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

Incorrect Locking
The spring function is still active, but due to the displaced locking ring, the tab does not engage with the detent.
The two conditions for the switch remain unaltered - Cutoff / Run, but the Run position is not gated, held in position.

Edit; "Can these switches be carelessly set in the on position but not fully locked? I am thinking whether it is possible for the switches to be electrically on, but not mechanically locked."
Yes

The bottom section of either switch can be clearly seen in this post accident photograph. There is nothing visible where your theory would require a well visible detent.

Either the inclusion of the Boeing SAIB was a red herring or they know something about the switches. They took a low resolution photo, page 10, Fig. 13. I can't discern dogs or bosses on the left switch bottom body.

Boeing's whole differentiation from Airbus in design is they want the pilots to have more control. Also this would never pass certification muster. Adding more automation doesnt always make things safer, lots of unintended consequences. At some point you just have to accept when you fly your life is in the pilots hands for good or bad.

But how many 787s switches have actually been inspected?
It was stated that Air India didn't bother to do so, as the directive or whatever it's called, was not mandatory.
I'm not trying to point the finger at Air India, or suggest that these switches could be faulty, rather highlight how the industry can be seen to function.
There have been numerous accidents that could have been prevented, if remedial actions had not been allowed to be deferred.

Oh yes the classic, rotation caused these locked switches to transition to cut off but flying into a building wasn't enough force to have them do the same movement.

Apologies for the delay in responding to your point, but as I explained previously, the preliminary report was almost certainly written to place on record everything pertinent that is known. If something wasn't included in it, then it either isn't known, or more likely at this stage, was not considered to be pertinent.

Given that we do not know what evidence there is, even as there is certain to be more to gather, some of us can happily speculate, though not with any authority. But this would basically tell us that if the investigators know who said what, that at this stage, in the context of what THEY know rather than we do, it wasn't pertinent to report that detail.

And really, in preliminary report terms, where the objective at this stage is to lay out WHAT happened, the question of who said what, when it would seem to be a single question and a single answer, isn't relevant in laying down the pertinent facts. That is unless (and until) there is reason to suspect a deliberate or actionable act by a member of the crew. There appears not to be any evidence of mental or physical health impairments which would lead that way at present and point towards the WHY, so no purpose in diverting their and our attention as yet from the WHAT.

I say this as someone who has done this kind of investigatory work, and authored reports from it, knowing that there is sometimes considerable tension between the need to investigate and be thorough and precise, and the public interest which reasonably demands and should have answers.

The switches in the photo are of a Boeing 737. The crashed airplane was a B787. It has a different type of switch. May look from the outside the same as a B737 switch. Partnumber is different.
Also Air India did not find any faulty switches.

https://www.reuters.com/business/aer...es-2025-07-16/

The discussion on faulty switches is a red herring. One of the pilots moved the switches. Either deliberately or by mistake.

There is a CMR on the 787 to remove and do an inspection of the thrust lever mechanisms on a periodic basis - I don't know (or at least remember) the interval, but I'd expect it to be in the 20,000-30,000 hr. range.
This is related to the FAA preoccupation with Uncontrollable High Thrust and the potential for a mechanical failure in the thrust lever mechanism to cause UHT.

As previously explained, the fuel control switches are a 'break before make' design - with a nominal gap between the two states of about 50ms.

Dani, the reason your posts regarding nearly simultaneous switch failures keep getting deleted is that this exact scenario has been repeatedly raised in the three Air India accident threads - and then thoroughly discounted and dismissed by people who - unlike you - are actual experts on the subject and/or pilots who have regularly used them. That your latest attempt to resurrect this hugely improbable scenario has remained and resulted in another 4 or 5 pages of hamster wheel discussion suggests to me that the mods have simply given up on this thread...

Can someone please confirm whether or not the respective fuel cut-off switch is directly connected to the open/closing coils of the fuel valve actuator? Or is there some intermediate control system between the switch and valve actuator?

Something else that has been repeatedly discussed in the three threads...
While there are interposing relays, the signals to the Fuel Metering Unit shutoff valve and the Spar Valve are hardwired from the switches to the valves in question. They don't go through some computer interface that could corrupt the signals.

