Air India 787 crashes on take off 2

[LittleInch]

A full 787-8 has crashed shortly after take off in ahmedabad.

Basically barely got off the ground then look like its trying to land in this video.

Air India flight to London Gatwick crashes in Ahmedabad with more than 240 people onboard – latest updates

Plane for flight AI171 was carrying 242 people including 169 Indians and 53 Britons, says Air India

www.theguardian.com

Specualtion that they pulled flaps up instead of gear up and basically didn't have enough lift so it looks like a gentle stall right into a built up area.

Looks to be flaps up, slats/ nose flaps down and gear down which is very odd.

 

[LittleInch]

I've been on that page for a while now as well.

 

[Garbage1]

I have read default position for Fuel Shutoff Valves (FSOVs) is the off position. Therefore complete loss of electrical power automatically shuts fuel off to both engines (perhaps spring loaded to auto close) RAT would take some time (say couple seconds) to deploy and provide power after deploying, and engines already shut down with no altitude/time to start back up.

They went on to say Airbus has battery backup power for fuel valves, but not 787.

 

[LittleInch]

But what was the Original failure?

Ï I've seen that the badly burnt front unit was henning sent to NTSB in the UD as this might have data after the assumed dual engine shutdown.

 

[Garbage1]

But what was the Original failure?

Ï I've seen that the badly burnt front unit was henning sent to NTSB in the UD as this might have data after the assumed dual engine shutdown.

Don't know, perhaps once Captain Steve gets past his latest video on "Vapor Lock" we will find out........


In reading the following, u would expect main battery to be first backup to electical power loss, and you would think backup design would keep fuel valves open. Now did main battery also fail or did electrical failure take it out of loop?


The 787 Dreamliner has two primary rechargeable batteries – the main and auxiliary power unit (APU). While identical part numbers, they serve separate purposes.

The main battery “powers up” aircraft systems, bringing the airplane to life before the engines have been started. Once the engines are started, the electrical energy to run the systems comes from generators. It also is used to support ground operations such as refueling and powering the braking system when the airplane is towed. The main battery also provides backup power for critical systems during flight in the extremely unlikely event of a power failure. It is located in the forward electronics equipment (EE) bay, which is under the main cabin floor at the front of the airplane.

The APU battery supplies power to start the APU, which in turn can start the airplane engines. The APU, and its battery, also serves as part of the multiple layers of redundancy that would ensure power in the rare possibility of a loss of primary sources of power.

 

[TugboatEng]

I wonder what the replacement interval is for the batteries? The airframe age is right around the life expectancy of a lithium ion battery.

What is the response to a fire in the after electrical equipment bay?

 

[Alistair_Heaton]

Response is getting on ground asap.

Here is my valves which are open all the time normally.

 

[Garbage1]

Response is getting on ground asap.

Here is my valves which are open all the time normally.

What response is getting on ground ASAP?

A legend would be helpful with the picture of the specific unknown airframe simulation, for folks without a pilot's license.......

I have added arrows to where I think you are referring to fuel shutoff valves for engines. No idea what some of the other symbols mean, or why there is green high-light is around the fuel tanks and the path to APU? While paths are white to engines?

 

[Alistair_Heaton]

Sorry was taken on phone at work.

It's an A220 on stand with the apu running just finished fueling to 7 tons

Engines are white because they are not running APU is green because it is. Green pipe means fuel flow. The green arrows mean fuel is going from the centre tank to the wing tanks.

The valves are white below the check box which indicates the fuel filters.

The response was about a fire in the avionics bay or electrical bay. We don't have a fire detector in there or fire suppression. It's part of the smoke emergency checklist which you progressively isolate different buses until the smoke clears. But it's a land immediately emergency checklist. ETOPs certified like the 787 may require to have a suppression system.

The emergency battery buses we can't see on a status page unless there is a problem.

 

[Garbage1]

Thanks for the back ground information. You and Tug both bring up another possibility of a battery fire causing a power shut down process to start, whether automated or manual, and it is possible that shut down process could have caused momentary loss of power to fuel shutoff valves? If the fire source was due to a lithium ion battery short, then battery backup power is not available to handle transition from engine power generation to APU and/or RAT.

 

[Alistair_Heaton]

I find it a bit strange that power is required to keep the valves open. Ie they are failed closed.

A220 it's a motor. No power it stays where it is.

 

[Garbage1]

I agree a two way actuator that stays in current position makes more sense, but in a fire situation which might involve loss of power, having it auto close might make some sense? Probably not, especially with all the backup power options provided, if they are all properly maintained and battery performance monitored and replaced well before loss of significant capacity. I for one test my auto batteries and replace when CCA capacity drops around 20-25% below rated capacity for OEM sized batteries.

