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

This puzzled me as well and got me thinking about the quick diagnosis of the problem.

If one of the two pilots had preplanned this action, and didn\x92t want to be blamed for it, he will have known the conversation would be recorded, so he moves the switches to cut off, then immediately challenges the other pilot about the action, which of course he denies. One of them resets the switches to run, but by then it is too late.

Language:

Having lived in the Middle East for over 20 years, I am somewhat used to the Indian use of the English language. Therefore, I wouldn't look too closely at the usage of "transitioned"; it simply means moving from one condition to another.

The conversation of the pilots, on the other hand, will be very interesting. It should be analysed in the language they were speaking, considering whether this was their native language to start with. I assume that the conversation was in Hindi, translated to English for the report. In that case alone, a lot of nuance might have been lost in translation. That's without even considering the tone, volume etc. of the conversation.


Procedure:

I am an Airbus driver, so I am not familiar with the B787 EICAS. On the Bus, the ECAM would generate an ENG FAIL, followed shortly thereafter by an ENG ALL ENGINE FAILURE. I assume the B787 would have a similar event on the EICAS. Now, considering the time frame of how quickly things happened, there is absolutely no reason for the pilots to assume something was wrong with both engine cutoffs, unless they were physically switched off by someone. We are not trained to consider a fuel cutoff switch as the main reason for an engine failure, especially on the takeoff roll.


Question?

When I was a young F/O, some of the captains I flew with had the (annoying) habit of resting their hands just behind the thrust levers on their PM (PNF) sectors to 'be ready' to reject the takeoff. This would put the hands in the vicinity of the Fuel Cutoffs, which would, in turn, increase the chances of an unintended action on these switches. Is this a possibility, or am I way off?

Agreed: you would not see all contacts failing the same way, at the same time, in a multi-pole switch like that. Nothing is impossible, of course but the odds of that happening in one switch are extremely low. Two switches, at the same time?.
Ditto for the idea of the physical detents failing, causing the switch lever to drop at the worst time. Not impossible, again, but both switches within a second of each other? Very low odds.

Am I correct in thinking that engine cutoff would in flight would trigger a warning on EICAS?

It's established fact both fuel control switches moved to CUTOFF 4 seconds after Vr, a deliberate guarded action, not easily done accidentally.
The CVR records one pilot asking “Why did you cut off?”, the other replies “I didn’t”. Then a bland Mayday attributed to the Captain “engine failure, returning” in the middle of the crisis.

The language, if reported correctly, feels strangely detached. No confusion, no urgency, no clear troubleshooting. Not drawing conclusions, but does anyone else see signs of performative behaviour, that is saying the right things outwardly, while being at odds with the underlying cause?

I appreciate that both crew members lost their lives, however if we avoid discussing uncomfortable patterns, we miss the point of investigation and learning.

20 minutes between engine start and take off clearance. That\x92s enough time for the cockpit to cool down even if the packs were not turned on previously.

Really? It suggests to me and I would imagine the vast majority of us who have flown modern Boeings that they were physically moved, by one of the crew, one at a time, the question is why.

We can be sure this switches and their locking mechanism were carefully inspected in the wreckage .

since there is no grounding of the 787 fleet i think nobody considers the switches were defective but it seems to be clear for the investigators they were pulled and switched to cutoff by pilot action .

The investigation probably now concentrates by whom of them both and to find out if it was a catastrophic operation error in a mental blackout or a concious , deliberate action .

The accident aircraft was written up for a status message of ”STAB POS XDCR” on the previous flight, which is a message relating to implausible data from the stab trim switches. It was released from maintenance (according to the preliminary report) at 06:40UTC ahead of an 07:40UTC departure (the crash flight) with ”no fault found”.

On the 787-8, as all modern planes, switches are not cabled as dry closing contacts all the way from the switch poles to the affected end devices (FADECs in the case of fuel cutoff switches), but rather connect locally to an analogue/digital converter to encode the switch position data onto the digital comms bus ARINC629 which allows all aircraft systems to talk to one another.

Are the fuel cutoff switches, which are positioned adjacent to the stab trim switches, connected to the same ADC module which produced the error message on the previous flight, which maintenance was unable to resolve before the accident flight took off? I do not know, but it must be worthy of being looked into.

Previous media reports (from supposedly well-placed sources) talked about ‘voltage spikes’, ‘rapid power disruptions’, ‘faulty power-panel components’ and ‘EEC glitches’ inferring an uncommanded electronic state change in the fuel switches. This report sadly seems to reverse the causality.

The Mods have stuck to this principle, which I shall try to adhere to.
This preliminary report is just that, but maybe consider the issues the Indian AAIB have had to address in publishing it. They will have a similar concern to the pP mods, maybe more so since any apparent accusations directed at the pilots may lead to physical retribution.
I therefore conclude great care has been taken to "sanitise" what the AAIB know, or at least strongly suspect, (from EAFR) into the report. They have conspicuously failed to identify which of the pilots was each half of the conversation they have not repeated the exact words, there's a lot missing (was positive rate ever called, was rotate ever called, any discussion about putting FC back to Run, who/how flying aircraft meanwhile). As a result we, the reader, should step back and not over-interpret this sanitised report.

