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Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]14

Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

(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]
thread815-454283: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4]

This topic is broken into multiple threads due to the length to be scrolled, and 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.

Some key references:
Ethiopian CAA preliminary report

Indonesian National Transportation Safety Committee preliminary report

A Boeing 737 Technical Site

Washington Post: When Will Boeing 737 Max Fly Again and More Questions

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 5]

2
(OP)
Last week I spent some time in the Seattle area, touring the Boeing factory, aviation museum etc. It put me in the area to take this picture. It may LOOK like a picture of some 40 airplanes, but it's actually a picture of FOUR BILLION DOLLARS:

Somewhat larger version of the photo at this link.

This is not to minimize the tragic effect that the accidents have had on the victims and their families. If anything, this photo reinforces to me the principle that our western society upholds the safety of people from around the world, and that there is a light on the things we do and the ways we do them. If we were allowed to do our work in secret, we would never learn from our mistakes. If we offered nothing but arbitrary punishment for such fatal mistakes, there would never be risks taken such as the design and development of technological marvels such as intercontinental aircraft. That would leave the regions of the world more isolated from each other.

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 5]

Would love to do that tour.

I have managed to avoid visiting Toulose so far for an ATR rating, but spent quiet a bit of time flying the corporate bus service out of Filton on the J41. The wing production and transport of them was most impressive. The Beluga is a sight to be seen in real life, its way stranger than the pictures.

There is still nothing new from the EASA side of things apart from alot of personal sceptisism about the projected time line by Boeing. Alot think that it might get recerified for USA only airspace. A mention of China airspace just produces laughs.

And nobody can see Boeing being able to recruit enough short term contract A&P technicians with the current recruitment to be able to sort things out quickly. I presume alot of the aircraft won't have their final paper work completed so the won't have to use licensed technicians whichh will help.
And it also seems for FAA pilots the 1 million per airframe hit has won the day over safety.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Seattle area is a great place to tour aviation technology related to Boeing, and other mfr's technology as well. I recall a presentation at the monthly ASME meeting in 2001 of the Boeing efforts to maintain a small fleet of ME 262 german jets,which were recovered at the end of WW2 and kept in working order at the Everett airfield. That meeting was packed to standing room only , as the presenter described the recovery efforts and the ways such older fighter jets are modified to permit modern use.

The first few years of their use in the USA retained the original machine guns, as a required weight balance issue, but when the FAA finally inspected them in '49, the inspector said that civilian jets may not fly with mahcine guns, so off went the guns and on went some other form of ballast. The oringinal jet engines were replaced with the same type of jet engines used by cruise missiles in the 80's ( these same engines are also used by small helicopters). Apparently some millionaires have contracted to have Boeing engioneers ( in their spare time) build replicas of the ME 262 , coming to an airfield near you.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I've done the Everett tour and aviation museum, and it is excellent.

It's one of the few tours I've done where you're in close proximity to and have an excellent view of what's actually being made (unlike, for example, the Miller-Coors tour in Golden, CO where you're behind glass listening to prerecorded stuff the whole time).

The museum also has an excellent collection of cool aircraft. Highlights for me were the A-12 and one of the first 747s.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

How Miller and Coors is brewed... must have been riveting

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I doubt it - to be honest, riveting's more likely to have been how the 747 was made. oblig

A.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Nice one![lol]

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

(OP)
Well since we're talking factory tours...

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 5]

I heard that part of the proposed fixes to the 737 Max is to operate both FC computers simultaneously , and if they disagree with each other , immediately disable both of them and engage manual flight control. It would seem that this strategy would generate additional risks if the FCC disengaged during a landing.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Most landings are manually flown anyway.

If they are doing a reduced minima approach cat 2 or cat 3 there are already procedures to deal with automation failures during the approach.

What the worry is if they then have to go-around and they have no protection against the dodgy stability that MCAS was put in for. And the approach and takeoff phases are the high risk area to get bird strikes which is what happened in one of the crashes and it took out one of the AoA sensors.

The risk will be quantified and if its deemed too high then the aircraft won't get re certified again without them mitigating the risk.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Apparently this isn't the first time the FAA has been seen to be deficient in their safety role. Link

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Apparently its the rest of the world regulators who have caused the latest delay.

A meeting last month was cut short by them and Boeing told that their documentation was insufficient on the dual FCC setup. So they have to re submit.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

(OP)
You can point fingers if you like, but it's hard to give Boeing much credit. The standard they failed to meet was the required standard decades ago, and Boeing has supposedly been applying the standard all this time. If trust is lost, then it has to be gained back with more rigorous proof.
And it makes the FAA look bad, too. No surprise they want to check every box, cross every tee, dot every i.

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 5]

I don't think it was even more rigorous proof than normal. There was apparently pretty much zero technical details on what they had done to pair up the FCC's and when verbally asked about the setup they failed to give a coherent reply. And they claim it doesn't have to meet FBW certification standards.

Apparently the FAA was quiet happy to sign it off, EASA started asking questions, management waffle commenced. Once it was finished the meeeting was cut short by the other regulators.

Patrick Ky (EASA) has stated that EASA will be certifying parts of the flight control system independantly to the FAA to the EU transport committee.

"The agency has come up with four conditions that have to be met before the MAX can fly again in Europe. Primarily, all modifications must be approved by EASA itself. Additionally, EASA demanded a “broader review of the design of safety critical systems” of the MAX which had previously been performed by the FAA. “That was not very popular with our American colleagues,” Ky hinted. EASA also wants a “complete understanding” of the Lion Air and Ethiopian Airlines accidents both from a technical and operational point-of-view. Finally, the agency wants to ensure that flight crews are adequately trained."

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I suspect the big problem the FAA has with EASA doing a review is they know fine that there will be a multitude of other issues appear outside certification.

More than a few will show that they haven't been doing their job properly for decades.

I am sticking with my prediction that it won't be flying outside the USA by next summer season.

Although quiet how the US pax will feel about flying on an aircraft that the rest of the world won't fly on I really don't know, if the FAA decides to certify while the others don't. Then we will be into the situation which was a complete pain in the backside when I started out that you had different models and certification per area of operation.

And the 777x certification timeline is pretty much a work of fiction now.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I can't help thinking that with the billions lost so far, Boeing could have solved the problem of low ground clearance and found a way to extend the landing gear and relocate the engines under the wings, ten times over.
Rather than address the problem they are apparently still trying to mitigate the symptoms of the problem.
After many years of experience trouble shooting I can't count the number of times that I have seen that approach fail.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

waross,

We've looked at that many times - they would need quite a lot more undercarriage clearance hence total re design of the wing root

Also the other big issue is simply the size of the stabilisers compared to the elevators and also that there is now only one jack screw instead of other systems wholly manually controlled / driven to control their angle.

These issues also exist with the 737NG, but they didn't have a potential mad system moving them Nose down.

But yes, it seems they have no choice other than to address the symptoms or scrap all the existing 737 max aircraft.

We all know the FAA is going to under pressure to get the 737 max flying again and their dual role puts them in conflict.

I don't doubt for one second that there are differences in opinion between the different regulators and that the FAA has lost the respect of the other parties and there may be a power play going on here.

I went trawling yesterday and this dual FCC comparison story surfaced in early August which implies it is a bit of a last minute design to try and resolve the structural design issues. It doesn't sound like the best plan to me, but I can see the point - if either FCC goes haywire, shut both down and hand the controls to the pilot. Not sure it will stand the scrutiny of the regulators though.....

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 5]

Quote (waross)

Boeing could have solved the problem of low ground clearance and found a way to extend the landing gear and relocate the engines under the wings,

I don't see how the landing gear and engine relocation under the wing is related or helpful. This would increase the problem created by the larger Leap engines. Lowering the center of thrust with respect to the center of mass, either by increasing the engine diameter or lowering position of the engine, will increase the nose up tendency and increase the need for MCAS input and the amount of hard built-in trim (decreasing efficiency).

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

The issue with the Max is mainly due to the fact that the engine nacelles themselves start to generate lift at high angles of attack.

When you look at the two engines between say a 737 and a A320 the actual centerline isn't that far away.

The 737 engine looks like even now it had some help from the manufacturer to move some components to the top to minimize the height.

The AA320 with a similar engine is much rounder.

737 max

A320 neo

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 5]

Any substantive re-design is going to cost many additional billions, AND possibly a year or more in time delay.

Of course, EASA wouldn't have ANY parochial tendencies to given Boeing a few digs in favor of Airbus ...

TTFN (ta ta for now)
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RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

The same effect is more than likely present on the neo as well.

But as there is no control force feed back to the stick its not an issue under fbw certification. For you to lose alpha floor protection you need to go down to the third level of failure mode and even then your not into direct pilot control. There is another level below that.

The problem with the max is that anything goes wrong and the first failure level is the pilot and no protection and control forces changes which are the reverse of any other commercial aircraft and the max when it's working properly.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

EASA really aren't being difficult due to Airbus. They are pain in the ass bureaucrats to everyone that has any thing to do with them.

Airbus's production lines are full anyway. They seem to have some good product lines which the customers want. Boeing hasn't produced anything new since the 787 came out in 2007 which also had issues with its battery's and it appears to have absolutely nothing in the pipeline. It makes zero difference if the 737 max is flying or not to Airbus for the next 10-15 years. It will have a good effect on powerplant availability for the NEO production line but it won't create any more revenue if the MAX is grounded.

Giving digs to the FAA I could see. But Airbus V Boeing I can't see.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

787 has about 650 unfilled orders at 10/month that's five years of orders. Not sure why you think that's nothing in the pipeline. It's about the same number of orders as Airbus has for the 350. If you want to talk failures, the A380 should be at the top of that list. Only 321 are expected to be delivered before ending production.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I think he means new designs of airplanes... 797 anyone?

https://simpleflying.com/boeing-797-update/

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 5]

There is nothing new.

It's all grandfather types. And all reaction s to other OEM, brand spanking new clean sheet types.

The nma is 15 years too late.

They haven't even officially started on it.

Boeing still hasn't got a composite spar. Emb, DH and AB have been making them for years.

757/767 is getting well pumped. Btw the 757 with rollers on is one of the few that gets my juices flowing.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Huh? Boeing doesnt have a composite spar?

Ah, there are composite spars on the 777 empennage, on the 787 wing and empennage, and on the 777X wing and empennage. I worked on the 777 emp ones staring in 1989.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

It has bits of them I agree.

I think the wing is 50% composite 20% Al 10% steel and 15% titanium on the 787. Can't remember what material the rest of it comes under.

I was meaning the main wings spars. And wing structure

Boeing only got the big autoclave in 2015 for the 777x wings.

The big one went into Hawarden in the 1990's I think.

OH and I completely agree about the A380 slug. Huge mistake by AB management. But the silver lining is that they learned alot from the mistake from an Engineering and production POV and targeting a product. They did it to try and take on the 747 when the airline industry was moving away from 4 holers for pax transport. Since then they have been focusing on aircraft that are actually useful and have a much broader market. I am no lover of Airbus products BTW to work in. But I do admit when travelling in an A380 it is an extremely nice aircraft for long haul much more pleasant than a 747-800.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Boeing is working on the NMA, but in hindsight it might have been better to be focusing on the Y1 first instead of putting all their narrowbody eggs into the MAX.

I don't particularly see Boeing as being a non-developer. I also don't see Boeing as flogging old designs any worse than Airbus does. Airbus just doesn't have as old designs to flog. Both Airbus and Boeing currently seem to be capable of bringing a new design to market about every 10-15 years.

Boeing had originally planned to develop the Y1 to be entering the market at about this time. But, they switched to developing the MAX instead and pushed off the Y1 at least another decade. In hindsight, that was a terrible decision. It also seems odd to continue pushing off any 737 replacement development considering the insatiable demand for that aircraft type.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

From https://simpleflying.com/easa-737-max-test/

"EASA wants Boeing to demonstrate the stability of the MAX during unusual and extreme maneuvers, both with the updated MCAS in operation and with the system switched off." (emphasis mine).

It is my understanding that MCAS is required for stability in certain (extreme) parts of the flight envelope, due to the positioning of the engines. Doesn't that make this test impossible for the MAX to pass?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Maybe their intent is to ensure that the system no longer fights the pilot/reactivates itself once it's been disabled and not ensure the MAX can perform those maneuvers without assistance?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Here is the original presentation slides.

To be honest although everyone focuses on the MCAS side of things.

The trim system is going to be the hardest one to deal with.

https://www.europarl.europa.eu/cmsdata/186500/2019...

MCAS alters the control forces that the pilot feels as they approach the stall. Normally the nearer you get to the critical angle of attack the more force is required on the controls to increase the angle of attack.

Because of the engine position and the lift generated by the bottom of it, this produces a moment which means the force to increase the angle of attack is reduced the nearer you get to the critical angle of attack.

It won't be Boeing doing these test flights it will be EASA test pilots and engineers.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Hmmmm. The manual trim wheel forces one is going to be interesting. Nothing there about this check of one FCC against the other.

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 5]

" Extensive change to the Flight Control Computer architecture and logics (incl. Autopilot
)"

On slide 15, I presume is the dual channel FCC and changes to the relays.

Although the bottom one about no approprate changes to the integrety of the AoA system sort of knocks it on its head.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Just a link to the tech pilot 737 max legal issues.

