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| MikeSnow
July 15, 2025, 20:33:00 GMT permalink Post: 11923203 |
Do the STAB cutout switches and Fuel cutoff switches share any connectors that could have been inadvertantly cross-connected? Etc. It would not be the first time that an engineer had innocently done something that later caused an accident. And I haven't read anything about possible nefarious action by a (disgruntled?) engineer - but I've seen lots of accusations directed at the pilot(s)...
But, even if this were possible, there are problems with this hypothesis too. The problem would most likely be discovered during engine startup, if the engines are started one by one, not at the same time, as they probably wouldn't start unless both switches are set to RUN. And not sure how this would fit the various delays recorded on the FDR. And you still need something/somebody to move at least one of the switches after rotation to trigger the issue. Both switches being moved by the pilots still seems much more likely to me than some technical issue.
A \x93status\x94 message is the lowest urgency message the crew can get on a Boeing aircraft.
Its a notification at best, requires no checklist. Maintenance will do a system check in the Maintenance Computer terminal also known as a BITE test. Clear the status message and that\x92s it. They are certainly not taking tools to take the throttle quadrant apart in search of a software fault. The status message has nothing to do whatsoever with the Fuel Cutoff Switches. Subjects
FDR
Fuel (All)
Fuel Cutoff
Fuel Cutoff Switches
RUN/CUTOFF
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| TURIN
July 15, 2025, 20:54:00 GMT permalink Post: 11923218 |
SLF here, but I did read all 3 threads. To me, this doesn't seem likely. But it got me thinking, what about the fuel switches being partially cross-connected left to right and right to left? If each of the 8 channels (4 for each switch) has its own connector, it could be possible. From what I understood from earlier posts, from the 4 channels of each switch, there are 2 can shut down an engine. If that's the case, assuming some cross-connection, a single switch movement might be able to affect both engines.
But, even if this were possible, there are problems with this hypothesis too. The problem would most likely be discovered during engine startup, if the engines are started one by one, not at the same time, as they probably wouldn't start unless both switches are set to RUN. And not sure how this would fit the various delays recorded on the FDR. And you still need something/somebody to move at least one of the switches after rotation to trigger the issue. Both switches being moved by the pilots still seems much more likely to me than some technical issue. "Software faults" do not usually come out of the blue, for no particular reason. Just because it's recorded by software it doesn't mean that it's not something hardware related that triggers it. In a previous reply, not sure if in this thread, it was mentioned that the message meant that there was implausible data coming from those STAB cutoff switches, if I remember correctly. Something like a channel showing both on and off at the same time, or the other way around, or some other inconsistency. That could have been an intermittent issue, that might indeed not be reproducible with a BITE test, and just be cleared. But if the STAB cutoff switches did indeed have a problem, or one was suspected due to recurring reports, is it really so unlikely that they might try to look for some hardware issues, such as a loose connector? For the Lion Air accident involving MCAS, after repeated issues during previous flights, they did exactly that: disconnected and reconnected some connectors to check for issues, among other things. EG. GPS faults are common among aircraft that fly around Turkey and other troublesome areas of the world due to GPS 'spoofing' or jamming. The problem is known and a procedure to reset the fault and verify that there is no 'hard' fault hidden in the hardware is used every day. As I posted earlier in this thread, the Stab Trim (Posn) XDCR status message can be deferred under the MEL with a maintenance procedure that does not involve touching those switches. Last edited by TURIN; 17th July 2025 at 12:59 . Subjects
FDR
Fuel (All)
Fuel Cutoff Switches
MEL
RUN/CUTOFF
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| galaxy flyer
July 15, 2025, 23:58:00 GMT permalink Post: 11923333 |
Likely because the FDR readout showed the engines at the appropriate takeoff thrust, then the switches move, takeoff thrust goes away. Switches move back to RUN and the quick restart begins.
Subjects
FDR
Memory Items
Preliminary Report
RUN/CUTOFF
Relight
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| Triskelle
July 16, 2025, 19:21:00 GMT permalink Post: 11923904 |
From the discussion about the switches it would seem impossible to me that someone sitting in either the pilot or co-pilot seats could
almost simultaneously
unlatch and move both switches - although it could be done by someone else in the cockpit using two hands? I can believe that both switches could be reset within a few seconds with one hand though. Would a brief electrical fault (at rotation) show on the FDR as equivalent to a switch to 'off' (closing the fuel valve and deploying the RAT)? Apparently the switches were found to be in the 'on' position.
