Air India crash

[kgwilson]

2 hours ago, onetrack said:

 

As it is obvious from the preliminary report, the fuel cutoff switches were moved in the cockpit - and the crew voices confirm that.

As the PF is fully concentrating on the lift-off, and has both hands on the yoke, it seems it was the PNF who moved the switches. I think that the reason why he did so, may never be found.

As I understand it, the PNF is carrying out a purely monitoring job, so he has little reason to operate important flight controls - unless he saw an emergency.

But no pilot should ever take any drastic engine control measures at takeoff, 400 feet is the minimum critical altitude mentioned in all manufacturer and training information.

 

 

 

I don't think it is obvious at all that the cutoff switches were moved in the cockpit. That may just have been an assumption by the pilot when power was lost and the other pilot said he didn't. This assumes the 2nd pilot was not planning a crash.

 

The reports states 

at about 08:08:42 UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec. The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off. 

In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff. The other pilot responded that he did not do so.  

 

There are likely to be plenty of conspiracy theories going around but a software or system logic failure cannot be ruled out. If it was a system failure then over 1100 787s would be immediately grounded and that could put another nail in the Boeing & US Aviation industries coffin.

[facthunter]

Plenty of People and Pilot  and Regulatory Organisations watching this KG. The 787 is in widespread use and has a good record in service.  Nev

[kgwilson]

I agree. It is a superb aircraft. I flew in one from Sydney to Auckland some years ago. I am sure they are investigating the backgrounds of the pilots extremely thoroughly.

[Roundsounds]

39 minutes ago, kgwilson said:

I don't think it is obvious at all that the cutoff switches were moved in the cockpit. That may just have been an assumption by the pilot when power was lost and the other pilot said he didn't. This assumes the 2nd pilot was not planning a crash.

 

The reports states 

at about 08:08:42 UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec. The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off. 

In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff. The other pilot responded that he did not do so.  

 

There are likely to be plenty of conspiracy theories going around but a software or system logic failure cannot be ruled out. If it was a system failure then over 1100 787s would be immediately grounded and that could put another nail in the Boeing & US Aviation industries coffin.

What the “experts” on this site are missing is the fact engine systems operate independently. There is no way a software fault could cause both engines to fail within 1 second of each other. There is no doubt both fuel control switches were moved to cutoff, then 10 seconds or so later back to run.

What hasn’t been established is who did it and why. 

Edited yesterday at 05:04 AM by Roundsounds

[facthunter]

I just spent TIME on PPRuNe. I'm exhausted.  Nev

[skippydiesel]

1 hour ago, facthunter said:

Plenty of People and Pilot  and Regulatory Organisations watching this KG. The 787 is in widespread use and has a good record in service.  Nev

You would thinks so.

From very imperfect memory, there have been at least one known suicide by passenger laden aircraft - think European and several others where suicide suspected but not 😈

[danny_galaga]

4 hours ago, pmccarthy said:

I wonder whether a quick sharp blow, accidentally when removing hand from the throttles, could trip the two switches. Particularly if the detents were worn or somehow out of spec.

Juan Brown guessed that as well. That the switches weren't replaced under the AD that apparently was issued at some stage and that one of the pilots was 'guarding' the throttles and the plane jolted enough to make his smack down on them. Although that doesn't explain why they were switched roughly 1 second apart. 

[onetrack]

2 hours ago, danny_galaga said:

Juan Brown guessed that as well. That the switches weren't replaced under the AD that apparently was issued at some stage and that one of the pilots was 'guarding' the throttles and the plane jolted enough to make his smack down on them. Although that doesn't explain why they were switched roughly 1 second apart. 

The chances of an event like that happening are so remote, it's not worth considering. There were no "jolt" conditions on takeoff, and the other wild theories about a manual or iPad falling on the switches are equally fanciful.

No professional pilot in possession of an ATPL would have anything loose in the cockpit on takeoff - especially something that could fall on critical control levers or switches.

 

The switches were moved on purpose. Only further, deeper investigation may find the reason why.

 

The switches are a pretty standard Honeywell design that comes in huge variety of design choices and varieties. The part number is 4TL837-3D, and the spec sheet is in the link below.