The next one is just out of interest. they were doing the 777X wing loading final check and a door blew out. Which would have a been a scary big bang if the fuselage was at max differential pressure.

nice pic of the internals of the new 777x wing though.

To be honest its a pretty poor article. Nobody seems to know if it was a plug door that went or won't of the cargo doors.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Quote (Eufalconimorph)

"EASA wants Boeing to demonstrate the stability of the MAX during unusual and extreme maneuvers, both with the updated MCAS in operation and with the system switched off." (emphasis mine).

It is my understanding that MCAS is required for stability in certain (extreme) parts of the flight envelope, due to the positioning of the engines. Doesn't that make this test impossible for the MAX to pass?
I wouldn't quite jump to that extreme. MACS off means that some low probability failure has likely occured, different requirements apply.

In extreme parts of the envelope with MACS off you could have anything between "ooh this makes handling a little bit more challenging but nothing too hard for a pilot who expects it..." to "OMG this is next to uncontrollable and can readily lead to unrecoverable positions".

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

That's the thing though MCAS being off is not deemed low probability. For that it needs to be 1 in 1 million flight hours or flights depending what code your looking at.

The logic is that with the dual FCC then mcas will be off whenever they spot a mismatch with the AoA sensors. That happened twice in under a year.

And the high alphas with manual flight occur when ever there is a terrain avoidance, wind shear and to a lesser extent during a go-around.

I have been trying to think of an example of the effect which none pilots can relate to with this effect.

The only thing I can think of is the brakes on a car. With a normal car the brake force required by the drivers leg increases the nearer you get to brake lock up. If the car was the same as the boeing MAX the brake force would increase up to 90% wheel lock up and then would decrease over the final 10% of travel. So during an emergency stop the driver would have to remember to reduce the pressure towards the end of travel to get best performance. And if they do lock up the brake force would increase as they backed off the pedal. All while trying to stop before hitting a child or hitting a wall or other vehicle. Most of the time you wouldn't feel or experence the effect. The MCAS when its working has a ABS effect of pushing back on the brake pedal increasing the force felt by the drivers leg the nearer you get to lock up. It would be like in a car and the ABS system failed instead of pushing back on your foot then it would change to the brake force on the pedal suddenly decreasing and the travel increasing suddenly when the wheels were about to locked up.

Humans are relatively good at dealing with linear force changes giving a linear effect. We even convert stuff and use cams to give logrithmic changes to controls to give a linear responce for a linear change to the control. Evolution just hasn't set our sensory and motor skills up to deal with with nonlinear feed back and control input. We can sort of do it with lots of brain capacity used. But if your relying on the baser parts of your brain to sort things out which use muscle memory and learned reflexes its a completely different story we generally fail to give the correct responce even with relatively low stimulus loads.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I am thinking about driving a car in a large, icy parking lot. You keep turning tighter and tighter. As you turn tighter in the old, pre-power steering car, the force to turn the steering wheel increases. Then the front wheels loose traction.
Two things may happen, The car ceases to turn and goes ballistic, and the steering wheel forces become very light.

As I understand the combined action of the uplift and force couple, You loose the feel of the stick, and without moving the stick, the plane may continue to increase the AoA.
I seem to remember one account from testing that indicated that when the stick went "light" the pilot had to, counter-intuitively, push the stick ahead to avoid a stall.
Asking, not telling, but when the stick feel "goes light" are you at, or dangerously close to a point where the AoA will continue to increase into a full stall unless the stick is pushed ahead?

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

It won't increase without pilot input. If it did then it would be unstable and even with MCAS it would not be certifiable. As you get nearer the stall the force required to move the stick back to get closer to the critical angle of attack needs to increase the nearer you get to the critical angle. WIth the max with MCAS off the force does this up to a certain point until the engines start creating significant lift. Then it decreases the closer you get. With MCAS turned on when the engines start producing lift it trims the stab to create more force on the stick so it continues to behave normally like all other none FBW aircraft that the pilot has ever flown in the past.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Just a slight tangent to Alistairs post about car brakes, many probably know this, but traditional automotive drum brakes are designed to be servo-actuated, or self energizing. I.e., the torque applied by the drum to one of the shoes due to intentional geometry, increases the normal force of both shoes to the drum. The geometry is typically such that the self-energizing component of the force is a fraction of the force applied by the cylinder, but is nevertheless significant. This lead to non-linear behaviour as Alistair described. The main outcome, due to the open loop system, was uneven and time variant braking at each corner, hence a tendency to weave under hard braking, which required correctional steering input by the driver to follow his intended path. Obviously not a recipe for minimum stopping distance. Despite this, some all drum brake vehicles back in the day turned in quite creditable controlled braking distances to a stop from 60mph, the humble VW beetle being one. I believe full sized Buicks weren't bad either, after they had introduced their finned aluminum drum design. This after being lambasted on braking performance in Ralph Nader's book, Unsafe at any Speed. /tangent

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Ford pioneered the self energizing brakes.
Dodge and GM were years behind.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I was only trying to think of an example that people could relate too about having a control which gave none linear responce to linear input that was universal across all flavours of engineering.

The old plant had some nonlinear responces to hydralic inputs mainly due to variations in circular orifice as you opened up a control. But I discounted that example as I presume it will only be a select few who have had to sweat htough that learning curve.

I might add that all the digger operators that I taught to fly the manual manipulation skills were "taught" in seconds. NAviagtion though was a bit more of a challange for them.

I might add I hired a small tracked digger last month to shift some crap on the farm. I was quiet surprised how quickly it all came back, like riding a bike. Must have been 20 odd years since I had to operate one. Changed quiet a bit since then all the controls are linear response and rate of movement is linear. No more slowly slowly movement with deflection of the stick then a ball hair more stick and the arm triples in movement rate.

Most youngsters these days will have never had to get to grips with nonlinear controls. And if Boeing get their way they are meant to be able to deal with them in 3 seconds response time after reading about them on a Ipad with loads of alarms going off. And if they screw it up the electric trim is gone thanks to the new dual FCC killing the trim system if it spots a mismatch and the speed goes up by 50 knots they haven't got the strength to turn the wheel with out doing a rollercoaster manoeuvre.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

(OP)

Quote (waross)

Asking, not telling, but when the stick feel "goes light" are you at, or dangerously close to a point where the AoA will continue to increase into a full stall unless the stick is pushed ahead?

Speculating, not knowing, I will offer this opinion, based on a curve that circulated on the internet several months ago. It looks plausible, but the source is not confirmed to be valid, therefore this is NOT factual. Just some ideas, related to this question:

This curve represents a pitching moment curve, which is the moment that is counteracted by the tail. The moment must be counteracted by an opposing force at the tail for the aircraft to maintain any constant angle of attack. Trimming the tail changes the angle of the tailplane, which forces the aircraft to assume a different "trimmed" angle of attack. Usually this is done in very slight increments, not the exaggerated change in the graph above.

The graph shows several different pitching moment curves, intended to illustrate someone's attempt to explain how MCAS works.
1) the blue dashed line represents the preferred pitching curve which is linear and consistent through most of the flight envelope,
2) The blue solid line represents the pitching curve that may have resulted from the 737 max engine configuration change,
3) The green solid line represents the 737 max pitching curve after it shifts with a change in tailplane trim pitch,
4) The green dashed line represents the transition from one pitching curve to another as the MCAS operates to add some tailplane pitch.

So the graph seems to have some exaggerations, but it's useful to show how the system might be functioning. A few adjustments to the rate of MCAS pitch changes would allow the green dashed line to follow the blue dashed line more closely. As it is, I believe the graph is just printed the way it is for illustration and clarity, not to correspond to any actual data points. Another possible consequence of this kind of pitching behaviour could be that the control forces get lighter at higher angles of attack; another thing that corresponds to the reports we are hearing.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Thank you Steven.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Just asking a quick question - From what I understand the two FCCs on the 737 operates on a working / standby or side to side configuration?
Would switching the FCC from the side going nuts (in both cases the captains side) have made any difference?

Either way I can't see how these apparently proposed AOA or FCC disagree functions is going to work if the answer is turn them off / disregard the signals. Also by how much can they disagree and still be OK? From the graph above it looks like only a few degrees. How accurate are these things?

Fundamentally the 737 max has flying characteristics which means MCAS is required to meet the certification rules of constantly increasing stick force vs AOA. No MCAS or FCC then it just opens up another hole in the swiss cheese.

The other aspect is the size of the stabiliser vs the force from the manual wheel means it can't realistically be used as the back up once the speed goes up a bit. So this would need an additional actuator or a whole new set of standalone "manual" wiring to the jack screw.

Hence two massive issues to try and resolve without either making large mods to the several hundred aircraft already out there and / or needing the pilots to all train and re-certify for this variant of the 737.

Kind of tells the reason why it hasn't happened yet I feel.

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 5]

I suspect that the best technical fix is to use 4 AOA devices, but if Boeing agrees to this , then it implies the use of one active AOA was "negligent", which is the legal N word that no company wishes to have to respond to in court.It may also occur that the investigation of Boeing actions that effectively muted engineers' cautions and prohibitions re: use of a single AOP constituted a conscious effort to accelerate the deployment of the aircraft then the N word could again be used in court. If a judge deems the N word is valid, then there is no financial limit to the damage awards, and it would spell the end of Boeing.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

On the one hand there are a lot of jobs and a lot of loyalty towards Boeing.
On the other hand, there may be a limit to the physical size of engines relative to the physical size of an aircraft.
That limit may have been passed with the Max.
Looking forward to future designs, not as a fix to the Max:
Larger fans yield greater efficiency.
Big engines are not going away.
But when we look at the cutaway of a leap engine without the bypass ducting, it is quite narrow waisted.
Is it feasible that future engines will be mounted much closer to the center of lift with part of the bypass ducting passing over or through the wing?

Quote (Dave)

and it would spell the end of Boeing.
Does anyone remember Konica and their one bad design choice?

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Quote (Bill)

Does anyone remember Konica and their one bad design choice?

I remember old Koni stuff I used to have a Koni C35 AF, the first production autofocus camera. When you pressed the release, the lens would move from the infinity position to the near limit. When the rangefinder images matched, it would stop the lens and release the shutter. The guy who shot some of my wedding pics used a Koni Omega 6x7

At the george eastman house you can see the a prototype, the first working digital camera, made by Kodak. They were famous for something else though, but it escapes me...., printers maybe?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Regarding powerplant size, there was a step change when turbojets overtook piston engines, not to mention turboprops, as the powerplant of choice for large airliners. If you take axial cross section for powerplant size, then this was an enormous reduction, and since then size as a function of thrust has been steadily increasing. Yet we're far from being all the way back to pure propellers as far as specific size goes (nor even absolute size), and I doubt we ever will get there. I don't rule out open props again on the largest airliners in the long run, but I suspect in that case that thrust as a function of disk area will be much higher than the previous norm.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

A report is due out on the process. f you do the private window opening and hit stop in the browser you can read it without having a subscription.

https://www.wsj.com/articles/international-panel-s...

" How accurate are these things?"

Normal range is -20 to 20 deg and 1 decimal place output to the FDR. Normal operating range is 3 deg to 16 deg.

If they had worked out it was FCC problme they can switch them, you can switch ADC's and AHARS as well. BUt you can't switch the sensors. The big problem is working out which one is giving duff info. The primary airdata you use the independant standby horizon instrument as the reference.

"Is it feasible that future engines will be mounted much closer to the center of lift with part of the bypass ducting passing over or through the wing?"

Already been done see the design of the comet. Having the engines in pods where if they fail they don't take out the fuel tanks is one factor, second is hot gas inside the wing is not good. the third is for ease of maintence. They can swap a engine on a 747 in under 12 hours and 3 tech's and a crane and the 747 has a 5 th pylon so they can even take a spare with them.

The biggest limitation with props is the tips going super sonic.

Only other thing to note is that Indian has gone with EASA certification. So thats a quarter of the orders now being officaially certified seperately.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I just had to go look up the 5th pylon thing. I thought you were joking! https://www.flightradar24.com/blog/how-qantas-ferr...

Anyway thanks for responding. On the FCC is it actually a side by side thing (i.e. one handles instruments, inputs etc from one side and the other one the other) or is it more complex than that?
Would the other FCC still have been using the incorrect data from the AoA indicator?
Why was it only the captains side which had the stick shaker etc going off?

I assume from previous comments that the FBW planes use a 2003 voting system to decide a faulty system. A 1002 system therefore doesn't seem to cut it in terms of knowing which input / machine is at fault. Hence the pilot(s) become the arbiter.

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 5]

The effect of engine size on aircraft trim.
The larger size engines have been mounted further forward and lower in relation to the Center of gravity.
The larger engines cause more uplift as the angle of attack increases.
When the engines are mounted far forward of the center of gravity the uplift has a greater mechanical advantage and so a greater effect on the trim at higher angles of attack.
The complete solution is to move the engines back so that the center of the uplift force is under the center of gravity.
Now we have lift rather than trim upset.
The other effect is the trim upset caused by thrust below the center of gravity.
The lower the engine is mounted below the CoG the more mechanical advantage the thrust has in causing trim upset.
The complete solution is to raise the engine so that the center of thrust is in line with the CoG.

The perfect solution to trim issues with large diameter engines is for the engine center of thrust and the engine center of uplift to coincide with the CoG.