Subjects
Electrical Failure
FDR
RAT (All)
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| LiveSpark
July 16, 2025, 22:26:00 GMT permalink Post: 11924011 |
787 has RDC's - Remote Data Concentrators. Doing the same function. Two of the switch pole-sets go each to one of 2 different RDC's, that feed the EAFR's / QAR, and the common core network so that any system that wants to know, can. The wiring is positive voltage from the RDC's to the switch and to GND through the common pin. So the RDC's would be able to detect anomalies such as both contacts open, or both contacts closed. The EAFR will see two independent channels per switch.
The other 2 contact sets feed latching relays (again driven each coil independently by dropping to GND at the switch) that then drive spar valves and reset signals to the FADEC Channels. (and more). So - for the benefit of those that hang on to the 'possibility' of electrical gremlins and 'ghost' switch signals. Each switch has 4 mechanically separated 'channels' - 2 of which do electromechanical things to the engines through separate paths, the other 2 feed through independent paths the FDR and the rest of the computer systems. The results of the electromechanical actions also feed back to the FDR. Thus the readout from the EAFR will PROVE that the switches MUST have been PHYSICALLY MOVED. Subjects
EAFR
FADEC
FDR
Fuel (All)
Fuel Cutoff
Fuel Cutoff Switches
Spar Valves
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| BrogulT
July 16, 2025, 23:20:00 GMT permalink Post: 11924037 |
Subjects
FDR
Fuel (All)
Fuel Cutoff Switches
Honeywell
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| AirScotia
July 17, 2025, 14:46:00 GMT permalink Post: 11924417 |
If it was a suicide attempt, wouldn't the pilot responsible wait until the aircraft had got a bit higher before operating the fuel switches and follow it up with full forward stick ? At low level the outcome wouldn't have been in any doubt. Nose down would be instinctive to someone who wanted to crash and with the arms locked in the extended position it would be very difficult for the other pilot to override him.
I agree that it may have been a physical health issue causing momentary confusion. Or it may be related to medication. But I think it's hard to dispute that human fingers moved the switches. Subjects
FDR
Fuel (All)
Fuel Cutoff Switches
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| za9ra22
July 17, 2025, 14:59:00 GMT permalink Post: 11924424 |
And in fact, I would be shocked if the pilot responsible didn't expect that his identity would be knowable in due course in any event - just as many here have supposed. Certainly, no life insurance policy would pay out on a claim until this was settled to the insurance company's satisfaction. To add: This is pertinent because it really does show that if this were a suicide by pilot, the pilot either knew he would be identified and named, or didn't care. Subjects
FDR
Wall Street Journal
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| Icarus2001
July 17, 2025, 16:07:00 GMT permalink Post: 11924452 |
If suicide, this is the only part of flight where the FDR will not identify which pilot is responsible.
Subjects
FDR
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| za9ra22
July 17, 2025, 16:23:00 GMT permalink Post: 11924460 |
Why would AAIB include that red herring in the prelim when they had the switches in their possession and included pics of them in the report? I have to admit that I took a bite of that herring and still have a nagging issue with myself not being able to see a dog on the lower part of the left switch. But I'm more inclined to think badly of the AAIB for including the herring.
To not detail the background would have been to omit a clearly pertinent fact which would have left others questioning the authority of the report for not covering it. The report itself then clearly states: "At this stage of investigation, there are no recommended actions to B787-8 and/or GE GEnx-1B engine operators and manufacturers." to ensure it is known that no defects were found at the time of the report being issued. I suspect it is written as it is because at this point, there is no evidence the investigation can provide as to how the switches 'transitioned', let alone why. Subjects
AAIB (All)
FDR
Fuel (All)
Fuel Cutoff Switches
Preliminary Report
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| jimtx
July 17, 2025, 18:06:00 GMT permalink Post: 11924525 |
Not sure why you would think the paragraph in the preliminary report was a red herring - it's a statement of historical context directly relating to the fuel control switches which the investigation had found in the FDR record as having 'transitioned' to OFF before 'transitioning' ack to ON.
