Air India 787 crashes on take off 1

[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.

 

[Alistair_Heaton]

It definitely doesn't solely, its one of these triple redundancy systems for FBW.

Although quite how it works I have no clue. I am actually hoping that someone that does, is going to show up and explain.

 

[TugboatEng]

I can't believe the FADEC takes 3 separate throttle inputs simultaneously and votes on them like other critical sensors such as air speed or AoA.

 

[Alistair_Heaton]

They are digital inputs. And there is a voting system which then links to the EICAS.

Its called the EEC (electronic engine control).

Which we have 2 channels per engine with a 3rd emergency. And if 2 go leaving only the emergency the other engine can support the other with its spare. You can still depart with 1 channel down gives an engine redundancy loss I think. Its a B MEL item 3 days to fix I think . If you get down to emergency channels in use its land at nearest suitable I think. Haven't checked the manuals so maybe incorrect. Its all in a EICAS checklist.

This is the problem with running multiple MEL failures there is no way all the combinations can be predicted and the interactions and response on the software.

What's in the lever quadrant in the 787 I really don't know.

This was the problem with the A220 dual engine shut down on landing .

We don't need to know how it works. Or what has a vote in things.

“A subsequent investigation determined that the sequence of the auto-throttle increasing throttle to maintain Mach number, immediately followed by pilot command to decrease throttle to idle, caused a transient disagreement between actual and commanded thrust. This disagreement triggered the thrust control malfunction (TCM) detection logic and resulted in dual engine shutdown once the weight on wheels signal was activated upon landing”, the FAA AD says.

It adds: “The installed EEC Full Authority Digital Engine Control (FADEC) software version latches the fault and allows the engine to continue operation as commanded but shuts down the engine upon landing.”

The FAA notes that P&W has identified the situation that could trigger a fault in the TCM logic and has come up with a software update. “This software update makes corrective improvements to the TCM logic, including revised criteria for triggering the TCM logic and establishing criteria that permit the TCM logic to unlatch during flight.”

 

[1503-44]

I have run videos above, the one with AI flight passing above to the left and another one I found of a flying 787 with with the RAT deployed, for testing purposes, through a sound analysis app called Spectroid. Spectroid makes a waterfall plot of all frequencies and amplitude. I think I see similarities.I believe the RAT WAS DEPLOYED.

As I mentioned previously, the 14 seconds up and 14 seconds down would point to a highly kinetic launch. I'm going with power loss within seconds after, or even before liftoff.

 

[1503-44]

I just saw that Captain Steve's latest video has amended his opinion to the same.

 

[Alistair_Heaton]

Can people keep an eye out for anything to do with the hydraulic isolation valve.

There are 2 valves away the engine which stop fuel and hydraulic fluid going past the fire wall each side.

That valve which is used in the event of engine fire is my prime suspect for the one that shuts down the engine so quickly. If both it and the hydraulic valves are shut then it's a emergency shutdown trigger.

Don't ask me how that works I just know it's different from the normal shutdown sequence.