Unfortunately the world is not perfect and I doubt that the engines will be so mounted in the near future.
However the bare engine may in the future be mounted close below the wing with the fan close to the leading edge of the wing.
That will put the hot gases below the wing and make the engine relatively easy to dismount.
The major bulk of the engine is ducting for relatively cool bypass air.
The ducting is relatively forgiving. It may be easily split to allow the engine to be dropped out.
The inside does not have to be the same shape as the outside, the outside may be in the form of an airfoil to generate added lift at all times, not just at high angles of attack, and the lift would not cause major trim upsets.

I consider many of the objections as engineering challenges to be overcome rather than reasons why a concept will not work.

To date there have been over 300 lives and billions of dollars as a testament that the present trend of mounting physically larger engines further ahead and lower may not be the best idea.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

In a previous thread there was a system diagram with the setup.

Each type is different. Fbw is a whole different setup.

There is fail safe, fail passive setups.

In theory it's relatively simple in a fail passive setup which the 737 is meant to be, but in practice there are more links than they tell the pilots about.

The sensors don't directly connect to them. They go to an air data computer. Which then outputs to various box's. The stall protection has two boxes one left and right which can trigger the stick shakers. When both shakers are on then it arms the hydraulic stick push system which is a piston which pushes the control column forward. These maybe separate boxes or combined with others system management boxes depending on the type.

A switch to running everything off one air data computer might also have helped. It all depends how it was wired.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

And an interesting bit of info I found out yesterday.

The 737-200 300 and 500

All had 2 electro hydraulic trim motors driving the stab. One was used by the auto pilot and systems and the other was only used by the electric manual thumb switches.

The two cut out switches on the MAx are a legacy from those days you could independantly kill one or the other on the classics.

On the NG they replaced the two drive units with a single electrical screw jack. BUt kept the ability sort of kill either manual trim or system trim independantly.

And the max which is now electrical single screw jack and two switches in series so they didn't have to change the cockpit layout. Either switch will kill everything.

So in the classics you had two additional failure layers before you were into pilot brut force trying to manually trim the aircraft and you also had 1 layer of redundancy. Which complies with certififcation and gets you into a low level of failure mode easily into less than 1 in 1 million flight hours.

NG removed the redundancy layer but retained one failure layer.

MAX no redundancy and no failure layer = two fatal accidents with the trim system.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I assume with two motors there must have been some sort of interlock to stop the two trying to go in different directions at the same time. I guess in the MAX this was in the electrical switch and relay wiring diagrams posted some time ago.

But still makes the point that the manual system was able to be standalone and de-coupled from the FCC before and now it isn't.

I still think this will be a sticking point between Boeing and the regualtors or the European ones anyway.

Some re-wiring might be needed....

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 5]

there isn't two motors on the max.

Its just one big electrical screw jack.

The classic had one motor for the automatics and a completely independent system and motor for the manual trim system. When you use the manual trim thumb switch it kicked the automatics out and took the other motor off line. Per say the manual system was never connected to the automatic system apart from a kill relay. But then again the classic didn't need to have any flight control augmantation to sort out dodgy aerodynamic effects.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

just a couple of updates it seems the lionair report is out in November and they are doing the tidy up meetings.

https://www.wsj.com/articles/indonesia-to-fault-73...

Also the new boss of the FAA has had a pole of the max in the simulator with the new software. Whats telling for me is the fact that nothing has been said about none normal handling. And Ryanair are saying Feb/March.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Although this story https://www.seattletimes.com/business/boeing-aeros... was in March, it still resonates that the pilot was the fail safe, but no additional training was mandated. I know there is the " A properly trained pilot..." thread in this, but if you're going to sell your airplane worldwide then you need to sell something that still works when the level of training may not be at US / European levels. It does note that pilots, especially newer ones, now expect a level of automation that may not have been present in the MAX.

Still doesn't mention the fact that the manual back up system may not work due to the size of the stabilizer.

I'd not heard of this one before https://www.flightglobal.com/news/articles/sensor-... but shows that even 2003 voting doesn't always work if the 2 are frozen solid. Like a lot of incidents there were a LOT of other things not being undertaken correctly, but does show nothing is infallible.

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 5]

Re the 5 pylon 747 there was a 4 engine B-17 WW2 bomber converted to use a 5th engine for testing purposes by P&W in late 40’s for turboprops. All 4 recips would be shut down with the turboprop maintaining flight power. I saw the airframe at the Bradley museum in Windsor Locks early 70’s sans the 5th engine but it since has been restored to original production config. Not a 5th pylon but still pretty cool. Here is a brief story about it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

2
https://newrepublic.com/article/154944/boeing-737-...

It's more about the management side of the disaster, but seems to confirm some speculations in the thread above - there was a real incentive to not retrain pilots for the new system, so it was omitted from some manuals, the MAX design was built into an existing FAA certifiaction and others.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Quote (MartinLE)

I don't think I would just take everything reported here as factual, but nonetheless it's consistent with my experience. No matter the management culture promoted by a company, it's subject to change drastically and rapidly because management personnel change and bring different priorities, skill sets, and experience (or lack thereof) with them. Warren Buffet once said the he would only buy a company that an idiot could run, because eventually an idiot would probably end up running it.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Some recommendations from the NTSB, none of which are related to modifications necessary to get these ships back in the air.

https://www.ntsb.gov/investigations/AccidentReport...

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Maybe not but my reading / understanding of this is that the NTSB found that the testing of the MCAS simulated only the resultant AND action and didn't actually simulate an AOA input error / disagree which resulted in multiple alarms and actions as the incorrect data spread to other systems such as the stick shaker and other alarms. It's not clear ever if the Boeing assessment or testing realized that the AND just kept on happening 5 seconds after trimming back.

Also the assessment assumed or was based on the ability to return to steady flight using the available column ALONE or trim. That's the key one where it's been shown you can't do that and you can't manually trim.

It is now recommending basically that ALL the 737MAX safety assessments which rely on the pilot(s) making "immeadiate and appropriative corrective actions" are reassessed and incorporate design improvements, procedure and appropriate training....)

So now Boeing and others need to not only consider the impact of an event ( uncommanded AND in this instance) but also the impact of the initiating event (bad data, failure of instrument etc) on other systems which result in multiple alarms leading to pilots finding difficulty in identifying the root cause and corrective action.

WOW.

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 5]

It's part of the grandfather stuff. They only have to test the system changed. They don't have to do the big picture.

Over the years they have added multiple additional aural warnings TCAS egpws and the like go through the cockpit speaker, gear warning has its own horn. So does airspeed high. Stick shaker generates its own noise. I haven't yet seen anything formal about which alarm has priority. Your meant to use "airmanship" to decide which one to tackle first.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

A NG related issue

https://www.reuters.com/article/us-usa-boeing-faa/...

They more than likely use the same on the MAX but no MAX airframe will have the hours to be anywhere near it being an issue. But they may have to replace the pickle forks on the parked aircraft before they are delivered or agree to pay for it at the first heavy check.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

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 5]

(OP)
Thank you for linking the update. That is a very interesting read. The NTSB is getting out ahead of the FAA here, and I'm glad they are doing this. By sharing its findings as quickly as possible, rather than delivering all results of the investigations at once in the final accident report, they can emphasize the similarities in the accidents and the design errors that led to them. This will have repercussions with all of the world authorities examining the Max certification, not just the FAA. If it also ties the hands of the FAA to offer no easy backdoors to Boeing, then it's also good.

This particular document, despite its length, is actually a highly distilled set of conclusions and recommendations, which reveals plenty of what the NTSB thinks was going on in those cockpits. There was a lack of sensible information being provided to the crews, no training to deal with the particular situation, and low odds that they would be able to sort it out before the problem evolved beyond the point of recovery. The NTSB is clearly coming down on the side of bad design, and I am pleased to see that they lay NONE of the blame at the feet of the flight crews.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

(OP)
Hi Alistair,
The Reuters article you linked just makes noise about a very minor and completely unrelated issue.
The affected aircraft are old and heavily used. The tiny cracks were found because there is a commendably thorough and detailed inspection program being used to look for this damage, and find it long before it becomes a threat. This is evidence that the system works.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I realise that, to be honest I just thought it might be of interest.

I have had my finger inside a crack in concordes tail and it flew a week later. And I worked for 2 years on nonlinear fea models and validating my models of cracks in nuclear pressure vessels. So I am quiet familiar with the condition monitoring side of things for allowing acceptable cracks.

If the pickle forks are the same though on the MAX and the life of them is reduced then the undelvered aircraft will need contract changes to account for this or the issue rectified before delivery. Changing the pickle forks will required the wing box to come off. All the NG's it is now the operators problem for inspections and rectification. MAX it will significanlty increase the life cost of the aircraft so while they are still on Boeings ownership books its their problem to sort out. With any luck it will be an material issue with a batch of pickle forks. If its a design issue then its another thing on the list.

On the subject of blame... Accident investigation never lay blame as such they anlaysis what happened and then recommend to stop it happening again. Blame is only decided by courts of law. And quite often it doesn't go the way people expect.

The Shoreham accident in the UK in 2015 had quiet a few of us suprised at the outcome of the court case and was at odds with the accident report.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Quote (SparWeb)

There was a lack of sensible information being provided to the crews, no training to deal with the particular situation, and low odds that they would be able to sort it out before the problem evolved beyond the point of recovery.
Right. Also, they note in some way something I learned many years ago. Given equal amounts of education and training, some folks have a better (or different) understanding of things than others. Also, Some are better troubleshooters than others and some perform better under pressure. That's just the way it is and to expect a pilot to always understand exactly what might be wrong with their airplane, take appropriate action, and absent that, to blame them if the thing crashes isn't a helpful philosophy.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I have flown with the phyco nurse of one of the Cray brothers. I have also flown with the number 2 celloist of the royal philomonic. Both have a completely different time scale and problem solving thought process than I do as a Mech Eng.

Btw signed both of them off into the lhs as captains of commercial jar25 aircraft

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

H'mm 7.5 Bn of trade tarrifs kiss good bye to max flying again in easa land for the next year.

It seems us punters are going to test the fix.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Boeing 737 Max Safety System was Vetoed

Boeing has provided a complaint by an engineer to the DOJ as part of a criminal investigation in the design process of the Max