From earlier and from the Honeywell datasheet these are 4PDT switches with all 4 section having the center as a common (ground AFAIK ) so that the FDR and other circuits can positively see that the switch is on one condition or the other--except for the brief time that both are open during switching. Snap toggles like this are most commonly break-before-make as tdracer confirms (but 50ms seems like a long time...). What this means practically is that a break or short in the wiring would cause a fault that would be recognized as such since a correctly operating circuit will have one or the other but not both of the circuits completed and there are 4 sets of circuits.

The recorded switch position data, the recorded engine performance data, the aircraft performance and trajectory after take off, the RAT deployment and open/ing APU inlet, the cockpit voice recording that has been selectively and carefully paraphrased in the preliminary report and the physical and electrical design and separation of the switches and the wiring for each system prove, to whatever standard of proof anyone wants to nominate, that BOTH fuel cut off switches were physically switched OFF 'shortly' after take off, then BOTH switches were physically switched back ON 'shortly' thereafter.

Give the FSC switch/wiring defect theory away, hamsters.

tdracer excellently summarised. But I'll confirm.
The switch is directly connected to the coils of a latching relay. That latching relay is directly connected to the coils of the spar valve. There is no digital logic device in the way,
The position of the switch is monitored (through a different set of contacts) by the EAFR (twice). The position of the spar valve is monitored by the EAFR.
Thus the recorder sees (twice) that the switch is moved, and that the valve moved in response.

I think it's simply inhumane to put the thousands of family members and friends of those who died in this tragedy through the stress caused by the protracted uncertainty as to who did what, and why, in the cockpit. And my view is that the scope for ongoing speculation does no favours for the interests of pilots or aviation safety.

The cockpit recorder almost certainly enables the investigators to distinguish between the voices recorded and identify which of those voices belongs to the PIC and which to the FO. And, based on my reading of previous posts, the cockpit recorder may have even picked up the 'clicks' of the fuel control switches. And the investigators almost certainly know which of the PIC and FO transmitted the MAYDAY. That all resolves to a small number of likely scenarios, which scenarios have been described (repeatedly) in this thread, all of which should already have been formulated by the investigators.

For the life of me, I cannot see the point of the investigators not coming out and saying: "At this point, we are confident of at least these facts: ... Unfortunately, it follows that we are confident that either the PIC or FO switched off both fuel control switches seconds after take off. That all leads us to be confident that one of X combinations of actions occurred in the cockpit, but we have yet to have any confidence as to what motivated any one or more of those actions: ..."

Look at how many NTSB update briefings occurred in the wake of the mid-air collision involving the CRJ and Blackhawk at DCA. The ATC recording is publicly available. What damage was done, to whom, by those update briefings or the publication of the ATC recording?

The ultimate assessment of the contents of the preliminary report is some time off in the future (contents, here meaning what is included and what is not). That being said, the comparison to the several briefings by NTSB in the wake of the 29 January 2025 midair collision at DCA is less valid than might at first seem to be the case.

First, the DCA collision occurred against the backdrop of significant weaknesses in the United States ATC system. The accident itself may have involved acts or omissions by the Army helicopter pilot or pilots, so there is that similarity in a general sense. But although a non-aviator, I did understand the many statements on the threads and in the general media about the difficulty of "visual separation" at night, particularly in the D.C. area and in the approach corridors to DCA. This is quite unlike the surpirse and/or disbelief that an experienced airline aviator would move fuel control switches to cutout at or nearly at the time of rotation. So the nature of the acts or omissions in question is quite different.

Second, it obviously occurred at Washington, D.C.'s close-in airport, which has been such a focal point of Congressional "air commuters".

There also is a difference in the likely litigation courses the two accidents will follow. On the premise that the WSJ report aligns with what appears to be the consensus on this thread - namely that the PM moved the switches although no one now knows why - and then reasoning further from that premise, the litigation to be faced by Air India will be considerable. I do not know the Law of India whatsoever, but under the Montreal Convention system for liability determinations and damages, I think it is a very easy straightforward assessment to say that the airline is going to face intense litigation challenges. In that light, the families will have their day in court (I mean, even without knowing Law of India, I think that's safe to say). Going beyond what - if I am reading and understanding the posters with actual significant investigation experience correctly - is the formal or nominal charge of the AAIB in this matter is not required in order to help the families. (And how bad would it be for them if the AAIB had to retract or materially change some information released ahead of determinations with certainty?)

