both engines failed I doubt that made any difference. So its not a clear cut engineering issue. We will never know if they followed the flight plan if it would never have happened.

The 4 second thing seems to be a FAA certification standard we can't find it in any EU regs. There seems to be a lot of noise about it your side of the pond along with some of the other reaction time stuff. Must admit it did make me laugh the first time I saw someone state that if its your average American airline pilot can react in 4 seconds and save the aircraft with Boeings design, that means there is 50% of them out there that wouldn't save the aircraft, how about sex and travel Boeing.

Must admit some of the numbers coming up with predicted reaction times are highly dubious from my own experience. 10 seconds from rapid decompression to hitting 5000ft per min in the decent. After 10 seconds you would have only just got the mask over your head and established coms but not yet finished farting. BTW the A220 has a button you press then it will take you down to 10k or MSA which ever is higher while your putting your mask on.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

4
3DDave,

I think personally you're going too far here in the desire to blame the pilots.

One thing that always reassures me when I step on board any aircraft is that the person(s) at the front of the bus have an equal desire to arrive in one piece as I do (barring the odd suicidal lunatic).

So to say that they in essence "engineered" the crash is going way too far.

And in essence all pilots take the paycheck and take the risk. I think if most of us knew how many faults were present on aircraft that were still deemed fit to fly then we wouldn't set foot inside them. Is that risking the lives of passengers for a paycheck?? Happens every day. But the airlines would argue those risks are managed and evaluated.

Now there may well be faults in how the AD was transmitted to the pilots, though clearly not helped by the lack of the AOA disagree alarm on those planes, something Boeing knew about but did nothing, and the strange way the AD was written. It's basic tenant which was turn off the electric trim, don't worry you can always manual trim, has been proven to be false. Also it is clear from the article and from our resident pilot here that the runaway trim issue did not occur in isolation and can severely overload the pilots ability to determine what the correct actions are when all sorts of alarms and things are happening with NO SPECIFIC ALARM.

It is clear that there was an overriding aim from Boeing during the design and certification process to avoid requiring retraining of pilots to save their customers money. A noble aim no doubt, but in this case may have gone too far. As numerous articles state, the basic boeing philosophy is to grant the pilot the ultimate control. Hence why normally pulling the control stick back cuts out the automated trim movement. But now it didn't due to the fact MCAS needed to operate in those conditions and they essentially found themselves in a strange place between "manual" flying and FBW.

That the manual backup system now didn't work due to size of the stabiliser increasing and the diameter of the wheel going down, plus a rather fast aircraft is not down to pilot error. That's a design fault. How they fix that will not be a software issue I fear and may be a key issue that is very difficult to solve.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I wouldn't worry about blaming the pilots to much they do carry a portion of the blame. It's pretty much sop anyway. And if that doesn't work next stop is maintenance.

You get pretty hardened to it after a couple of years working. It's half the skill of being a Captain is covering your arse against the obvious lines when the finger pointing starts. Mostly it's ops issues such as pax offloading and refusing cargo. The flying is easy in comparison.

You will never change the view of pilot haters anyway.

Let's face it our one's comments has triggered the complete re certification of the autopilot disconnect system. Must be 30 odd people and 2 months work and add in the flight test flights plus mods. An easy 10 million I suspect. Mods installation are extra.

They will never acknowledge what the true environment was like when the mcas triggered the three times.like our partners they just think of pilots sitting on there arses drinking tea for a 12 hour shift. Never been on a jumpseat ride in there lives in shite wx.

Btw I am sitting on a beach after having a brake failure this morning....

And I didn't follow the qrh I learned afterwards. No memory items in the qrh for the failure. A read and do checklist for a antiskid caution in the air which doesn't cover it anyway.

You have to love turbo props. Touch down get it into beta touch the brakes and the master caution goes off and the aircraft heads off towards the side of the runway doing 100 knts. Release the brakes slap in 6000 shp full reverse as you give it full oppersite rudder yell your tops and go for the tiller... Start thinking about the emergency hand brake. Sod it we are at 50 knts now. In theory I should cancel reverse now... Sod that I will tell the technicians I busted it. Get a remote stand so didn't need a tug.

Write up in tech log mention about using rev below 50 get laughed at by technicians. Do I know how long it takes to do a runway excursions inspection? Go home after a 12 hour shift finishing at 6am to be met by my 4 year old boy who has a broken favourite toy. Soldering iron out and fix it. Go to bed after being awake for 24 hours at 8am. 2pm awake and go to beach and sit down with a beer and write a reply on this thread.

