Posts about: "Fuel Cutoff Switches" [Posts: 802 Pages: 41]

I was thinking about this scenario when PF with the HUD down. The fuel switches are not in my field of view, so if you weren\x92t expecting it (and you wouldn\x92t be), a complete loss of thrust at v2 would come as a surprise to you as there are no engine indications on the HUD. I am not sure the PF would look down at the fuel switches in this situation, maybe at the EICAS but likely you will be busy flying the aircraft and leave the troubleshooting to the PM.

So if it were deliberate by the PM, the PF would be very slow to identify the problem. Unless you saw it happen (very unlikely), it would be virtually unrecoverable.

Just to clarify, I'm not aware of any confirmation at this point that the Fuel Cutoff switches were physically moved from RUN to CUTOFF and back again.
We do have evidence that the FDR, thus the databus, received signals that the Fuel Cutoff switches were in the RUN position, then the signals changed to CUTOFF one second apart, and then back to RUN at four second intervals.
In the absence of video, we could only use CVR data to determine that the switches were physically moved - either through flight crew conversation or sound of switches being moved.
When the PF asks why the PNF "Why did you cut off" we don't know whether he concluded the fuel was cutoff by checking the physical position of the switches or through instrument annunciations.
I accept that with sampling rates the physical movement of switches to CUTOFF at one second intervals could be logically explained. I can understand why there would be such an interval between physically moving the two switches back to RUN, unless there was some sort of struggle which presumably would be easily detectable on CVR.
Unless I've missed something, I'm not ready to conclude that the switches ever physically moved.

Looking at some past FDR data, it appears that the fuel cutoff switches are sampled at 1 Hz, but the actual valve position is sampled at 4 Hz. The position of the fire switch (fire handle) is also recorded. N1 and N2 are sampled at 1 Hz.

That's interesting and potentially tightens the time window a little (if one presumes that the valve position is a proxy of switch position, which in this case there's no reason to believe otherwise, and if the prelim uses this info to feed it's timestamps which I'd loosely assume it probably does...).

He's talking about a 10 sec delay between fuel cutoff and back to run (after 4min15sec into the video)

Look at 5.06 in the video, he simulates the CVR comments immediately after the cutoff and times the gap until they are switched back on. He may be right, but that timeline has no more validity than the CVR comments being 1 second before the switches are turned back on again, which could paint a very different picture (inadvertent or mechanical).

I don't think a ten second gap between event and recovery action is particularly noteworthy in terms of demonstrating malfeasance.

Bear in mind that it would take 1 to 2 seconds for this to have become fully apparent, plus then initial surprise to figure out it was engine related - being optimistic, 3 seconds total.

7 seconds does not seem remotely unreasonable to then deduce cause, especially given what various other posters have said that FC switches wouldn't be high on their list to check. In fact, it seems like pretty good going.

If it was 10 seconds between the CVR and recovery action (as per your quoted poster) then that changes things quite a bit. But it wasn't.

PS the conclusion may be right (or it may not be), I'm open on the topic. But that 10 seconds gap doesn't tell us the answer.

Ok, agreed. we can't know when these words were said, but I think it's reasonable to assume it was somewhere in the 10 sec gap.
The point he's trying to make is that this 10 sec delay is consistent with his assumption that it was all premeditated by the captain.

Yes, that is clearly what he is trying to make. The point I make is this: that point rests almost entirely on the CVR conversation happening very shortly after the switches are activated and there being a long pregnant pause before they are switched back. Had the cutoff been inadvertent (mistaken action by PM or mechanical) and it took them 8 seconds to work it out (which is quite reasonable under the circumstances), the switching of them back on 2 seconds later could equally be an entirely consistent timeline.

The report has not identified who said those words and when. I find this curious as it's pretty easy to count back the seconds from the end of the CVR recording or forward the application of full power.

Great comment by GroundedSpanner in post 561 Preliminary Air India crash report published
The switches act on multiple circuits. A single electrical / electromechanical fault shutting down both engines is Extremely Improbable.
A few more observations on switch comments in this thread:
Liquid spillage - Switches are sealed so highly unlikely and not both at once.
Switches between detents \x96 The surface the locking \x93pips\x94 sit on is slightly curved. You can get the switch to sit on it but only with difficulty. I can see no way how both could be in this position accidentally.
Naming \x96 These are normally called a \x93locking toggle switch\x94.
It is a difficult design problem. You have to have a means to shut off the fuel but a single fault should not shut the off OR stop you shutting it off.
(I design fuel control systems for CS 25 aircraft).

As reported yesterday by the FT

The US Federal Aviation Administration has issued a notice to its international counterparts that fuel control switches in Boeing aeroplanes like the Dreamliner involved in last month\x92s fatal Air India crash do not pose a safety issue.