Not least, in the DCA accident the legal landscape is quite diffrerent. Without rehashing the (perhaps tedious) posts I put on the DCA thread, the scope of available legal relief is quite limited under applicable federal law (just for reference, the "discretionary function exception" to the allowance to sue federal entities will almost certainly limit the scope of recoveries available from the Army or FAA/Dept of Transportation; the airline can be sued but it will be, in my not-so-hmo, ridiculous and mercenary to do so, as the CRJ and its tragically ill-fated crew had done nothing wrong).

Somewhat relatedly, on the WSJ article, while its sources are unnamed, I'm trying to recall a single article published in that newspaper (including online) about a major aviation incident which later was shown to have been inaccurate. Maybe there are one or more examples. Generally The Air Current's publisher got a very good start.

I have not posted on here in many years, but I feel compelled to do so now. I am a current 787 pilot and I have previously flown most Boeing types and an Airbus too. I also have an extensive background and qualifications in human factors, training and assessment. Before anybody reads any further, perhaps acquaint yourself with the notion of Occam's razor. That is, the simplest explanation is the most likely explanation. I was certain that after the preliminary report was released the preposterous conspiracy theories would finally cease, but no! It's 2025 and humans can no longer help themselves. In my opinion the captain committed suicide here. Simple.

To those suggesting an electrical phantom turned the fuel control switches off without them moving: no. Ask yourselves this: what made one pilot (PF and F/O in my opinion) ask the other "why did you cut off?" Firstly, some context. The 787 fuel control switches make a VERY distinct metallic *CLICK* sound as they are operated. EVERY 787 pilot knows it and won't forget it. It is audible even at high thrust settings owing to the 787's exceptionally quiet engines and cockpit. After rotation the pilot flying is fixated on the HUD; rotating towards the TOGA reference line (~12 degrees pitch attitude) and putting the flight path vector over the flight guidance cue. One hand would be on the control column and the other on the thrust levers. Alternatively he could have had both hands on the control column. In either scenario, the pilot flying's (again, my opinion the F/O's) inboard arm would block his peripheral view (he's focused on the HUD, remember) of the center pedestal and the fuel control switches. HE WOULD NOT SEE THE PM TURN THE FUEL CONTROL SWITCHES OFF. Ipso facto. We know the F/O was PF from the report. If the F/O stopped flying the aircraft and reached down to move the FCS from cutoff to run the captain would've plainly seen the whole thing. I can't imagine "why did you cutoff?" would be his words of choice! More like "WTF ARE YOU DOING?!?" More to the point, if the PF (F/O) did stop flying and reach down to cut one engine off, the captain would have had time to either stop him flicking the second FCS off or at least quickly flick them both back to run and potentially save the day. This plainly did not happen. So it was almost certainly the PM (Capt) that moved the fuel control switches.

So what would make the PF ask the PM "why did you cut off?" if he couldn't see it happen? You would never assume with a loss of thrust that the switches had been turned off. Never. It's not a procedure. It's not a thing. Bird strike? Sure. Fuel Contam? Maybe. But the point is, in the heat of battle at 150 odd feet, you'd never jump to the conclusion that the fuel control switches were off. Never. So what triggered the PF asking the PM why he cutoff? Because he HEARD the fuel control switches move from run to cutoff, that is why. He heard those distinctive *CLICK* sounds (and yes, you can easily flick them both in less than a second FWIW) followed by the engines immediately rolling back. He would then have looked down at the switches and noticed they were in cutoff. The point to be made here is that the switches were moved by the captain. They made their distinct sound. There were no phantoms. They cannot move on their own. They didn't simultaneously fail. This drew the PF's attention away from flying and triggered the question "why did you cutoff"?