To be honest I don't even consider this an unusual day apart from I can have a beer because I am off tomorrow after 6 days working. I get 36 hours off then back for another 4 sector day starting with the alarm clock going off at 5 am for another 6 day block. Oh and I got my leave refused next month because of lack of captains.

Now should the OEMs design for the average well rested pilot. Or for the minimum skilled pilot who has been working 10 hour shifts for the last 6 days?.

I would like to think I am not anywhere near the minimum skilled label. But the state of my underpants after this mornings adrenaline burst could have been done without. Don't worry they weren't brown just a bit damp with sweat and the seat cover needed extracted after I cancelled reverse.

To be honest sorting out a surface mounted usb port was quite therapeutic before going to sleep.

Now I think a second pint is in order.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Hmmm,

Sounds like an interesting landing...
Why the 50 knots limit? I've been in turbo props that have reversed to get maximum take off length in the past.

The flight crew working times do seem high sometimes and it has turned up a few times on ACI. how you factor for that in a design environment is an interesting thought - double reaction time?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Mate just read your edit I utterly love I am blaming the command choices and you are blaming the engineering.

That's the way the system should work for ensuring safety. No finger pointing at others. If everyone says it's our fault we will work to minimise the chances of it ever happening again. Your risk is decreased by multiple factors.

The utter pish of finger pointing and trying to target one specific group as the culprates will have no where near the same benefits.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

50 knts is because of the composite props and recirculation of crap off the ground basically eating them. Its to try and limit delamination. They are a 1/4 mil each I think for the q.

If you are sliding towards a follow me car at 10 knts you use it. You just tell the techs and within 10 flights they run a ultra sound over them and see if they have delaminated apparently.

A normal landing for me with a 28 ton q and 2000 meters of black I don't need brakes or reverse.

The q400 is stupidly over powered. I have never done a mtop take off ever evenin the SIM.

The Jetstream with dowry or Macaulay props made out of metal there was zero limitations. We used to reverse off stand. Had a complete brake failure including emergency brakes due shuttle valve jamming going into Plymouth UK which is 1600 meters in a Jetstream which has a school 300 meters off the end of the runway with a 100 ft drop. I hit full reverse and by the time I had sorted my shit outin my head after 1000 meters of runway used we were reversing back up the runway. It was pure overload I hadn't cancelled it. The ground handlers all thought I was showing off.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Makes sense.

BTW I'm a London based pipeline engineer, (If you click on a persons handle they sometimes have extra information on their profile and somewhere you can hover over and it lets you know their location) but I follow these sorts of threads to broaden my knowledge of things. My family only let me watch ACI when they're out...

Been on a few hairy flights to Sumburgh in my time and used to love jumping out of aircraft for fun, mainly turbo props with the odd piston and the very occasional jet or ballon or chopper. I fly a fair bit on business so am always interested in why some of the buggers fall out of the sky, always hoping it never happens to me. I do carry a smoke hood with me now on flights - seen too many disasters where people died because they couldn't see/ breathe. Gets the odd strange look at security, but no ones stopped me yet. Whether it would work god only knows but it makes me feel safer.

enjoy your beer.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

I used to fly for Highland airways into sum delivering the Sunday sport in truely shite wx.

When I was doing my failed PhD my supervisor was Donald Mackenzie at Strathclyde and Tommy Grey.

Born in ABZ and dad a radiation protection advisor

Saw my first industrial fatality in an oil yard in ABZ when I was 15 years old. I went under the lorry Axel's and the other guy tried to run away. He got splatted I shat my pants...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

btw I personally think these sort of threads are useful for all flavours of engineers.

If my comments make you think even once about how the operators can f up and abuse your design and you protect against it then. I will be an extremely happy ex fea nonlinear now captain ex practicing engineer.

Although I have just installed a dogs bollocks heatpump heating and cooling system in my farm and thanks to my engineering skills I have avoided having an extremely crap system installed. Also just put through the drawings to a roof truss manufacturer for frames for the barn with two tons of solar panels on the roof.

And apparently I talk sense to the spanner monkeys. So the qualifications are not wasted. Still have a copy of ansys on the computer and k-pipe. I recon I could still write 90% of an ansys input deck without ever booting it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

Boeing shares rise as company hires for 737 MAX work

Boeing announced plans to hire hundreds of temporary workers to help roll out the 737 Max aircraft once it is FAA approved, which is likely to happen before Thanksgiving.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

(OP)
THIS THREAD IS CLOSED.

Please continue the discussion at the new thread:
thread815-457125: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Thank you everyone for this enjoyable discussion.
This topic is being broken into multiple threads due to the length to be scrolled and many images to load, creating long load times for some users and devices.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

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