 

The locking mechanism problem was found to originate in the locking collar becoming able to rotate, enough to misalign the locking collar notches with the projections on the switch body, and thus allowing the locking mechanism to be bypassed.

 

It appears Boeing decided it wasn't a serious enough problem on the 787, perhaps because the AD was issued, which made pilots and maintainers aware of what to check for.

 

I've been on a Virgin B737 flight that stopped on the taxiway and the crew called in an LAME to tighten the thrust levers mechanism, as it appeared the crew became wary of a potential thrust lever rollback, a common Boeing problem. 

 

So the crews are well aware of potential controls glitches and faults and I'm sure the pilot and co-pilot of Flight 171 were well aware of the AD relating to the fuel cutoff switches ability to bypass the locking arrangement.

 

https://datasheet.octopart.com/4TL837-3D-Honeywell-datasheet-31974395.pdf?_gl=1*1r8bggd*_gcl_au*NjIxNDk4MTU3LjE3NTIzMjQ2NDk.*_ga*MjA3MTA3MDU1LjE3NTIzMjQ2NDg.*_ga_SNYD338KXX*czE3NTI0MDU1ODkkbzIkZzAkdDE3NTI0MDU1ODkkajYwJGwwJGgw

 

Edited yesterday at 11:33 AM by onetrack
accidentally posted before I finished...

[Arron25]

I see the simulator Ex-spurts are sayings pilot error .. Are they The Same ones that vowed and declared Scully Could Have landed at an airport without a problem??

The blackbox is Only showing the electrical pulse in the wiring Not physical positions 

[onetrack]

10 minutes ago, Arron25 said:

The blackbox is Only showing the electrical pulse in the wiring Not physical positions 

But the electrical pulse is initiated by the closing of switch contacts, which can only happen with the physical movement of the switch mechanism?

 

I would like to see a description of what could cause an electrical pulse to the fuel valves, without any physical switch movement?

Then there's the description in the preliminary report that the fuel cutoff switches were moved back to RUN, and an attempt to relight the engines was made - which accordingly indicates the switches were initially placed in the OFF position?

 

Add to that, the report stating there were no reportable 787 issues identified, that needed to be communicated to Boeing? 

 

Edited yesterday at 12:35 PM by onetrack

[Arron25]

I believe I read the relight was induced by the FADEC not manually.

In an aircraft with documented existence of metal shavings in the wiring ducts and with no possible way to test the wiring for shorts in this instance.....

WHY are so many pilots so willing to throw these two under the bus?

Comes back to what I said earlier about Ex-Spurts.

There was as least one other unrequested shutdown, but as it happened after landing with no damage was undoubtedly not investigated thoroughly.

How many others were put done to 'just another unknown glitch' due to no damage?

[Thruster88]

I imagine that in the days from downloading the data from the flight and cockpit audio recorders on the 24th June until the release of the preliminary report on the 10th July the Indian investigation team would have asked many questions about how the fuel cut off system works and how the flight recorder gets information about that system.

 

The language used in the report indicates there was no doubt about what happened. 

[IBob]

57 minutes ago, Thruster88 said:

I imagine that in the days from downloading the data from the flight and cockpit audio recorders on the 24th June until the release of the preliminary report on the 10th July the Indian investigation team would have asked many questions about how the fuel cut off system works and how the flight recorder gets information about that system.

 

 

One would like to think so Thruster. But then we don't know what we don't know, and sometimes that means we don't know what to ask.

 

For instance, a lot of contributors here seem to be locked onto the idea that the FDR is directly monitoring those switches. That may be so, but it is also entirely possible that it is monitoring something in the logic that is 'looking at' those switches. In which case one has to look not only at the switches, but at that logic.

 

And, again for instance, nobody has thought to consider the approx 1 sec between the two switches being logged as off. Maybe that was so. But the FDR is accessing and logging a great deal of data, a bit at a time, presumably by repetitively scanning all the stuff it is supposed to pick up. That approx 1 sec could be due to the scanning rate, the difference between the time it looked at switch 1 then switch 2.