To not detail the background would have been to omit a clearly pertinent fact which would have left others questioning the authority of the report for not covering it. The report itself then clearly states: "At this stage of investigation, there are no recommended actions to B787-8 and/or GE GEnx-1B engine operators and manufacturers." to ensure it is known that no defects were found at the time of the report being issued. I suspect it is written as it is because at this point, there is no evidence the investigation can provide as to how the switches 'transitioned', let alone why. They have the switches. Subjects
FDR
Fuel (All)
Fuel Cutoff Switches
Preliminary Report
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| Chernobyl
July 17, 2025, 18:27:00 GMT permalink Post: 11924531 |
I'm genuinely puzzled about the statements above (and many more similar examples in previous posts too numerous to count). I checked the language in my own policy (a common term life insurance policy in Canada) and it explicitly states under exclusions: "Suicide within 2 years of the effective date of coverage or reinstatement, or the date of any increase in coverage, is not covered." [again, emphasis mine] Beyond the 2 year exclusion period, suicide is considered an insured risk. So, is everyone just presuming that insurance policies don't/won't pay out in the event of suicide? If so, I have at least one example that counters that common knowledge. Perhaps this is an exclusion in flight crew life insurance -- I don't rightly know (as simple SLF I'm not aware of those Ts & Cs). Can anyone point to an authoritative source (as opposed to just surmised knowledge) which states that a life insurance policy will not pay out in the event of suicide (past any exclusion period) and hence could be motivating factor in the decision-making of this incident? Further, it should be from an Indian life insurance company that would typically cover pilots (as this is the relevant scenario). For further clarity: I take no position on whether this incident was triggered by intent or not. I just want to better understand whether this particular aspect may or may not have been a contributing factor. Subjects
FDR
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| tdracer
November 28, 2025, 19:32:00 GMT permalink Post: 11997347 |
There are no known ways that a 'core' system fault could shutdown the engines. I do wonder about the stab system faults - although apparently corrected, a good pilot would have reviewed the log and known there had been issues. It might have left him 'pre-loaded' to take action for a stab system problem - which turned into an 'action slip' of moving the fuel levers. Subjects
Action slip
FDR
Fuel (All)
Fuel Cutoff Switches
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| Musician
December 24, 2025, 08:41:00 GMT permalink Post: 12010285 |
For the FDR to record the switch moving, while the engine responds to the switch moving, requires two different circuits on different poles of the switch to change state at the same time. This could only be achieved by flipping the switch. I have also never heard of a solenoid (such as driving the fuel valve) to be actuated by solar radiation. I understand that the fuel cut-off part of the circuitry is entirely analog (happy to be corrected if not). Subjects
FDR
Fuel (All)
Fuel Cutoff
Fuel Cutoff Switches
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| Musician
January 23, 2026, 02:00:00 GMT permalink Post: 12025513 |
I thought we were discussing the Air India crash - not something that happened 15 years earlier during flight testing.
There is a reason they flight test new aircraft - to find problems like that. Anyway, what's the relevance to Air India? It didn't lose power until the engines were shutdown... The problem is that that's not where the known evidence leads (as we know), and that "whistleblower" doesn't change that. They're trying to portray the 787 as a fault-ridden aircraft that ought to not be allowed to fly, in spite of its long track record of flying safely (once the battery issues were solved). It's kind of like the people shouting "the vaccine is going to kill us all", despite a marked absence of dead bodies at scale 4 years later. For that end, they're avoiding putting their facts in any kind of context, and instead peddle big numbers, "secrets", and an implied coverup, but there's no hard evidence for any of it (I don't think we get to see these 2000+ reports?). So the evidence of the FDR must be wrong—otherwise their narrative doesn't work. Why is it wrong? "Electrical problems", meaning "magic". If you believe in magic, where a fault ex machina just so happens to achieve what you need it to achieve, as if reality was a cheesy Hollywood production, then the AI171 crashed all by itself. Those of us who don't believe in electrical magic follow the evidence instead. Subjects
AI171
Electrical Failure
FDR
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| Musician
January 24, 2026, 09:01:00 GMT permalink Post: 12026247 |
Very interesting article in the Daily Telegraph.