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I agree with the comments on the assignment of blame by the courts- it can go either way. As a "good citizen" one is expected to presume the assignment of judges is random and the selected judge is not compromised, but with a major corportation facing an existential threat together with the potential " national security " implications of having the banckrupt assets purchased by mandarin-speaking entities, it is possible that "dirty tricks" may be rationalized.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I didn't realize what this $7.5Bn was about, but here it is https://www.bbc.co.uk/news/business-49906815 Now in theory it shouldn't impact the issue with Max, but .... The 10% duty on EU aircraft being a particular issue. I had heard something about whiskey being taxed at 25% but thought it was just an ongoing tit for tat trade deal thing, not directly related to aircraft. Note that there is also an ongoing US govt aid to Boeing issue being waged in the WTO to be determined later. 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 5] Price of Scotch is going up, time to start hoarding. ---------------------------------------- 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 5] well I do feel sorry for the malt drinkers in the USA. Bourbon is rank. Airbus already have the Mobile production site for A320 and A220 so it doesn't really matter for them. Airframe orders are done 5-6 years in advance so its the USA consumers who will have to foot the bill. Will make zero difference to sales they already occured 6 years ago. And the max won't be flying any time soon for quiet legitimate reasons. Plus USA has a finding against them from the WTO for similar reasons so it just going to hurt everyone. But thats into politics not engineering or aviation... RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Quote (dgallup) Price of Scotch is going up, time to start hoarding. I switched to tequila years ago anyway. Brad Waybright It's all okay as long as it's okay. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] just had a beer with someone that has flown the MCAs version xray software version... All he will say about it due to extensive gagging orders is... no comment RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Unless there's some order in place ordering that these records to be impounded, I would think that any airline would immediately begin to review maintenance records (and anything else they think might be salient) following an incident. There are no specific allegations of wrongdoing other than to say there might be some wrongdoing, and also that 3 years ago some folks weren't qualified for their jobs. It just sounds like spectacular journalism to me. Brad Waybright It's all okay as long as it's okay. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] what's the "xray software version"? some sort of code? 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 5] There have been that many iterations going through. It could though be a form of humour as a 8 digit software version is quiet hard to remember. Looks like they have released the EASA verdict on the process though. Arguments over what level of DAL testing is required I suspect is the crux of it. Maint and training records are sealed pending the investigation tuning up and collecting them. All airlines would love to go in and make sure that no bit of paperwork is incorrect but they can't, in EASA the SMS is meant to check everything within the airline. You then have external audits by the regulators to further confirm it. Every ICAO country has a law in its Aviation act which makes it a legal requirement after a fatal accident. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] on the pickle forks subject it seems that it might have something to do with a mod to fit winglets to reduce fuel burn altering the loading profile. Currently they are getting 5% failure rate with inspections. But most aircraft with the winglet mod are long route machines so are under 22000 cycle inspection trigger point. To fix it will take a heavy maint hanger plus 3-4 weeks. Unfortunately there are only 25 spare sets in existence and the NG production has shut down. They are meant to be lifed for 90 000 cycles the same as the hull but aircraft with 25 000 cycles are failing. This will cause even more issues to MAX customers who were upgrading their NG fleet. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] That seems optimistic. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] It's a matter of how you bring the message. I understood that American Airlines previously extended the flight cancellations until December 3rd, 2019 and now decided to further extend the cancellations until January 15th, 2020. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] True, but it's not up to American Airlines it's up to the FAA. I assume AA has some new information from the FAA that leads them to believe that, but it seems optimistic given the scope of the software and hardware issues involved. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Probably a revision of their Dec.3, 2019 deadline. The new information was probably; "Forget the December 3 return to flight." I suspect that this announcement has more to do with full disclosure to the securities regulators than with the Max 8 schedule. I won't be surprised if a month from now there is a similar announcement pushing the date back another month. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] "...what level of DAL..." It would seem to be DAL = 'A', as evidenced by two Catastrophic incidents. Simplest approach to reduce the appropriate DAL involves rewiring the switches. But they'd then open the Training can of worms. That's a nice corner that they've painted themselves into. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Not only training the pilot response time to certain events has been blown out the water. Which will have other knock on system requirements. Plus also there are issues with the cockpit alerting systems and sensory overload. If its DAL A then I believe your looking at another 9 months min before it fly's again but more likely 12 months. And the media releases are I think are more to do with required financial updates than anything to do with the process of recertification. Oh and the pickle forks are not the same as the max or classic pickle forks so they are having to restart production of them as they only have 25 of them in stock and the failed aircraft have already used them up. https://gizmodo.com/how-these-simple-scimitar-wing... is one form of winglet The other is called blended https://www.boeing.com/commercial/aeromagazine/art... United got the scimitar winglet fitted but I think Air southwest has the blended. Ryanair in Europe has the blended as well. There doesn't seem to be any meat out there yet what's causing the cracking. https://leehamnews.com/2019/10/08/boeings-737-in-a... How long that will take to restart production you guys will know better than me. But this is going to have huge effects on regional fleets around the world if it stays at even 5% failure rate. All the excess capacity has been soaked up covering the MAX. You might think that this doesn't have anything to do with the max but a major issue like this in the fleets that the MAX was meant to be replacing is a huge issue there is just nothing to replace the aircraft with without completely retraining cockpit and technicians. And even then unless your going to start pulling coal burners out the desert there is no modern hardware available that can take a 737 load. It will be the final nail in the coffin for quiet a few Boeing operator airlines. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Quote (Alistair Heaton) There doesn't seem to be any meat out there yet what's causing the cracking. From articles I've read, including the leaham news one, it's because the winglets change the lift distribution so that the spanwise center of lift is further out toward the tips and thus the moment at the root is higher even though the total lift is about the same. [edit- you think they would have accounted for that after developing the idea for about 30 years]. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] There is a difference between a post production mod fitted using a third party and a OEM fitted winglet. The level of analysis is far less. The OEM doesn't care because they carry no risk. If its fitted as standard as they are in the MAX then it is their problem similar to the MCAS. As I said I haven't seen any meat on the subject only sensible speculation on the cause. If it does turn out to be post production winglets fitting then its not just a problem for the NG there are quite a few other types across the whole lot of OEM's which could have problems. Failing at 22k cycles though instead of 90k is a huge reduction in life span. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Its been forever since I looked at an S-N diagram. Can anyone fresh estimate the change in peak stress that life reduction corresponds to? RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Its machine Al alloy and it will be at the dirty end of the SN curve due to weight saving. They will have inserts in the holes as well and if the vector on them changes it throws their effect out the window. That said the safety factor would have to have been used up as well. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] (OP) Thank you AH for the report link. They are not too kind. While they don't write it in one sentence, because their mandate was not to find cause, the JATR put the two statements in sequential sentences, so that it is pretty obvious. Recommendation 3... "non compliance"... FAR 25.201, 25.1329, 25.1581... Ouch... I suspected, and this corroborates. Recommendation 5... "In some cases, [the FAA's] BASOO engineers had limited experience and knowledge of key technical aspects of the B737 MAX program." Recommendation 10... Parts of the FAA were kept in the dark. The different branches don't have perfect communication with each other, so if Boeing didn't tell the FSB about the MCAS, the BASOO couldn't be counted on to do it either. During the certification process, a decision was made to remove information relating to MCAS functionality from the draft Flight Crew Operating Manual (FCOM). This decision meant that the FAA Flight Standardization Board (FSB) was not fully aware of the MCAS function and was not in a position to adequately assess training needs. This is just some stuff that stands out in the first 20 pages. The whole report is quite the truckload of complex information. It will take a lot of time to process it all. It is also written for a certification/regulatory audience. Not easy for the public to read. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] There are two very distinct sides to the report. There is the original certification process and then there is the problems with the actual machine which are used to reinforce the findings. There is definitely a link between the reports releases and the changes in Management at Boeing. Although to be honest I don't think the changes will do Boeing any good helping getting the problem solved. They are still using lawyer talk on all media releases and pushing that all they need to do is update the FMC software and the aircraft can fly again. If you go by the recommendations then the whole of the fight control system, flight instrument failure modes and cockpit alerting system will have to be revamped. Which will then trigger the training aspects of the report. But the report I would say is a good reset to the whole wide industry and regulation. At least it will give the regualtors the ability to demand resources to be able to do thier function properly only time will tell if they actually get those reasources. I agree that although the document is public its pretty heavy going for even for those within the industry. Well there are managemnt changes within Boeing I susepect another announcement is going to be coming about the software fix is going to cure everything. I predict there is no chance of it flying again this year and in 2020 it is 50/50. I wonder when they will bite the bullet and shut production down. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] (OP) I noticed without much surprise that after the AD was issued, many 737Max operators were able to fly them to a storage site on ferry flight permits. What is unusual now is that there are some still being relocated in this manner as the delay of the grounding gets longer and longer. I expect many operators in northerly climates (Norway, Iceland, etc.) will prefer to park their fleet in warmer, drier countries during the winter of the northern hemisphere. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Surely this is already the most momentous grounding in the history of commercial aviation. Yes the Comet I grounding which read across to the Mark II was permanent, but the quantity of aircraft, finances, and passenger flights affected was tiny by comparison... even when scaled according to the relative size of the commercial aviation markets in 1954 vs 2019. Am I wrong? "Schiefgehen wird, was schiefgehen kann" - das Murphygesetz RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Are they still suggesting the planes can fly without retraining? RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] (OP) Only Boeing ever "officially" said that. If they still are saying that, it's unlikely that they'll be listened to at this point. The recent report from the joint task force really nails the coffin on many of the assumptions Boeing used to grandfather the 737 Max. Transport Canada has already (very early on) made a statement that they do not believe the Max can return to flight without special training for pilots. I can't be certain that the 737Max won't still be re-certified under the same type certification rules, but the scrutiny is obviously so highly elevated, that I really don't see how training could possibly be avoided now. [speculation alert] Perhaps they could circumvent the training requirement with a complete re-vamp of the auto-flight control system, plus the attendant sensors, manual trim and Mach speed trim system, but that would take more than a year, so either way they've got a big hill to climb. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Aye but there are some pretty restrictive requirements to ferry them. There has just been a few flown from Iceland down to Spain and they went the whole way at FL250, 250knts and flap 1 which would have kept the MCAS turned off. The other issue with training is that it seems the data pack for the sims was complete and utter garbage in certain areas of the envelope at simulating the relevant situation. And the assumption that a NG sim will do for any training is also out the window. That is one of the reasons for external test pilots to do flights before recertification. Oncce done they will then certify the sim as valid. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] So Boeing is able to meet their delivery deadlines even though the aircraft are unusable. Bill -------------------- "Why not the best?" Jimmy Carter RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Focusing only on economic penalties, will Boeing still be requried to reimburse foriegn airlines for continuing lost flight time if the FAA approves flights but the foreign regulators do not approve? The change of the CEO occurred concurrent with the release of the report. "...when logic, and proportion, have fallen, sloppy dead..." Grace Slick RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] (OP) That's for the lawyers to decide. You can be sure they're already working on it. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] I would assume yes, since the foreign regulators have lost confidence in the FAA and thus likely won't stand by their approval. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Until they deliver the aircraft the penalties will apply. There is a bit of history on the having different versions for each regulation area. In the old days it was a major pain moving hardware. So areas required certain mods done and others required them to be removed. I really can't see anyone be happy recieving a pre world wide approved aircraft because it will lock it into the FAA region unless it's updated later. Production slots are sold years in advance and you know your serial number before a single bit of metal is cut. You now have the situation that the most loyal customers who bought in early are going to get the lemons of the production run. I don't know how happy USA punters will be flying on it either if they know the rest of the world are saying it's not completely compliant yet. I really think the "the pilots should have just flown the plane" keyboard warrior's will have the same effect changing thier opinion as they did trying to nail everything on the pilots and get the aircraft flying again with no changes. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Amazing how little damage this has done to Boeing’s share price. They’re up on a year ago, up 200% on three years ago, and up 1000% on ten years ago. I didn’t realise their civilian planes were such a small part of their income. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] Airplanes account for about 60% of Boeing's revenue, so it's still pretty important, but only one quarter of that is from the 737 Max. Their expected revenue for 2019 is expected to be down about 5 to 10 billion out of a total$93 billion for 2018.

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 5]

This is also still in the investigation/review phase. If the FAA or foreign regulators comes back and definitely says major modifications are needed, I'd expect the market to react then.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I wouldn't want to be an executive in charge of aircraft purchases with a fleet of Max 8s on order.
Do you accept delivery of the aircraft and hope that they will be cleared to fly before the costs of not flying get too onerous?
or
Do you cancel your order and go to the end of the que and wait additional years for new aircraft from either Boeing or Airbus?
Just when you thought that managing an airline was a science you find yourself in a high stakes game of chance.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

They won't take delivery of any airframes until they are certified to be flown.

Normally there is a deposit paid on confirmation of the order which is when your serial number and production slot is issued.

Some make alot of money selling early production slots.

Depends on the purchase contract if you can cancel and get your money back.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

The only connection I have with airplanes is as a passenger, but I live outside of Tulsa under a flight pattern for TUL and all the remaining American 737 MAX are being ferried here from storage at Roswell as Tulsa has the largest maintenance facility. I thought you might like to see the two most recent flight patterns (both in early Oct) if you hadn't seen them before, according to Flightaware.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

(OP)
Thank you RVA,
That article about the e-mails puts a dark tone on the development process.
Forkner and Gustavson discuss the MCAS problems as if they did not think they were accountable for the problem. In the end, they may be held to account more scrupulously than they expected. Especially if they're called back to testify to congress (again).

How many of us engineers have had a similar exchange by text message or e-mail like this? The actual exchange is reproduced in the PDF below (from Reuters):

www.sparweb.ca

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Mind you this is only the witch hunt. I will admit I have zero clue about the process in the US. The little I do know is from reading about the shuttle disaster and reading the Truth, lies and o rings by Allan Macdonald.

And unfortunately there seems to be quite a few similarities in the time line and management input into the engineering.

A lot of us in the industry are more concerned about how and when they are going to get this Frankenstein ship flying again. They still don't seem to have grabbed the bull by the horns and admitted that they screwed up big time in not just the MCAS area.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

https://www.msn.com/en-au/news/other/exclusive-eur... claims that European regulators think the Max will be certified for flight in the first quarter of next year

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 5]

Its just a statement saying when the earliest time it could be flying is.

They have test flights scheduled for December. If they don't have any issues at all in those flights the earliest they could see the fixes being certified is mid Jan.

Once the airframe is certified again then they can talk about the manuals and training side of things.

But EASA is famous for these announcements on time scales. They have to say something because some regulation or politician requires a statement. So they make one which means absolutely nothing and ties them down to not a thing.

What I suspect is happening is that Ryanair is putting pressure on the Irish side of things because they are well and truly screwed just now. Aircraft leaving and nothing getting delivered, crew getting released on unpaid leave bases closing. And this is then getting fed through to EASA. I don't know for sure though, its extremely tight on gossip for the whole thing now.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Bloody certificates. It’s all anyone cares about.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

(OP)

Quote (Tomfh)

Bloody certificates.
Yeah. Here, I can print one off for you in 30 seconds... ...there, done, yer good ta go!

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

All I am hearing is ignore everything you see released by all parties on timings until after the crash reports and the test flights. There is some required statements due to the financials coming up and everything is geared around a strategy of dealing with that and stock price.

And the financial stuff and pandering to share price is the whole reason why they are in this mess in the first place.

There seems to be a race on between the financial stuff release and the release of the first crash report which is due by the end of November.

The circle of the legal process in the USA surrounding various investigations by multiple groups of people and what the end result of those investigations I will admit is a huge mystery to be honest to those of us in EASA land. Will it be the small individuals that are used as collateral damage or will they go for the people who were actually driving the process. Or as I suspect it will result in absolutely nothing.

The relatives of the lionair crash are being briefed on the final report and it might be released on the 29th of October.

Its looking likely that the FAA flown test flights won't happen in Nov. If they don't happen the EASA ones won't happen in December. If the conclusion is that MCAS is an anti stall device then your looking at easily another 6 months more likely a year. If the handling without it is deemed none compliant then they are going to have to certify the whole Flight control system to a higher DAB level and build in another failure layer before the pilots have to manually fly it. I have zero clue how long that would take.

If they don't have movement in Nov its likely they will have to shut down production which has huge ramifications for after they do get it flying again.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

they haven't put the full report up yet on the AIBB site.

http://knkt.dephub.go.id/knkt/ntsc_aviation/aaic.h...