For me a major red flag in all this is that it took place at rotation. That, to me, remains an enormous 'coincidence'.

[facthunter]

I would suggest it is intentionally not easy to move 2 lock type switches at the same time. Richard De Crespigny's interview on the ABC this morning was good. Nev

[Roundsounds]

9 hours ago, Arron25 said:

I believe I read the relight was induced by the FADEC not manually.

In an aircraft with documented existence of metal shavings in the wiring ducts and with no possible way to test the wiring for shorts in this instance.....

WHY are so many pilots so willing to throw these two under the bus?

Comes back to what I said earlier about Ex-Spurts.

There was as least one other unrequested shutdown, but as it happened after landing with no damage was undoubtedly not investigated thoroughly.

How many others were put done to 'just another unknown glitch' due to no damage?

The only way to start a B787 is via the EEC Autostart function, you cannot complete a manual start in a B787. 
There is no doubt the FCS were moved to CUTOFF and subsequently returned to RUN. The only questions to be answered is who and why?

[Roundsounds]

50 minutes ago, facthunter said:

I would suggest it is intentionally not easy to move 2 lock type switches at the same time. Richard De Crespigny's interview on the ABC this morning was good. Nev

It can be done, just not a procedure. If both places to CUTOFF in sequence the delay of 1 sec is reasonable.

[facthunter]

You'd need to do it with BOTH hands.  Just WHY would you bother?  At low airspeed the engine Core will not spool up reliably unless engine starter assisted. Needs APU to be running.  Nev

[Roundsounds]

49 minutes ago, facthunter said:

You'd need to do it with BOTH hands.  Just WHY would you bother?  At low airspeed the engine Core will not spool up reliably unless engine starter assisted. Needs APU to be running.  Nev

In the event of a dual engine failure the B787 starts the APU without crew action, which the report says it had commenced. There must have been sufficient RPM for the start sequence as the Left engine had relit and was starting to spoil up again.

[IBob]

2 hours ago, Roundsounds said:

There is no doubt the FCS were moved to CUTOFF and subsequently returned to RUN. The only questions to be answered is who and why?

 

Certainly the information released to date indicates that, Roundsounds.
However, given the circumstances, I'm sure you would agree that all possibilities need to be investigated.

[BrendAn]

 

[facthunter]

It's been  clarified about the relight difficulties . Time needed and airspeed too low. The second motor wasn't making it. Core failed to get to sustainable RPM..  Nev

[Garfly]

There is an interesting interview on YT with Capt. Sam Thomas, President of ALPA (India) where he runs an argument against blaming the pilots at all.  It's a half-hour discussion but he makes a crucial point between 06:30 >> 08:00.  He reckons that cycling the fuel cutoff switches is actually part of the memory-items checklist in case of double engine failure and may just have been the captain's desperate attempt at a re-light when he lost both at take-off. 

 

https://www.youtube.com/watch?v=rJ_oNlBE_o8

 

 

 

Edited 9 hours ago by Garfly

[facthunter]

Emergency actions ARE memory items.  Time is the essence.  Nev

[Roundsounds]

25 minutes ago, Garfly said:

There is an interesting interview on YT with Capt. Sam Thomas, President of ALPA (India) where he runs an argument against blaming the pilots at all.  It's a half-hour discussion but he makes a crucial point between 06:30 >> 08:00.  He reckons that cycling the fuel cutoff switches is actually part of the memory-items checklist in case of double engine failure and may just have been the captain's desperate attempt at a re-light when he lost both at take-off. 

 

https://www.youtube.com/watch?v=rJ_oNlBE_o8

 

 

 

Cycling the FCS is a part of the dual eng failure memory items. The FCS weren’t cycled CUTOFF, then RUN, they were both moved to CUTOFF, then 10 plus secs later back to RUN. This not IAW the published memory items. 

[Garfly]

Yes, I gather Capt. Thomas' point was that the moving of those switches, at all, has wrongly been taken as incontrovertible evidence of foul play.  I, for one, am glad to see someone running his argument.  Time might tell.

 

 

 

 

Edited 8 hours ago by Garfly