Inadvertent selection of the wrong switches? No. The PM was a training captain with thousands of hours experience on the jet. I asked one of our most experienced examiners how many times he'd seen that done. The answer was "zero". Even the stab switches next to them. They're red, guarded and are of a completely different shape and operation. Gear or flap? Come on. I think we're starting to stretch things a bit now. EVEN IF it was inadvertent switching. The INSTANT you'd made that error, you'd go "oh whoops", and flick them back to run. I know startle... I teach it. This is different. You don't flick the fuel control switches off, hear the engines roll back and sit there wondering what happened for 10 seconds AFTER THE F/O JUST ASKED YOU IF YOU CUTOFF! You did something that had an instant effect on the flight. The report indicates that "why did you cutoff" was asked just after both engines rolled back. But it took another 10 seconds to flick the FCS' back to run. If it was inadvertent, the instant the other pilot called out your error you'd correct it. The report makes it clear that there was 10 seconds between that happening. 10 seconds is a LIFETIME in that situation. The training captain knew what he was doing. He only switched the FCS' back to run once he knew it was moot.

So, why did he respond that he didn't move the switches? As per other input from people on here, when people are suicidal they often want to throw authorities off their trail. Or maybe he wanted to confuse the F/O so he didn't flick them back to run himself, or to just buy himself more time while the F/O tried to wrap his head around things? Maybe he didn't want the F/O to die knowing it was a suicide mission. Maybe we'll find out more in the final report or police investigation if things proceed that way. Maybe we'll never know.

I acknowledge that this is my opinion and of course there could be things we don't yet know about, but I must say I'm surprised that some of the theories on this professional pilot forum are no more coherent or logical than those being sprouted on social media.

I'm sensing that the Journal, while not immune whatsoever to commercial pressures, is well-sourced.

From the article: "The preliminary details have fueled the belief among some U.S. officials that criminal authorities should review the matter, as would likely be the case if the crash had occurred on American soil, people familiar with the matter said." This assertion, stated without attribution, is fairly viewed as having unknown credibility.

But it also might be understood differently when read in a context of the entire reporting which includes these two quite specifically attributed statements:
From the article: "An NTSB spokesman said that [NTSB Chair Jennifer] Homendy has been fully briefed on all aspects of the Air India investigation, including the cockpit voice recording and details from the flight data recorder. Homendy said her goal in working with Indian authorities was 'to quickly determine whether the crash presented any immediate safety concerns to the traveling public.'\x94 (internal quotation as in article)
........
From the article: "The Indian authorities\x92 preliminary report finding that the fuel control switches were flipped in succession, one second apart, suggested a deliberate act, according to Ben Berman, a former senior NTSB official who helped oversee the U.S.-led investigation into the crash of EgyptAir Flight 990 in 1999.

Berman said that, prior to the engines\x92 fuel being cut, the report didn\x92t suggest anything out of the ordinary for what should have been a routine takeoff and climb-out. 'There was nothing to prompt the crew to perform emergency procedures, become stressed, or do anything except rotate the nose up and retract the landing gear, like they had done so many times before,' Berman said." (internal quotation as in article)

The Air Current's reporting just prior to release of the preliminary report - based on unnamed sources possibly with close access to the AAIB - turned out to have been correct. Would NTSB have offered the comments it did, if it believed the Journal was about to publish stuff it was just making up?

Edit: the WSJ also, on Wednesday, published a column by one of its regular staff columnists who thinks pilotless airliners are inevitable and would be a much better system architecture. Perhaps in publishing this reporting about the Air India accident the Journal is hoping to preserve credibility among the industry and regulators, despite the nonsense (imho) of that part of the column (most of it concerns the apparent cause of the accident, which - as some post many many pages ago predicted would occur - becomes supposed justification for Captain HAL).

That is a compelling observation that is hard to avoid the uncomfortable facts. The audio tape for the couple of seconds after takeoff will be getting a close scrutiny.

The answer is slightly complicated. The FADEC has the authority to move the fuel metering valve to the 'full closed' position - which also causes the High Pressure SOV to then close. However this is normally only used during engine starting, and that part of the logic is disabled once the engine is running. However, there is the overspeed protection circuit which can also close the HPSOV. TCMA uses the overspeed protection system to shutdown the engine.

The HPSOV is driven by the aircraft using 28 Vdc power from the battery bus. The FADEC isn't involved - although it does get an indication of the fuel condition switch position, but that's not used except during starting. A 'false' fuel condition switch input of Cutoff will not cause the FADEC to do anything once the engine is running.