To note its 6 out of 25 recommendations that are pointed towards Boeing.

The maint records were as expected utter garbage with 30 days worth of records missing.

A valid complaint of pilots not writing up a snag with complete information for the techs to work with. Please note this is a world wide issue with pilots recording utter bollocks in the tech log and then disappearing off leaving the techs to try and find out whats wrong. In most aircraft these days the ecam and fadec systems record the last 50 hours of flight and they can play it back and see everything that happened. The MAX doesn't have a ECAM system because that would have blown grandfather certification out the window and required sim training.

And a Florida based overhaul facility apparently sent an uncalibrated AoA which was then fitted to the aircraft and the tech didn't check the calibration after fitting as per the Boeing maint manual.

So as usual a series of holes in the cheese, some human factors both pilot and maint, dodgy part involvement, and the issues we all know about with the original design.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Final report is out for lion air online.

http://knkt.dephub.go.id/knkt/ntsc_aviation/baru/2...

To note the dodgy repair shop in Florida who was the first slice in the cheese closed yesterday the moment the report came out. It did this itself and wasn't closed by the FAA.

Update on the part refurbishment shop, It did a deal with the FAA to shut without further action by either party. But per say it was compliant with its approvals. It's just that the approvals were granted by the FAA without it being compliant without the relavent requirements by the FAA.

https://uk.reuters.com/article/us-xtra-aerospace-b...

Seems a bit strange to wait 10 months and only do it on the day of the report coming out.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

(OP)
From the accident investigation report:

Substantial shortcomings in the crew's response to the situation.
• Emergency was not declared
• Checklists not followed (not even consulted)
• Communication breakdown between pilot and first officer
• Incomplete pre-flight briefing
Maintenance problems:
• The maintenance engineer released the aircraft for flight with incomplete maintenance
• The AOA sensor that was installed was malfunctioning.
• The maintenance engineer that installed it did not properly verify its function.
• "the aircraft was released with known possible recurring problem."
• maintenance not performed to diagnose possible related problems
• "the engineers were prone to entering the problem symptom ... instead of reviewing the OMF maintenance message"
It also implies:
• deliberate falsification of maintenance records
(More on that below)

Shortcomings of Boeing's design are already known and reviewed by the investigation:
• Non-linear flight control forces at high angles of attack / high g load conditions
• No angle of attack instrument display in cockpit
• No AOA Disagree indication in cockpit displays (unlike previous 737's)
• No training available to inform any crews of the above differences
• Emergency procedure for AOA Disagree inadequate to resolve this accident condition
• No Abnormal procedure for MCAS malfunction
• Repetitive erroneous activation of MCAS was not considered in the system Functional Hazard Analysis
• Full operational envelope of MCAS was not considered in the system Functional Hazard Analysis
• Full operational envelope of MCAS was not tested by simulator or flight crews
• Many more, but that's enough for now...
Investigators also encountered this:
"The engineer in Denpasar provided to the investigation some photos of the SMYD
unit during an installation test as evidence of a satisfactory installation test result.
The investigation confirmed that the SMYD photos were not of accident aircraft
and considered that the photos were not valid evidence."

and this:

"The BAT LMPM required the engineer to record the test values to ensure
that the test results were within tolerance. The engineer did not record the value of
the AOA angle deflection during the AOA sensor installation test."

My interpretation of the findings on page 185-188 (though not the investigators' statement) is that the maintenance person did not perform the required test, and filled out a release for flight without either testing the equipment that had been replaced or even finding out if it was functional. That person later provided the investigators with false evidence of doing the test in an attempt to back up the false claim.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Yep.

But also the refurbishment company using none OEM approved calibration equipment which the FAA had approved with no written procedure.

Also reading between the lines the fo was what we call a career fo. And also significantly older than the captain. It doesn't make for good cockpit dynamics.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Quote:

Update on the part refurbishment shop, It did a deal with the FAA to shut without further action by either party.

Quote:

But also the refurbishment company using none OEM approved calibration equipment which the FAA had approved with no written procedure.

Quote:

The FAA order was part a settlement agreement with the company in which it agreed to waive its right to appeal the revocation to the National Transportation Safety Board or any court.
Reading between the lines on this: It looks as if the FAA doesn't want anyone looking too closely at their shortcomings in this part of the Cover Your ASSets game.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

It's pretty normal accident report in relation to maint and crew standards from a developing area of the world.

If you look at other reports on the Indonesian accident investigation board you will see a common theme. I expect the Ethiopian report to have similar issues. But with it my gut feeling is that it was a bird strike, so the maint side will not play as big part.

What this report has highlighted is that it's not just the aircraft certification branch of the FAA which has issues. If the common approvals of FAA maint facilities is also thrown out the window it sets the common standards and approval world back 20 odd years and vastly increases costs for everyone.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

On a side note with a tentative link to the MAX ie its engine type. The LEAP engines on the A220 latest software upgrade seems to be setting up a resonance at high altitude high power settings which leads to uncontained engine failures.

https://www.reuters.com/article/us-airbus-a220-exc...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

(OP)

Quote (Alistair Heaton)

The LEAP Pratt& Whitney engines on the A220
I don't see how this is related.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

sorry I got the wrong engine type. I was just very interested in it as I have been flying my bum off thanks to ours getting sorted.

Anyway to get the thread back on course in this link the accident report and regulator review JATR is discussed. Some interesting stuff and I suspect a lawyers dream brief.

https://www.satcom.guru/2019/10/flawed-assumptions...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Maybe I missed it.
Looking through the Satcom Guru's article I didn't see any mention of the inability of the crew to trim with the hand-wheels.
Has there been any word on a response to the excess manual trim forces?

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

No, that's a bit of a elephant in the basement issue.

There is no regulation that requires to be able to manually trim across the whole envelope.

After that you get into what level of risk it is not being able to. And that's effected by the failure modes and next level down abilities.

Currently with the max its single failure = dump it on the pilots and CATASTROPHIC if they are outside the force window. How they are going to lower that risk level down to MAJOR is Boeings problem.

There are plenty of other jets of the same era 1960 which will have been the same in regards of not having full trimming over the envelope. But they had additional failure layers eg the classic 737 had two stab screwjacks, one of the pilot electric trim and one for the auto pilot and it had a cut out switch on the control column with full aft movement. So by the time they got to manual trim they were 3 levels down. The NG you could kill the AP input and leave the pilot electric trim turned on. And none of them had funny aerodynamic effects going on depending on which part of the envelope you were in.

Like everything else about what's happening the information releases are driven by financial regulations and everyone is keeping extremely tight on what's said.

Nothing is expected to be said until end of November when the FAA test flights will either go ahead or not as a lot of us expect. If they do then its EASA test flights next before Christmas.

From the stuff I have seen Boeing is determined to try and get away with only a software fix and a 2 hour ipad training session instead of an hour on the ipad. We shall see if the regulators accept that. If its physical system changes then we will still be discussing this same day next year

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

How do two separate independent screwjacks move the same stabilizer???

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Don't have a clue you would need to have access to the maint manual.

I presume it would be some form of differential gearing driving the actuator shaft.

The motor's are only a small part of the unit there is a great big gear box on the bottom of it on the classic. The NG is much smaller

I think this is a diagram of the NG screw jack.

to add I am not 100% sure about the top pic is 737 but anyway its a old school one can't find anything on line. The NG screw jacks are a 1 man lift, the 737-500 its 3 blokes a forklift a loads of swearing from what I have seen.

Found this which is a more generic diagram.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

(OP)
Gave the Satcom Guru a read myself tonight.
The clever guy - a bit smug - but most of the latest article concentrates on a detailed analysis of the JATR report and really hits home, too.

The part about the trim wheel effectiveness vs. cranking forces is definitely missing, WARoss, but it is very closely related to the other point that SG really does make: the 737 Max has no column trim cut-out switches. I admit that I hadn't caught on to this problem until reading it in detail just now, and what a difference that would have made. Imagine a system that allows a pilot to respond to "something wrong" before even being conscious of it. Those cut-out switches have been on the 737's all along, until the Max. They let the pilot stop the trim runaway by doing what he's been trained to do ever since first sitting in an airplane: pulling on the control column when the nose is low, and pushing when it's high.

Why were they omitted???

MCAS wouldn't have driven the stab so far out of whack if there had been a simple set of limit switches to prevent its continued operation while the pilots were already hauling on the controls.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Quote (SparWeb)

Why were they omitted???

Isn't that the point of MCAS - to manhandle the pilots?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Because MCAS is designed to work at high angles of attack caused by the pilots pulling the stick back.

If indeed Boeing are trying to limit changes as described I can't see it getting past the non FAA regulators.

I hope this issue has a big impact on looking much more at assumptions on pilot input (3 seconds to react) and the cumulative impact on the pilots of alarms following a failure of a single sensor.

Plus this 1 hour training I believe simply came to be too big a burden. You only have to look at the cockpit pictures of the max vs NG and it's a different plane.

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 5]

(OP)

Quote:

to manhandle the pilots?

I know you meant it in humour but I realize that you're partly right. If the cut-outs were there, then the pilots would be exposed to the non-linear stick-force trends at high angles of attack and high g maneuvers. So eliminating the switches (a safety feature AND a fault tolerance mechanism built into many system safety assumptions) were eliminated to prevent the bad aerodynamic behaviour from becoming obvious to anyone. Oh man this rabbit hole gets worse the farther down I go.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Remember mcas triggers both ends of the envelope.

Originally it was linked to AoA and g sensor. And this was deemed ok by test pilots grudgingly. Then they had issues with another area of the envelope and the g sensor was removed and its power and duration was changed. But it was never sent back to the full test pilot approval system and FAA wasn't informed.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

And this is the issue in a nutshell. It's the same aircraft with the same controls and pilot actions - except when it isn't.

The inability of Boeing to square the circle sufficiently is why we have planes parked up all over the world.

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 5]

Quote (Sparweb )

I know you meant it in humour

Not really. It was to keep the pilots away from the forbidden part of the envelope, wasn’t it? to avoid all the hassles of recertifying the plane and retraining the crews?

If the pilots know how to easily just turn it off it defeats that original purpose doesn’t it?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Or; It was to make an unstable plane appear to be stable.
It was meant to comply with the requirement that the force on the controls must be linear.
It can not have been a stall prevention/intervention system as that would have required more rebates, approvals and training. (A problem with the sarcasm font is that even if you use it, no-one recognizes it.)
We started with management overriding good engineering.
Will we end with politics overriding good engineering?

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

737 max Boeing failed a paperwork audit which will put back the start of certification testing of the fix by the regulators both SIM and aircraft.

737 NG pickel forks the failure rate is over 20% now and includes aircraft below 22k cycles. Plus also it doesn't seem to be linked to winglets. Not enough jigs or parts in the world for a quick fix.

787 O2 has some issue now with the pax emergency 02 system the explosive charge that opens the valve apparently has a 25% failure rate. Both Boeing and FAA know about it and have done SFA about it.

The altitude 787's fly at if you depressurize you have 5s of useful consusness without O2. And by the time you get down to breathable ALTs half the folk in the back will have the bends and brain damage with no 02. Not counting the ones that stroke out anyway.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I don't think you can get the bends without external pressure. Your last item is not unique to 787s, all planes flying at altitude have that issue; that's why cabins are pressurized and why pilots their own air supplies. Many people have died without cabin air pressure; see https://en.m.wikipedia.org/wiki/1999_South_Dakota_...

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 5]

Difference between cabin pressure and pressure at 38,000 ft is only about 60 kPa, so equivalent to 6metres below sea level. If you sat at 6 m underwater for a few hours is instant de-pressurisation to surface enough for the bends?

And 5 seconds is rather quick - the google consensus seems to be 15 to 20 seconds before you loose it and then 30 secs before hypoxia kicks in - but sure - it all happens rather fast and no way near enough time for the pilots to get down to 10,000 ft or so - assuming they've managed to connect to the O2 fast enough.

If you had a total decompression at 38 to 40,000 ft I don't know what the max descent rate is but prob 4-5,000 ft/min so 6 minutes. They always show it much more dramatically in the movies, but reality seems to be different.

Anyway a side issue - failing this audit doesn't sound good.

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 5]

You can get it easy enough that's why astronauts have to breath pure O2 for a few hours before doing an eva. The suits are much lower pressure than inside. It's to do with the partial pressure of nitrogen, pressure gradient and tissue half life for off gassing.

In the front we have a full face mask with mixed and 100% demand and forced feed.

Most places in the world you can head straight down to 10k and we can do 7k per min. There are areas where the MSA is greater than 10k so you have to level off higher and then step down. Think Everest.

Oh 787 will start at about 380 to cruise then end up at 420 or 430 after a few hours.

Our books say 5s useful high level brain function. And after doing the chamber training it's about right. There are plenty of YouTube vids showing it.

Normally most aircraft pressurise to 8k.

https://www.nasa.gov/audience/foreducators/mathand...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I'll buy the 5s useful time (I remember getting stuck after fitting the third piece into my 12-piece kiddies jigsaw puzzle in the chamber at Boscombe (and that was coming from breathing 100% on demand with a couple of mm of safety pressure to boot).

Altogether less comfortable with the idea that the oxygen concentration in one of those diluter masks we get in the back is going to provide much useful protection against DCI.

