Air India B787 crash Ahmedabad

[jb747]

Mary Schiavo was an ex lawyer with the U.S. Department of Transport who had a particular grudge against the U.S. FAA.

Well, she isn’t alone there.

Also thinks the 787 has FADEC when in fact it’s EEC so I don’t think her technical knowledge is statisfactory at all.

It is FADEC…. Anyway the two terms overlap. Full authority digital engine control, and electronic engine control. I doubt that you could buy an airliner now without FADEC.

People have locked in on TCMA, but I suspect that it isn’t the only thing that’s capable of shutting an engine down. Over-speed protection?

 

[RSD]

Well, she isn’t alone there.

It is FADEC…. Anyway the two terms overlap. Full authority digital engine control, and electronic engine control. I doubt that you could buy an airliner now without FADEC.

People have locked in on TCMA, but I suspect that it isn’t the only thing that’s capable of shutting an engine down. Over-speed protection?

Could be something really left field like computers erroneously received sensor signals that made the computers think that the plane was having an accident and so shut the fuel valves to try to prevent post-accident fire - because that is what it had been programmed to do. There is still the possibility too that the fuel valves were designed to shut if they lost power and that is what has happened - which caused the RAT to deploy.

Something has clearly gone very very wrong to lose both engines - and it doesn't seem to be the fault of the engines but something further upstream in the system.

 

[flyer89]

Mary Schiavo was an ex lawyer with the U.S. Department of Transport who had a particular grudge against the U.S. FAA. But most of her work was from the 90s. Now she supposedly works for a private law firm who seem very litigious.

Considered her an unserious person years ago when she claimed MH370 would’ve been prevented if all airliners had cameras in the coughpit.

 

[DC3]

…. be patient.

Should we guess what the likelihood of that is?

 

[Rabs97]

Well, she isn’t alone there.

It is FADEC…. Anyway the two terms overlap. Full authority digital engine control, and electronic engine control. I doubt that you could buy an airliner now without FADEC.

People have locked in on TCMA, but I suspect that it isn’t the only thing that’s capable of shutting an engine down. Over-speed protection?

Found a bootleg copy of the FCOM online,

For the TCMA to trigger the airplane needs to be on the ground, and the thrust lever at idle, and engine is above idle speed and not decelerating normally.

So one would deduce both the Air/Ground logic and the Thrust lever position signal on both engines would have had to be erroneous simultaneously for that to occur; has to be a billion to one chance.

Overspeed protection will command a shutoff, but it would be preceded by Thrust Limiting, reduced fuel flow first only then by fuel cutoff. And one would think after an authrottle failure too. The chances of all that happening simultaneously after liftoff?????

It’s a head scratcher for sure.

Could be something really left field like computers erroneously received sensor signals that made the computers think that the plane was having an accident and so shut the fuel valves to try to prevent post-accident fire - because that is what it had been programmed to do.

No such system exists.

 

[RSD]

No such system exists.

How sure can we be of that - given that Boeing never told anyone about MCAS until after the 737MAX had suffered two accidents.

 

[kangarooflyer88]

How sure can we be of that - given that Boeing never told anyone about MCAS until after the 737MAX had suffered two accidents.

I still maintain that there is a hidden reverse take off mode on the 787. Perhaps it was rarely triggered like one in a trillion and that’s why Boeing never disclosed it to pilots like they did with MCAS on the MD-737

 

[Rabs97]

I still maintain that there is a hidden reverse take off mode on the 787. Perhaps it was rarely triggered like one in a trillion and that’s why Boeing never disclosed it to pilots like they did with MCAS on the MD-737

Uh huh…..

Would you mind explaining how this “mode” works?

 

[kangarooflyer88]

Uh huh…..

Would you mind explaining how this “mode” works?

This is all speculation but when the mode is triggered the aircraft attempts to land by following the take off procedure in reverse.

 

[Rabs97]

This is all speculation but when the mode is triggered the aircraft attempts to land by following the take off procedure in reverse.

Uh huh……

Does it also announce to the pilots “I’m sorry Dave, I can’t let you do that……”

 

[RSD]

Uh huh……

Does it also announce to the pilots “I’m sorry Dave, I can’t let you do that……”

Well I did mention Hal about 20 or 30 posts ago...

 

[tgh]

the aircraft attempts to land by following the take off procedure in reverse

so I can understand reverse thrust but struggle with some of the basic physics in flying backwards… could you help me a little with this ?

 

[Rabs97]

the aircraft attempts to land by following the take off procedure in reverse

so I can understand reverse thrust but struggle with some of the basic physics in flying backwards… could you help me a little with this ?

I guess it’s like in Superman where he flies around the world so fast he reverses its rotation to reverse time and saves Lois.

 

[jb747]

For the TCMA to trigger the airplane needs to be on the ground, and the thrust lever at idle, and engine is above idle speed and not decelerating normally.

So one would deduce both the Air/Ground logic and the Thrust lever position signal on both engines would have had to be erroneous simultaneously for that to occur; has to be a billion to one chance.

The trouble with all of these aviation odds, is that they're generally just extrapolations of wishful thinking.

Interestingly, the takeoff seems (!) to be normal up until around the point that it gets airborne, i.e. where the ground/air logic changes states.

Overspeed protection will command a shutoff, but it would be preceded by Thrust Limiting, reduced fuel flow first only then by fuel cutoff. And one would think after an authrottle failure too. The chances of all that happening simultaneously after liftoff?????

Presumably, these are all just software subroutines, not actual pieces of hardware that do something specific.

 

[RSD]

Interestingly, the takeoff seems (!) to be normal up until around the point that it gets airborne, i.e. where the ground/air logic changes states.

That's one of the interesting things - if the engines were rolling back during the takeoff roll then it would seem unlikely that it would have gotten airborne, so whatever happened must have happened just after it got airborne and led to a very sudden complete loss of thrust.