Secondly, given the mod statement above, if a criminal act is suspected by the AAIB, this will likely trigger all sorts of 'primacy' issues in the investigation i.e. police? AAIB? or joint? and all the history that involves (SAS Linate?) - in Europe we have 996-2010 Article 12 para 2, but India?

Summary : For good reason I believe this report has been very carefully worded, sanitised with great care, and as such easy to inappropriately speculate what went on.

From my reading of the AAIB report, the delay in noticing the cut off switch position could not have been any later than 08:08:47 because the reference to the verbal exchange was written before the reference to the RAT deployment and I assume the written narrative follows the chronological sequence of events. The delay in resetting those fuel switches might therefore have been no more than 5 seconds. It is a pity that the pilot making the challenge didn't simply reset the switches to run instead of challenging the other pilot. I frequently tell people who blow their horns at pedestrians or other motorists that blowing the horn isn't going to help them avoid an accident and that what they really need to do in the limited time available to them is concentrate on applying the brakes and turning the steering wheel.

Spoken to a rated mate whom is current on 78s and he told me that inadvertent operation of a fuel shut off in flight has happened with a switch being knocked past its detent (lock) by the switch being caught by a crew bag.

Probably not during Takeoff I wouldn\x92t have thought.

I cannot imagine a situation where any pilot would be moving a crew bag within seconds of getting airborne.

From the report it is clear that the switches were selected to cut off, we will likely NEVER know why, maybe the CVR gives a few more clues but we will never know if it was an intentional or accidental act. What is clear is that during rotation you are never fiddling with bags etc.

Was the RAT deployed manually?
The report says, This was 5 seconds after the fuel was cut off.

It suggests to me that the RAT deployment was initiated while the engines were still above idle and generating electrical power. Obviously one of the pilots could have done it via depressing the switch, as it's a "dual engine failure/stall" memory item (see Air India Ahmedabad accident 12th June 2025 Part 2 ) that won't hurt anything.

Is there a way for the RAT to deploy while the engines are still above idle?

Honeywell Switch Gate Configurations (Ref: honeywell_hwscs06627_1-1735572)

This extract from the datasheet of the Honeywell switch installed in the B787 for switching between Cut Off and Run shows the various gates that can be incorporated in such a switch. I suspect that it is Configuration D which allows the switch to be in one or other of only 2 positions. But the centre gate has a relatively wide flat table on which the switch can rest if it is not moved correctly to either the Run or Cut Off position. I therefore think that it is not beyond the realm of possibility that both switches may have initially been resting on the gate and then slipped into the cut off position during take off. However, what militates against this theory are the words of the challenge, "Why did you do that?" suggesting that one pilot had seen the other pilot actually flip the switches.

Good question as the report says FAA advisory NM-18-33 (check for potential fuel cut-off switches fault) was not implemented by Air India.

That seems to me to be a very feasible possibility. Noticing, then accidentally hittting the wrong thing in a quick reaction, especially during a possibly bumpy take-off, then only realsing as power starts to die away... A very simple human error possibility - and the switch location makes it horribly easy, especially ofthe switch locking is dubious. Ergonomics and human factors in design? In a very different environment many years ago I was involved in investigating somethimg rather similar (though not deadly). Taught me a lot about operational human factors and our design assumptions...

It's possible, damn it. How dreadful if correct.

That is also a worrying place to put vital switches. Handy place to rest your arm. I have one person I fly with who tends to rest his hand right on the flap lever (light aircraft) if he is not handling the aircraft. I really don't like that. It's bit like my current car, which has the handbrake 'switch'(!) on the central console, behind the gear lever. Just right for accidental operation - and it has been done.

Well, speaking of fuel-cut switches, I read NM-18-33 SAIB with attention, and as a not-that-fluent english speaker, I stumbled on this sentence (my bold):

I could hardly figure what the "disengaged" word meant in this context, so I did a Google search for the switch part numbers (especially "766AT614-3D") to figure the difference between them, and a page from this chinese web site was part of the results.

And while I was painfully crawling the thread, I noticed the following picture about an "undesirable condition":

Incorrect lock tab position on fuel cut-off switch

If this incorrect mounting is actually possible, it would possibly remain unnoticed from the pilots (normal "pull-up then move" action is unaffected), but it would cancel the protective function of the so-called "locking tab", and even limit the travel of the switch handle in both directions, making it more vulnerable to an undesired change of state.

The photos above seem convincing enough, but I'd be very grateful for an informed opinion on this assembly mistake. Even if this is possible, the probability of both switches being unexpectedly snapped seems very remote to say the least, but not as remote as previously estimated.