A.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I can hold my breath for well over a minute, why am I gong to lose brain function in 5s?

----------------------------------------

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 5]

I thought that also, dgallup.
Then I thought:
At normal conditions we have an O2 reserve in the air already in our lungs.
When the pressure drops suddenly we loose that advantage.
The air in our lungs is at the lower pressure.
If we had anticipated the coming drop in pressure and tried to hold our breath, the excess internal pressure after the drop may be enough to cause a ruptured lung.
It's been a long time since I have been exposed to the dive tables and warnings.
Can someone confirm the maximum safe pressure differential if a diver holds his breath when ascending?
Not the bends but physical damage.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Breath-holding is about not bothering to exchange air in your lungs with air outside your body (at the same pressure) and the reason you can do it for over a minute is because it takes that long for the CO2 level in your bloodstream and lungs to build to a high enough level to make you uncomfortable.

The depressurisation is different: The sudden loss of pressure on the outside of your chest will cause the air trapped in your lungs to expand and depressurise (and if, like me, your reaction is to open your mouth, excess air will vent off alongside the stream of mildish expletives). Either way, you end up with lungs full of air at reduced pressure, the alveolar ppO2 is correspondingly reduced, reversing the gradient which normally drives oxygen into your bloodstream, oxygen streams out of your blood into your lungs, and your sats plummet.

Enriching the air with oxygen helps to increase the ppO2 - but once you get to 100%, you run out of room to manoeuvre. After that, the remaining option is to cram 100% O2 into a tight-fitting mask at something over ambient pressure - and that's just not nice.

A.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Bill,

Barotrauma is a risk from as little as 2-3m (so 2-300 mb pressure differential. The damage is done long before you feel anything's about to burst.

A.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

When you hold your breath you are still consuming oxygen from the air stored in your lungs. After decompression there is almost no air in your lungs and oxygen will actually be leaving your blood in the the lungs. Its a concentration thing. I'm sure many people can last longer than 5 seconds before losing consciousness, though.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Thank you for both of your posts zeusfaber.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

The 5s is how long it takes your judgement to degrade after your lungs have been emptied (by decompression) or filled with oxygen-poor gas (by breathing in such an atmosphere). You'll still be conscious, just concentration/judgement/fine motor skills will degrade substantially. You get the same issues with confined space welding, for example.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Cabin pressure is supposedly comparable to 8000 ft altitude, which is just below the altitude sickness threshold for many people. Moreover, when you are holding your breath, you are facing a cooperative situation, and likely have had some preparatory breaths. In a plane, you either get explosive decompression or a gradual leak, as with the Payne Stewart case. Neither is necessarily conducive to optimum breath-holding scenarios.

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 5]

(OP)
You guys would feel right at home in a Gulfstream, then. The recent 4, 5 and 6 models fly up to 51,000 feet. They have to deal with nasty decompression scenarios. There is a specific case related to an engine throwing a fan blade that punctures the aft fuselage skin. There's a reinforced bulkhead between the passenger cabin and the cargo bay at the back of the fuselage. If that bulkhead wasn't there, the ensuing decompression would cause the floor structure under the passenger seats to burst upwards. The bulkhead has a door that you are not allowed to open above ~35,000 feet, if memory serves me.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Explosive decompression is extremely rare and usually linked to a major structural failure which alot of the time is fatal anyway.

The viz inside the aircraft will drop to under a meter and temperature will plummet down to -30 from about 20.

Most of the time there is issues with pressure high level it's either the outflow valve or a pressure seal going round a door. With both normally we feel a pressure change in our ears and everything is already being dealt with by the time the aircraft pressure gets to 13k and the rubber jungle deploys automatically. This does happen but it's not a yearly event for most pilots. I think my average is something about every 3 years.

If your aircraft is limited to fl250 you don't need drop down masks and they are not fitted. Most turboprops don't have them.

I think we have farted in the same chamber zeusfaber. Unfortunately it's not possible for civi's to do it these days I believe or if they can it's at huge expense. It's my top safety course so far in my pilot career. You only need to do it once.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Look on YouTube for pilot hypoxia there are loads of vids showing the chamber training.

There are also a couple of ATC recordings of controllers having to deal with getting aircraft down to a safe level with crew hypoxic.

The Helios accident in Greece was due to pilot error and pressurisation. It ended up running out of fuel killing everyone.

Also my point was more targeted towards both Boeing and the FAA knowing about a potential 25% failure rate of a critical safety system part and doing absolutely nothing about it.

I have a mate that fly's gulfs and one pilot has to sit with his mask on above I think it's fl340. And your right the SIM training is extremely involved for that event. Compared to my don mask, establish coms and decend followed two mins later taking the mask off.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Quote:

I think we have farted in the same chamber
Is that an effect of decompression that is never mentioned in PC society? grin

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Mate it was the most collosal fart of my life. I had been warned to go for a crap after lunch which I did.. You basically have air coming out both ends at once.

The is a vid of Clarkson from topgear doing a chamber run. He lets go a huge one as well. He had the nice controlled pressure reduction j presume they didn't want to risk hurting him.

Ours was 1 second 8k to fl350 which I think is about 0.6 bar drop. They could have gone faster as real life actually is but it gets very easy to blow ears out. They haven't yet managed to simulate dealing with a decompression after blowing both ears drums out.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

This 5s thing is the reason why your told to fit your mask before helping others. By the time you have fitted the mask to your child you will struggle getting things together to get your own on.

Most systems use chemical oxygen producers which need trigged. You trigger them by pulling down on the tubes. If you just put the mask on you will still get air movement but not 100% O2. The gas is hot, uncomfortable hot. There is one generator per seat bank with usually one extra mask for infants. If your a family of 4 with twins taking them on your knees and all the seats in the row are full. Move rows or sit either side of an isle.

These chemical O2 are a bastard to be honest the casing gets to 300-400 degrees when they fire. It used to be they could be transported on pax planes under AOG dispensation rules on DG. Thankfully that has been banned now after a pax aircraft had a fatal accident with one triggering in the hold and the hold suppression system had zero chance keeping it under control until they landed.

The 787 is a bit special because with it they changed to bottled O2 with one bottle supplying banks of three rows. You still have to pull the mask tubes to trigger it. I don't know how the arming of the system works if it's perm armed with the emergency battery bus powered or it turns on above fl100.

The issue is with the firing of the squib that releases the O2 from the bottles. Apparently getting the bottles out is a C check item where everything gets stripped out the cabin. Cost of replacing the bottles out of phase with the C check is in the region of 1 million dollars and the plane in the hanger for 2-3 weeks.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I'll go with the de-pressurisation thing. I was a couple of times on a pressurized jump aircraft which then purposely de-pressurized from about 2-3000 ft equivalent to 18,000 in about 5 seconds. The air went from normal to a complete fog where you couldn't see the other side of the plane. I don't recall the farting bit but likely got lost in the excitement. Mind about 7,000ft normal climb always seemed to trigger a rather noxious atmosphere in the cabin, especially on the first lift on a sunday morning...

Exiting an aircraft doing 180 knots was also rather interesting.... Slowing down to normal terminal velocity wasn't usual.

bottled O2 in a 787 eh?

A bit more background on the issue https://www.bbc.co.uk/news/business-50293927

I suppose the key issue, apart from the safety culture issue, is that testing a single use item is virtually impossible if you can't easily replace it.

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 5]

Its a weight saving feature.

787 has a humidity control system and also it gets clean cabin air instead of using bleed air from the engine compressors. Its cabin is lower at 6000ft typically.

From the mates that fly them, it works well and they notice a big difference. The ones that used to fly the 777 say when they get on a triple now it stinks like a workshop and they can feel thier eye balls drying out in the climb and sinuses clogging up.

Out with the emergency false tears and decongestant nasal sprays.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

oh on the subject of Decompression sickness and flying.

The FAA have a safety leaflet on the subject.

https://www.faa.gov/pilots/safety/pilotsafetybroch...

I too used to scuba dive a lot in Scotland at uni. I just tried to calculate a saturated body at 1 bar going to 0.24 bar at Fl350 and put it through the tables.

By my calcs you would need to sit for 16-24 hours on pure 02 at sea level not to get a CNS bend if you went straight from FL08 to FL350 in seconds.

And if you spend 8 hours at 6 meters under water on air then pop up your also into the trouble area of the graph. At 9 meters its 4:30 hours and 10meters 4 hours.

BTW those numbers are from 30 years ago and the current ones will be much more conservative. When I started diving in Scotland it was single 12 ltr steel cylinder, single DV, toilet seat ABLJ with fenzy bottle and a dry suit. We did have one club member get a bend after diving all day at 10 meters training so did about 5 hours underwater with 30 min breaks between dives and when we were travelling back to Glasgow over the rest and be thankful at 2000ft it hit her. The rest of us were fine which the medics put down to the boys finishing off the beer on the way back in the minibus.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Wouldn't get that experience these days - 40% nitrox is a real boon if you're doing back to back shallow bounces (and what's the chances of ever finding the Rest and be Thankful open to traffic these days)?

A.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

It is and it isn't.

The sim crash was the reason why they went for a frankin furter dual FCC setup. This is a "leak" into what actually happened. Dual FCC and dual sensors actually does nothing when the system kills itself in the event of mismatch and then dumps everything on the pilot and leaves the uncertifiable flight dynamics that MCAS was installed for still there. To get to the next level of failure you need 3 of everything. Which would take at least a year.

Right the next bit has zero factual content and is purely rumour from this side of the pond.

The FAA have been told that if the max can't be started to be delivered by Jan then Boeing is going to be split into Mil and space and a few other entities and commercial airlines are going to be on there own. Production will be stopped and Chapter 11 declared. All debt will be with commercial and liability. Pensions will be dumped for all production staff if working now or retired will be screwed. The blackmail factor will be the possibility of the type approval entity going which will result in basically all Boeing models loosing there type approval over night because there will be nobody responsible for engineering oversight. Which will mean every single Boeing in the world will have to stop flying overnight.

And the context includes EASA and the other regulators. The American market isn't big enough to save things which is why they are asking to be able to deliver and then sort out the training later. Basically the world aviation market is screwed if the regulators don't agree if the rumours are correct and they pull chapter 11. Airbus can't supply the product in the amount required so 45% of the single isle market 180 seat plus production has disappeared over night. Tis is extremely serious. Linked into the pickle issue with the NG potentially grounding a further 20% of that size with zero spare parts and worse extremely limited jigs to do the fix to the airframes. And long haul.... carnage its Boeings only plus point with 777 because the A380 is pish along with A340. A330 is sort of ok if you don't mind pax dying of cancer enroute because its so slow and climbs like undernourished penguin.

To be honest I really can't comprehend the amount of issues if the Boeing type approvals were to evaporate over night if it was pushed to that point.

It will be now certified in Dec I am 100% sure. My bum and my family (apart from the mother in law) will not be sitting in it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

That'd be amazing in a truly horrible way. Sorry we messed up, but do what we say or we'll declare bankruptcy and crash the commercial aviation market.

For an agency that's already lost a good portion of the public faith, if FAA hand-wave approves it due to those alleged threats, I hope serious consequences ensue.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

its not only going to be the FAA all the regulators in the world have their balls in a vice with this one.

The max will fly in December and it is absolutely nothing to do with it meeting flighty safety standards. Quiet what they will do when the next one crashes is any ones guess. Another one will crash more than likely nothing to do with the MCAS system.

I must admit I really don't understand all the different enquires in the US about the various stuff that's been spouted. It seems to me that if there is a chance of Boeing going bust the they will all shut up and stop the grandstanding.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I was under the impression that the conditions for bankruptcy would be determined by a bankruptcy judge, and its conditions are not determined solely by Boeing's objectives.The needs of the employees, pensioners, airline companies, and families seeking retribution are all considered by the judge.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Splitting Boeing.
This may limit liability going forward but it may be argued that the action was done to evade past liabilities.

Bankruptcy.
This does not imply liquidation. In fact it protects creditor's interests by preventing one major creditor to force liquidation to the detriment of other creditors.
Johns Manville emerged from over 5 years of bankruptcy and is still in business.
Celgar Pulp Mill was under bankruptcy for over 5 years before being bought out. The mill is a going concern today under a new name.
Under bankruptcy Boeing could continue to operate under the supervision of a receiver.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Quote (Alistair Heaton)

balls in a vice
...Interesting typo... or is it a Freudian slip

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

its a pretty common saying in UK English.

"balls in a vice
Somebody else has cornered you into a really tough situation, where you must now make a major decision between two things neither of which you want in the least.
They had his balls in a vice: either take the pay cut they were demanding from him, or be fired."

from Urban dictionary.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

We might see new aircraft with the Douglas Aircraft Company label yet out of this mess.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

(OP)
AH:
Usage may vary from one country to the next.
"Vise" is accepted spelling in some countries for a machine tool used to safely secure a piece you are working on.
"Vice" refers to the stuff you need AFTER work, that tends to be LESS safe...

Nobody said the Urban Dictionary was big on spelling nuttin'

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Fair enough.

UK and International English the tool is definitely spelled that way.

The Boeing MD merger is the root cause of this mess.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Maybe I'm being dense here, but why would splitting the company make the type approval certs invalid.

Surely they would / could be transferred?

Even with the 737 max disaster, Boeing makes money and other aircraft. It won't be allowed to just fold. chapter 11 is a bankruptcy protection mechanism which aims to prevent liquidation and allow companies to be sold / restructured.