I found this Boeing Battery Fire Guide for Fire Fighters, for those interested.

https://www.boeing.com/content/dam/boeing/boeingdotcom/commercial/airports/faqs/787batteryprocedures.pdf

 

[TugboatEng]

That's quite the containment system for the battery. I wonder how much weight savings is achieved vs ni-cad if you include the containment shell.

The bulletin mentions rupture disks and exhaust ports. There isn't any obvious smoke in the videos.

 

[Alistair_Heaton]

I think they only realised that after the 787 was grounded due battery fires.

There are tubes for various things to outside the skin with a blow out disk to release.

There was a biz jet in Marshalls in Cambridge for over 3 months getting decontaminated after a battery fire. They said it was 12 blokes a day working in shifts of 2 hours in suits the whole thing was in a filtered tent. I don't know what type of battery it was.

 

[TugboatEng]

In the maritime industry we have "low smoke" electrical cable. I don't know that it makes less smoke but the insulation is halogen free. Otherwise, we use PVC jacketed wire everywhere low smoke is not required. After a fire any halogenated compounds that burn produce acid gasses which may require cleanup.

Funny that an aircraft for the wealthy requires 3 months of decontamination but strawberries and brussel sprouts next to the Vistra battery plant fire required no additional scrutiny prior to sale for consumption.

 

[Alistair_Heaton]

This was around 2004.

Now we are into the use of kapton wiring in aircraft. Which I have no clue what's used in the 787.

Btw pilots receive zero training about this certification stuff on fire. The mil test pilot trained will know. I personally don't. Choose you social media experts looking at the background.

There is some bizarre theory's out there that just seem to run. Like the vapour lock occuring simultaneously on two engines after they have been running for 15 mins and been at takeoff thrust for 60 seconds.

 

[TugboatEng]

I thought there was a move away from Kapton wiring after the TWA 800 explosion. The insulation is too thin and doesn't tolerate mechanical wear.

The marine industry uses cross-linked polyolefin insulation. It's good stuff. I see little deterioration after 30-50 years. The PVC cables are pretty stiff at that point. IEEE 1580 covers our cabling standards if anyone is interested.

I never much understood the concept of vapor lock. If it were a real phenomenon one would think it would apply universally across a type of vehicle. None of my carbureted vehicles ever experienced vapor lock. I do believe some people don't recognize or know how to clear a flooded engine.

In my Z-drive fleet, my Rolls Royce drives want 24 bar to lift the clutch relief valve. After an oil change sometimes there is enough air in the system to keep the pump from making 24 bar and the system stalls. This isn't a vapor lock but may be interpreted as one.

 

[Garbage1]

I never much understood the concept of vapor lock. If it were a real phenomenon one would think it would apply universally across a type of vehicle. None of my carbureted vehicles ever experienced vapor lock. I do believe some people don't recognize or know how to clear a flooded engine.

Vapor Lock used to be a real thing in very hot climates, prior to fuel injection and electric fuel pumps. I have experienced it many times with 100% gasoline, and with 10% corn. Ethanol has lower vaporization temperature. One case was marine carb with diaphram - fuel pump inside, while the other was V8 offroading with block mounted diaphram fuel pump and Holley Carb. Vapor lock occurred in both cases after shutting down engine and trying to restart before under hood temps dropped. Cured problem on Jeep by installing electric fuel pump just outside fuel tank.

Now back in the high octane days, I never remember experiencing it with 1960 or 1970 OEM auto daily drivers that had carbs with mechanical block mounted diaphram fuel pumps. The Jeep engine was rebuilt with performance modes and headers which generate more under hood heat, and slow pace of trail on very hot sunny day heats things up a lot.

All that said, no way AI 171 was experiencing vapor lock as stated by Ali.....

 

[TugboatEng]

I have to ask the question but how do you know you weren't flooded? That would also resolve itself as the engine cooled off.

If vapor lock were real it should be endemic to specific vehicles or pandemic to the entire automotive industry and it isn't. Instead some older vehicles experience driveability issues on but days. This reads as a wear issue.

 

[Alistair_Heaton]

Kapton wiring seems to be in the same league as Thalidomide as a drug in aircraft.

But I will let people that actually know the real deal with it answer.

It's way way more common than you think. Both Airbus and Boeing still use it.

 

[LionelHutz]

Vapor lock was the dumbest theory I've heard so far.

The 787 flight software tries to correct for yaw on single engine failure. So, a single engine failing before lift off might not cause an obvious yaw. A theory that would make more sense was an engine failed somewhere around the V1 point and then as they began lifting off they then turned off the wrong fuel cutoff.