The FAA\x92s notice to foreign civil aviation authorities followed a preliminary report by India\x92s Aircraft Accident Investigation Bureau that the engines on Air India Flight 171 briefly cut off shortly after take-off on June 12.

Two separate fuel switches set to cut off, at one of the most critical phases of flight where doing so would lead to an unrecoverable situation, followed by one pilot asking the other why he set the switches to cut off.

No AD from Boeing or NTSB.

Come on.

Given that there's no evidence that the Fuel Cut-off Switches, or indeed any other part of the aircraft functioned incorrectly, what exactly should such an Airworthiness Directive be saying?

I might be wrong but I imagine the OP is referring to the elephant in the room.

Once in a bazillion, eh?

It seems more passengers are dying in scheduled flights in recent times due to pilot suicide than any other cause - and people still want to argue about whether it was suicide or an accident after the fact.

The simple fact is it would likely have 'solved' this accident by now. We'd know if the fuel switches were operated by a crewmember. We'd know which crew member. We'd know who asked who "why'd you [go to] cutoff?", we'd know if there was any physical activity between the two before or after the engine shutdown and we'd (probably) know if there was any indication or external reason for them to do so that isn't captured on the DFDR or CVR. The ATSB raved about the ability to recover video footage in the R66 prang - and that was a single-pilot helicopter that was fitted with it, one could only speculate how much the accident investigators would have liked to have it here...

So...I ask this as a genuine question - why are pilots so fearful of being video'd at work when virtually every other industry - particularly transport related industries - has at least CCTV, if not more intrusive methods of surveilling their employees? In my last company, we had real-time In Vehicle Monitoring Systems , Dashcam's and Cat Driver Safety Systems in our light vehicles, FFCCTV and dataloggers and IR detectors in the locomotive cabin to detect movement, CCTV throughout the shunting yard and car dumpers as well as the datalogging of the signal system and radio communications - and that was just a train company. And the notable thing about all this surveillance is, several times, I was able to demand the relevant evidence be downloaded and it cleared me of an allegation of wrongdoing. In part, due to the lack of protections afforded us in rail when compared to the legislation guarding use and disclosure of the CVR that exists in aviation.

Can anyone articulate a specific reason or their grounds for not wanting CCTV in the flight deck - and not just a catchall "it's a hostile work environment" - what makes it hostile in your view? Why do you feel it's acceptable to be filmed in the aerobridge but not the flight deck? The fact they can watch you screwup instead of just listening to you screwup? The fact you can't hide anything that goes on behind the closed door after an accident? What specific articulatable reasons do pilots have for not wanting to be captured on CCTV in their workplace like so many other employees around the world take for granted every day?

One engine started to accelerate from the minimum speed reached. While that may have reduced drag very slightly I doubt it changed the impact point of the aircraft more than a few meters. The time from cutoff to run on the number 1 engine was 19 seconds before impact.

Pilot error.. flown 777 and 787 for years now, these fuel control switches don't bounce about and it takes a positive action to move them to cut off.. FO was PF and Captain probably got confused by throttles rolling back and started double loss of thrust memory actions... but at low altitude? what on earth ? Thrust levers were "fully forward " according to report so some attempt to squeeze the juice... of course if it was something more sinister with no audio on the CVR we will never know.. sadly

I think there's a good chance that there might be mandated CCTV in cockpits in the future as a consequence of this accident. There's also near enough to a 100% chance it would not and could not prevent this type of accident, but "accident prevention" will be the reason given. It always makes me curious how knee-jerk regulatory actions get justified. I don't care that much if they do install it - the worst that could happen is I get sprung picking my nose. But I do care when authorities or Governments issue nonsense reasons for it in an effort to be "seen to be doing something" by the public.

I'm late to the party here (deliberately) but I'm slightly surprised there seem to be quite a few commenters not acknowledging the elephant in the room after this report. I spent years on the B767 and the B744 before moving to Airbus. These are big chunky switches requiring two different muscle actions to change their position. "Accidentally" moving them from run to cutoff with a neat 1 second split is extremely improbable even at the best of times, and makes no sense at all during the first moments of the takeoff phase. The hypothesis which does make more sense based on the facts now available is just a bit disturbing to mention, but that's unfortunately where we are at the moment.

Even if the engine would have accelerated to TOGA - no way to fly you out of that situation being near stall speed far below Vmca, with no altitude to trade for speed on one engine.

I have flown as a copilot with Indian captains, and as a captain with Indian copilots. I have no negative comments about Indian pilots, and \xabauthority gradient\xbb was not an issue.
The fuel switches will not move by themselves. Electrical gremlins will not change the switch position. One pilot asked the other why he moved the switch(es). It was done manually.

So WHO and WHY is the question. That leads further to done with intent or done without intent.

We can safely say that at the moment, WE DON’T KNOW.

This is not a competition.