As for how many law suits this would generate can only be speculated.

But something will have to give somewhere. I would have thought the type certification training is one way or some hardware mods.

3 FCC is also an option

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 5]

the splitting wouldn't.

The entity that ends up holding the type approvals after the split if it then goes bust is the issue.

Its not easy transferring them and it will involved a break in cover during which the planes can't fly.

3 FCC is an option and also 3 AoA also an ECAM system to deal with the 1960's warning and advisory sensory saturation which has been noted in the MAX cockpit. But realistically that's a good 2 years to develop for the max if they start tomorrow.

They are just running out of time and parking spaces. If it doesn't start flying soon then the production line will have to be stopped, labour released, suppliers will move on or possibly go bust and it will takes years to get back to the current skill and production rate, never mind the 72 a month they say they are going to ramp up to once they get the certification back. What that's going to do for quality is anyone's guess. They have issues already in that department.

The training is the next elephant in the room, 1 million per aircraft for air southwest if sim training is required. And there are also issues that current sims it has been discovered can't generate the control forces for the out of trim condition requiring the rollercoaster recovery to regain manual trimming.

Something has given,

Another huge question is if the passengers will travel in it.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Unfortunately I don't think the general public would pay much attention, if they even know this is happening in the first place.

If the design and training issues aren't sorted out but the various entities approve it, I would hope the pilots unions (I assume they have unions?) would take a stand and say we don't have faith in the aircraft? I imagine that'd cause a bigger stink though.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Quote:

My bum and my family (apart from the mother in law) will not be sitting in it.
I feel the same but I can't make that statement.
However, the next time I fly, I will probably do whatever I can to avoid a Boeing product.
Pay more, adjust my flying date, take a longer route.
The really tough choice will be if I am offered a fly-in job and the flight uses Boeing craft.
In some cases this may mean driving 200 miles and then riding the bus 200 miles.
In other cases driving may not be an option and the choice will be ride a Boeing or don't take the job.
I will be thinking hard about that one.
It is a matter of trust.
It is a matter of the perception that Boeing has a history of abusing grandfather privileges.
It is a matter of Boeing's response to the issues more than the issues themselves.
It is a matter of the cozy deal with the FAA that allowed Boeing to sign off on their own work.

Quote (SparWeb)

It may LOOK like a picture of some 40 airplanes, but it's actually a picture of FOUR BILLION DOLLARS:
Continuing production was an awfully big bet by Boeing that they could bafflegab the regulators with another less than adequate fix.
It look as if they are losing that bet.
This whole situation has repeatedly suggested that passenger safety has little priority in the Boeing culture.
Remember the old slogan?
"At Ford, Safety is Job One!"
Would it be fair to paraphrase that?
"At Boeing, Safety is Job None!"

There are a few companies that I have had more than one issue with and so avoid dealing with. I will suffer added costs and/or inconvenience to avoid these companies.
It is more a matter of company policy and company culture, and the companies response to a problem than the problem itself.
Welcome to my no fly list, Boeing.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

The cabin crew are making noises currently but the pilots are keeping out of it until the final product is again released.

In Europe there is various pilot organisations involved in the EASA side of things.

PAX are funny in what they will go for and what they won't. You are correct most won't have a clue what aircraft type they are sitting on. But the margins are that small on routes that if even just 5% of them fly with the competition on a route because they are using airbus then your stuffed. The bottom line for 80% of them is price. Its that 20% which can make or break a pairing. I am in that 20% who will actively make sure I won't get on one for a couple of years to see what else crops up.

They definitely know its happening. Especially in the USA it seems everyday some form of release is made on the subject or Boeing in general. I think I counted 13 different investigations ongoing plus the court cases from victims families etc.

Per say if the regulator says the plane is safe to fly then we will fly it.

I wouldn't avoid all Boeing models. The ones designed and built before the merger are good. Even the O2 issue on the 787 wouldn't bother me knowing fine that its extremely unlikely I will be flying over the china highlands in one and everywhere I might go in one they will be able to get down to 10k without issues. And explosive decompression is usually linked to major structural failure so we will be dead anyway. 757/767/747/77. 737 apart from the MAX all good. The new variant of 777 after this will be under a microscope so it should be fine as well.

Stopping production would have been fatal for Boeing and the 737 and would take years to establish again.

To be honest airbus are far from perfect as well. The biggest issue at the moment with the other types is the engines seem to be having issues.

An E175 had a trim issue the other week https://avherald.com/h?article=4cef2f7b&opt=0

here is the RT from it https://youtu.be/RzoEsM0L2CM

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Is it even possible to avoid flying on any particular equipment? Can't the plane shown on your ticket be swapped out for any number of reasons and you wouldn't know until you arrived at the gate? Even after you board the plane they can decide to swap equipment and then you are stuck balking with your luggage already on the other aircraft. Will they refund you ticket because you don't want to fly 737-M8?

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I don't have a clue what US t&c are for tickets.

If you use easyJet in the eu you won't be flying on a max so it's pretty easy to avoid for us.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Quote:

In some cases this may mean driving 200 miles and then riding the bus 200 miles.

Those illusory safety measures; have you seen the statistics on buses? There's less oversight on buses, by far.

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 5]

Quote:

Those illusory safety measures; have you seen the statistics on buses?
On the other hand, when several hundred workers a day are being transported in and out of the northern site, I was often concerned about the safety of the planes that I have flown on.
It is not uncommon to see three 737s on the ramp at the jobsite private aerodrome.
That is just one of several fly-in sites.
The mandate up there is get it done safely.
However at times the word is whispered around the site;
"The push is on and safety's gone."
When the planes have to fly, the push is on and often no replacement craft are available.
As far as the bus, it is not as bad as it seems.
Flying in still involves driving 150 Miles to the airport and often 30 or 40 miles on a bus at the northern end.
The time the bus caught fire during the daily 50 mile ride everyone just got off the bus.
You can't often do that on a plane.
The time that a driver of a bus ahead of us on a 40 mile trip to an airport had a medical emergency and made an abrupt right turn and came to a stop a couple of hundred feet out in the bush, there were no injuries.
The flights reduce but do not eliminate the driving and the buses.
There was not a high level of confidence in the flights to begin with.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Over the years I have had way way more scares getting to the airport than in flight. Usually I do 4 sectors every time I go to work.

I still have nightmares about getting driven to work in Saudi. Driving past smashed up cars with bodies hanging out blood everywhere. Never mind the near misses we had. Thankfully we had a very good defensive Pakistani gentleman driving us.

Anyway the FAA have just broadened the Pickle fork inspections.

https://www.regulations.gov/document?D=FAA-2019-08...

Currently its running at 38 out of 810 inspected which is 4.6% and they still don't know why its happening. Out of the ones that have been grounded none have been repaired and serviceable again. Once cracks found they are flying them back to Boeing to get fixed. But parts are still not available apart from the 20 that were in stock after the NG line shut down.

And with the MAX nothing heard rumour wise but the FAA is obviously feeling stuck between an anvil and hammer.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Interesting timing for a documentary in the UK next week (wed 9pm). The title gives an idea of the program but usually channel 4 do decent programmes. Will be interesting to see what they say. Doesn't look like it's going to be on boeings website.

https://www.channel4.com/programmes/boeings-killer...

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 5]

Unfortunately I will be at 25000ft when its on.

The NTSB hearing was on for the Southwest uncontained engine failure and explosive depressurisation accident last year.

As if the 737 design office doesn't have enough on its plate its now got issues with one of the engine types on the NG as well as the pickle forks.

Mind you in the current climate the FAA might just ignore the NTSB again.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Well the documentary was a little underwhelming. Mainly a Human Interest angle and also one lawyer working for some of the families of the Ethiopian airline crash got a lot of air time. A few nice graphics ok and when you see the original "dumpy" 737 flying you realize just how many things have changed.

Rather simplistic explanation of MCAS.

Only interesting points were a recording of airline pilots in a meeting with Boeing after Lion Air, when they basically said nothing was wrong and the pilots should have followed trim runaway procedures....

An FAA retired employee saying the FAA knew from the start that lack of simulator training was an utterly key aspect to the design. Some were uneasy about this but no real smoking gun. The revision training has now gone to 2 hours, but what's a hour when you're flying a new plane??

They had a sim session where they showed the manual trim control was either very difficult / not possible on the ET flight hence in their words the ET pilots "rolled the dice", by reactivating the trim. They were working on the basis of a bird strike taking out the AOA vane, but no evidence other thaqn the very abrupt change in the AoA signal.

A passing mention of the 4 second pilot response and the level of cockpit alarms and actions going on meaning the pilots couldn't respond in the way it had been assumed. To that extent I don't think the very small AOA disagree light would have been noticed even if it was there (which it wasn't).

So for a forensic, detailed analysis of the 737max issues - this isn't it.

Update: the recent gulf air show seems to have prompted a lot of chatter. This from the FAA is interesting - end March is "more conservative". https://gulfnews.com/business/aviation/no-timeline...

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 5]

MCAS to be renamed HAL-9000 ?

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

'I'm afraid I can't pull up Dave. You know as well as I do that would endanger the mission'

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Quote (VEIBLL )

“MCAS has to go,” a manager at Canada’s aviation regulator said in an email to global peers,

Quote (New York Times)

Mr. Marko’s email included a PowerPoint presentation expanding on his argument and outlining how Boeing might remove MCAS from the Max. He noted that public confidence in the Max was “LOW.”

Linh Le, a system safety engineer at the F.A.A., shared Mr. Marko’s message with others at the agency. He noted that the Canadian official believed that “MCAS introduces catastrophic hazards that weren’t there before,” that “it and the fix add too much complexity,” that “there have been many revisions to the software” and that “each was a band-aid.”

Mr. Le said he had similar misgivings about Boeing’s proposed fix for the Max. “I have held similar perspective (questioning the need for MCAS, at least from the system safety standpoint),” he said in the email to colleagues. It is unclear whether international regulators will take any action in response to Mr. Marko’s concerns.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Here is the original email plus some of the PP slides.

https://theaircurrent.com/aviation-safety/transpor...

As you can see from the article the MCAS stuff is the headline but there are several more issues in the works.

The way I see it now is the Certification Engineers are fighting back the media spin and getting there position public so they can't be accused of not saying anything, god forbid if another one spears in.

But if they just remove MCAS then it means they have removed a certification requirement that's been around for some 70 odd years just to save Boeings shareholders wallets....

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

This article about the DC-10 is about how weak certification oversight and making a 'safe enough plane' led to preventable crashes of the DC-10. So, in that way, no a new problem.

https://theaircurrent.com/historical-context/searc...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I actually think there is a typo in his e-mail.

He wrote " No matter what Boeing does with MCAS it still won't be equivalent to a MAX [sic] because it has MCAS."

I think he meant won't be equivalent to an NG....

And therein lies the issue which Boeing simply can't get around after years of trying.

So if there is no MCAS, would it mean that the MAX wouldn't be allowed to operate above a certain AoA? What would happen if the stall warnings all went off at the point the controls started going light? From previous descriptions it looks like this is a bit less than 10 degrees, with stall at around 15 degrees.

Is it possible to fly the plane safely?

And it's not just Boeing who are in trouble here as noted previously. Several large airlines have bet their hat on this plane and are now in big trouble if it doesn't come back.

If the root cause is a hardware issue, then the change needs to be hardware also. So two trim motors? Larger elevators? Taller landing gear to move the engine backwards.

I suspect it's just too late to do most of those, but that's still where it might end up.

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 5]

There are a few cases where we take the plane to near the stall on purpose and a couple when it does occur when its not meant to for some.

The main on purpose is a wind shear escape which is when the wind direction or strength or both changes virtually instantaneously. The momentum of the aircraft means it can take on the flying characteristics of a building brick.

The escape is to firewall the power which takes a few seconds to come online on big fan jets and pitch to the stick shaker, don't change the configuration, wings level and basically pray to which ever divinity is your preferred deity.

I have once in 16 years had to turn off the engine protection system Torque temp limiter (TTL) and basically accepted that I was going to destroy half a million worth of engines. Firewall with engine protection in limiting torque to 105% stick shaker going and still going down at 1500ft/min going through 700ft AGL. TTL system off engines giving 120% torque we escaped. Turns out I didn't destroy them You have to love Garrett engines, soap test every day for a week, then every week for a month and then give up. Lucky it was winter and the EGT was well below limits so no burnt turbine. Gear box was good for 150% torque apparently. If one of them had failed during it then we would have been dead with VMC rollover because there is no way the rudder had enough power at stall to control the aircraft one engine. Only way to escape VMC rollover is to reduce power on the live engine.

The main area where its likely to happen when it shouldn't is go-around. TOGA power and pitch up to climb, with less experienced pilots the engines take a while to spool up so they pitch to the go-around and then the engine pitch couple kicks in lifting the nose further. The pilot should compensate for this effect but it usually takes 2-3 sim sessions after qualifying on first jet type for it to become instinctive. I have this learning curve to look forward to when I move to jets.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

(OP)
Without a way to technically audit Mr. Marko's comments, I will put my confidence in them anyway, based on a number of other contacts I've had with him over the years. This is where I point out that I work in the aero engineering community in Canada, and interactions with Transport Canada are frequent - though not as frequent with the specialists in headquarters, like Mr. Marko. Having attended a couple of his presentations on the development and application of reliability guidebooks for systems analysis, I can't think of a more competent authority that I've met on the subject. As soon as the Max's were grounded, Mr. Marko became "unavailable" to all of us in the broader community as his attention became completely focused (among many others) on the Boeing issue. No matter how this turns out, I look forward to opportunities to hear Mr. Marko speak of his experience dealing with this problem. One of those "year of hell" stories that probably warrants a book deal.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Once again the Swiss cheese theory of holes has proven itself. I am sure readers may disagree on the weight of each factor, but when you line up these factors here (plus more of which I am yet unaware), the holes slowly line up. As usual, a series of poor choices is what lines them up. These are not in chronological order or order of importance, just a list for illustration.

The decision to use a critical flight control (stabilizer trim) for other than it's flight critical job of trimming the aircraft, but instead to divert it from its main task to a sub-task in a corner of the flight envelope.

Making the decision about using the trim because of a desire to NOT properly correct a fuselage design flaw with a fuselage correction (such as downward-angled strakes on the aft underside of the aircraft as one possible solution).

Believing that additional training in the flight characteristics was not required beyond a video, so as to avoid a market-limiting issue.

Tying the operation of a flight-critical control to a single sensor, with no cross-reference, no two out of three voting and not even any input smoothing to avoid the consequences of full scale spikes in the data stream.

Believing that the typical flight crew could notice, identify and correctly respond within 4 seconds to a system function failure that had never been practiced in a simulator.

Making all of the above poor choices, and then afterwards changing the control authority of the MCAS without re-addressing the issue with the FAA.

I recall reading years ago the book "On a Clear Day You Can See General Motors" by the now dead John Z. DeLorean. While he had his own share of flaws and foibles and I would not use him as either a managerial or lifestyle coach, I remember very clearly in his book his description of various high-level meetings about products. I am paraphrasing what I recall because I no longer have a copy of the book. As best as I recall, he concluded that a room full of smart, well-meaning people could collectively make a horrendous decision that not one of them would agree to or accept responsibility for if they alone were the decision-maker.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Apart from the issues with the 737 Maxx, I wonder what regulatory changes and design changes we will see in the future.
Given the correlation between fan diameter and efficiency the trend may be to ever increasing engine diameter.
We may anticipate more control challenges as engine sizes increase.
MCAS was designed to comply with the regulatory requirement that the control forces must increase proportionally.
While MCAS may comply with the letter of the regulation I seriously doubt that it complies with the original intent of the regulation.
May we anticipate the following regulatory changes?
Rewriting of the regulatory requirement that the unassisted control forces must increase proportionally so as to limit the amount of automatic correction of control forces.
A limit on the maximum allowable movement and authority of the stabilizer, so that stabilizer movement may be overcome by elevator movement.
A re-evaluation of the grandfathering criteria.
A limit on the allowable amount of mis-trim caused by engine upthrust at high angles of attack, by engine thrust, and by engine location.
Will we see a trend to rear mounted engines such as the 727?

Quote (Boeing web-site)

In September 1984, after a 22 year production run, the last 727 was delivered (a 727-200F to Federal Express). The once “very risky” 727 had become one of the greatest selling commercial jets in history.
I understand that larger engines were considered for the 727 but the issues with increasing the size of the center engine were economically unsolvable.
The third engine is no longer required for this class of aircraft.
I understand that mounting the engines in the plane of the center of gravity all but eliminates most engine induced trim issues.

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

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Not a bad list, but I think

"Believing that additional training in the flight characteristics was not required beyond a video, so as to avoid a market-limiting issue."

Really should be
"Having a primary design constraint that additional training would not be required beyond a video, so as to avoid a market-limiting issue."
Also

Changing the cut out switches so that manual electric trim could not be maintained alone,

Failing to add even a simple AoA disagree warning light (not that I think this would have made much of a difference, but it didn't help)

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 5]

waross,

I would hope that they pick up some of the issues identified by the NTSB with respect to overload of flight crew from multiple alarms and other issues caused by a single failure making it very difficult for the crew to determine the best course of action.

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 5]

LittleInch, all good points to my post. Thanks for the comments!

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Quote (LittleInch)

Failing to add even a simple AoA disagree warning light

If I've got this right, it wasn't they failed to add an AoA disagree warning light - they'd designed one in, but somehow failed to notice that it wasn't working on a majority of the jets they sold. Hard to blame that on groupthink.

A.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Failed in the sense that someone on the development team had a dot on their forehead to ensure that a design verification test would be performed.

TTFN (ta ta for now)
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RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Boeing experienced a fundamental change in company management culture beginning 20 years ago. I've been at smaller companies that had similar changes and the resulting impact in company culture. This recent article outlines the change at Boeing.

https://www.theatlantic.com/ideas/archive/2019/11/...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I'm always a bit leery of Atlantic articles. While it's possibly true that McDonnell Douglas management won out in the end, what's missing from this narrative is that Boeing was making that fundamental change on its own. The McDonnell Douglas management could not have risen to ascendancy without being bought out by Boeing in the first place. And note that Boeing bought not only McDonnell Douglas, but also Rockwell, so Boeing management was already pushing the company into a non-engineering structure by the very act of buying two large companies.

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RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I think there is also issues with rear mounted engines with uncontained disk failures and protecting the control runs after Soux I think the regs changed.

With rear mounted then they have to have a T tail which brings issues with a thing called super stall. When the aircraft stalls the vortex's off the wings then cover the elevator airflow so the elevator becomes ineffective for reducing angle of attack. I believe that the rear engine biz jets have such a huge power to weight ratio they can power out of it but that's into Sparweb's area of expertise.

Also you have issues with services and fuel lines as the fuel is normally around the same place as the centre of lift and C of G. Otherwise you get colossal trim changes between full and empty. Fuel is heated during flight and returned to the tank if this can't happen then the aircraft will have to fly lower which makes it less effecient. So you have two fuel pipes to the engines both capable of shifting tons per hour long fuselage and that a huge penalty in weight for armoured large bore high pressure fuel pipe.

Those are the reasons why they have gone pod underwing mounted engines in the last 40 years that I can think of off the top of my head, but I am sure there is loads more.

The high wing V low wing I am not so sure about. The BAe 146 wasn't a bad plane in fact those that flew it said it was pretty good for 5 hairdryers flying in formation with virtually a complete services spares back carried but called an APU (hence 5 hairdryers not 4 hairdryers in formation)

Anyway it seems the regulators are fighting back in the media battle with Boeing and re certification in December. Its good to hear from Sparweb that the person that sent that email is so well regarded and by the sound of it is an old school engineer and at that point in his career bullying will just not work and he will do what's morally right not what the Bean counters/politicians want. Quiet what would happen if they recertified it and there was a public announcement that regulator engineers world wide don't think it should be flying I really don't know. All it would take is 2-3 from each authority towards the end of their careers to make a statement and the 737-dodo will come into excisitance.

Just found this

https://theaircurrent.com/aviation-safety/boeing-7...

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

The RVI report is out today for the 738 crash during a windshear escape manoeuvre.

It has quite a few pics of various aircraft components including screwjack.

Also has a surprisingly high content about the cockpit environment.

It also has details about trimming forces on the 737 NG.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

^ Do you think there was an MCAS activation in the transition to climb out after the go around with the flaps coming up?

EDIT: Nevermind, not the same plane, not a MAX

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

As you say different aircraft so the speed trim system will have been running which is a common augment to both.

It was more for situations where the aircraft has to get to high alpha on purpose. In the situation in the above report the pilots would have had none linear control forces to deal with as well on a max no mcas.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

IRStuff - I too am leery of 'The Atlantic' as a news source. But as the Boeing 787 battery incidents, and later as the 737 Max incidents happened, I thought about what I had read and heard over the years about the internal culture changes at Boeing. For me the executive management move to Chicago away from all of the company operations evidence that the Boeing of old was gone. The Atlantic article has a good summary of what I have heard and gathered about Boeing over the years.

I experienced a 'reverse takeover' at a company I worked for. A couple high-up managers were hired from a failing corporation, who then made way for more of their buddies, and soon similar flawed management culture and decisions took hold and the company began to circle the drain. I left. Today that company exists only as a marketing brand-name-only owned by a foreign firm.

Then, I worked for an 25+ Mil engineering-oriented company. One that had 90% of it's niche high-end technical market and had dominated it for two decades. The company was bought by a large acquisition corporation who's focus was quarterly return-on-the-dollar. They brought in a lot of newly minted MBA's with no industry background. Within 4 years they had destroyed this company. Today, a core group of the original engineers who were 'downsized' as an annoying expense now work for a competitor who has taken about 60% of that niche market for themselves. The original company and it's brand name no longer exist, unless you go to eBay where their old products still have demand.

The Boeing of today is not the Boeing of yesterday. Maybe they can change and get their successful technical culture back. The technical culture is not the one at the engineering levels, but is one that has to start at the executive levels and permeate down from the top.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

How many MBA's work at the FAA?

They are also double digit percentage to blame for this thing having even one innocent clueless passengers bum in a max.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Having gone through the report this looks like a "manual" version of MCAS to me.

Twelve (12) seconds holding the trim button down and going negative G looks very much like the end of the ET plane where they went too fast and went negative G when they turned the trim back on and then MCAS kicked in.

I didn't realize that max power and a light plane with flaps down would require such a control column forward force (unless I've read this wrong) to prevent too fast a climb.

But an interesting thought process about the difference between the trim on a light aircraft versus a large commercial aircraft where the elevator trim is so much more powerful.

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 5]

Light aircraft accelerate fast.

When I say light it means the power to mass ratio is high.

Lift = 1/2 rho v^2 Cl area the elevator on the Ng is huge. So as you accelerate the stick forces change very rapidly.

The pitch couple of those powerful engines is also huge as they go from 40% Nr up to ToGa max chat power.

Some of us cheat and put a bit of power on pitch to the GA attitude start climbing and get the gear up and flap to climb flap, while doing this we trim the aircraft from approach trim to climb trim. Then we feed in the rest of the power. Unfortunately you can't do that with windshear escape. It all happens extremely fast.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

I've no doubt that the article represents some version of what happened, but like I say, I think Boeing was already on that road, having decided to expand by acquisition and to depend on subcontractors, which were financial and political decisions. They had instituted a plan to become a "system of systems" integrator, spreading development and manufacturing to subcontractors to garner political support and influence. Northrop Grumman and others became major suppliers of wing systems, etc., at least a decade before the purchase of McDonnell Douglas.

Boeing lost its way in other arenas, in any case; what happens at the top isn't necessarily impactful at the bottom. Their vaunted "world class" systems engineering was built on a premise that assumed that the "process" was everything, and that knowledge and experience was irrelevant. Boeing has failed miserably to manage programs such as FCS, because while they had the process, they had zero experience in ground systems, resulting in massive failures in requirements understanding, allocation, and flowdown. And again, since they depended heavily on subcontractors who had their own inertias and cost incentives.

Hiring people from failed endeavors, in of itself, isn't necessarily a bad thing. Ostensibly, someone from a failed operations has had the opportunity to learn from a bunch of mistakes. In some instances in Silicon Valley, people with failure experiences were actually highly sought after. We used to joke at another company and called ourselves "F- University," where you learn what not to do. The caveat, of course, is that there are thousands of ways to fail, but only a few ways to succeed; Edison supposedly said, "Results? Why, man, I have gotten lots of results! If I find 10,000 ways something won't work, I haven't failed. I am not discouraged, because every wrong attempt discarded is often a step forward...."

TTFN (ta ta for now)
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RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

Today's news is that the FAA have pulled Boeing's ability to issue cert of airworthiness certs and also export permits for the max.

Which basically means every MAX now has to be inspected by FAA personnel physically and also a paperwork audit carried out after Boeing has released it. Normally the OEM would release and issue paperwork using their own qa system during manufacture.it could easily triple the time taken to process the parked aircraft.

Second item is easa and uae have refused FAA certification of the 777x so Boeing will have to run two/three sets of certification paperwork.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

(OP)

Quote:

Today's news is that the FAA have pulled Boeing's ability to issue cert of airworthiness certs
That was always in the cards.

It's really surprising how deeply embedded Boeing has become in the FAA organization. Here's an "org-chart" for a branch of the FAA:

Looking carefully at all the offices listed, you'll see an array of FAA regional offices named - and one company.
Boeing actually has two FAA offices: the BASOO (top of the left column) and the Boeing CMO (second column).

I have very little moral high-ground to stand on. As a Canadian, I know just how overwhelming Bombardier has been with Transport Canada.
And nobody would be surprised if I accused EASA of doing Airbus's bidding sometimes.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

more than sometimes....with easa.

They are all at it. Just the FAA has been caught with there pants down with a sheep in front of them.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

That's a BAAAAAAAAAAAAD place to be.

RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]

With regards to the 737 NG, Boeing will be fined #3.9 million

Quote (Article)

Boeing knowingly submitted aircraft for final FAA airworthiness certification after determining that the parts could not be used due to a failed strength test.

In mind that kind of fine is an absolute joke. $3.9 million is a rounding error for a company like Boeing. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] The cost of late delivery penalties on the aircraft will have been more on 130 aircraft. RE: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5]$3.9 million is the rounding error on late penalties. Assuming the oft-quoted $5000/day penalty, they're in the$250 million range for penalties, although they may have made alternative arrangements.

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