The over riding impression I get is one of vested interests protecting their own position rather than following the evidence. https://apple.news/AHSrBmul0Tv-yToeImigXTA There's the old "the RAT deployed early" (assuming it always takes a full 6 seconds to spool up), the water leak, the "can't move both switches in a second", and new "the aft FDR looks like it burned before the crash". And this, which is as yet unsubstantiated, and is likely not relevant at all:
Just 15 minutes before take-off, the aircraft\x92s bus power control units (BPCUs), which manage the electrical systems, sent real-time signals to Boeing and Air India indicating malfunctions with both BPCUs.
In isolation, none of these problems is classed as major issues, but taken together, according to some experts they show a pattern of electrical problems that point to issues with the core network.
According to reports in India, in the minute before the aircraft took off, and almost certainly as it was heading down the runway, the 787\x92s aircraft communications addressing and reporting system sent a fault code to Boeing and Air India which indicated that the Fadec was receiving corrupted data from an engine monitoring probe.
Pierson says: \x93That aircraft was sending out fault messages before it took off. That is a big red flag. The aircraft health management system was also sending real-time data to Air India and Boeing so they had that information before the fires were even put out. None of that information was included in the preliminary report.
Last edited by Musician; 24th January 2026 at 11:14 . Subjects
FDR
Preliminary Report
RAT (All)
RAT (Deployment)
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| Ver5pen
January 24, 2026, 18:30:00 GMT permalink Post: 12026533 |
Non-paywalled version:
https://www.aol.com/articles/sabotag...060100148.html
There's the old "the RAT deployed early" (assuming it always takes a full 6 seconds to spool up), the water leak, the "can't move both switches in a second", and new "the aft FDR looks like it burned before the crash". And this, which is as yet unsubstantiated, and is likely not relevant at all:
Just 15 minutes before take-off, the aircraft\x92s bus power control units (BPCUs), which manage the electrical systems, sent real-time signals to Boeing and Air India indicating malfunctions with both BPCUs.
In isolation, none of these problems is classed as major issues, but taken together, according to some experts they show a pattern of electrical problems that point to issues with the core network.
According to reports in India, in the minute before the aircraft took off, and almost certainly as it was heading down the runway, the 787\x92s aircraft communications addressing and reporting system sent a fault code to Boeing and Air India which indicated that the Fadec was receiving corrupted data from an engine monitoring probe.
Pierson says: \x93That aircraft was sending out fault messages before it took off. That is a big red flag. The aircraft health management system was also sending real-time data to Air India and Boeing so they had that information before the fires were even put out. None of that information was included in the preliminary report.
I still don\x92t believe we have got a clear answer on the recording interval of the engine cutoff switch channel, if it\x92s 1s then the \x91debunking\x92 by saying it can be done very quickly is moot as (near) instant would record as 1s I believe and the RAT element is obviously very relevant, if RAT deployment is not recorded then one has to infer when it deployed based on when it delivered hydraulic/electric capability. And this will come down to counting seconds, any indication that the RAT may have deployed before the fuel cutoffs were recorded as moved is obviously hugely consequential it\x92s easy to dismiss these narratives as vested interests but let\x92s be honest everyone has a vested interest here and blaming the pilots has been the go to when in doubt for a very very long time- probably as long as aviation has existed in the absence of explicit evidence (does the CVR have more to tell?) of deliberate action or pre-planning this is a horrifically complicated investigation as there will always be plausible deniability on all sides and different courts/judges will rule on it very differently based on their own biases and views Subjects
CVR
FDR
Fuel (All)
Fuel Cutoff Switches
Preliminary Report
RAT (All)
RAT (Deployment)
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| Someone Somewhere
January 24, 2026, 20:21:00 GMT permalink Post: 12026564 |
Non-paywalled version:
https://www.aol.com/articles/sabotag...060100148.html
There's the old "the RAT deployed early" (assuming it always takes a full 6 seconds to spool up), the water leak, the "can't move both switches in a second", and new "the aft FDR looks like it burned before the crash". And this, which is as yet unsubstantiated, and is likely not relevant at all:
whilst intentional action is the most obvious explanation one can’t ignore data and technical grounds if one is also going to dismiss counter theories on technical grounds
I still don’t believe we have got a clear answer on the recording interval of the engine cutoff switch channel, if it’s 1s then the ‘debunking’ by saying it can be done very quickly is moot as (near) instant would record as 1s I believe
and the RAT element is obviously very relevant, if RAT deployment is not recorded then one has to infer when it deployed based on when it delivered hydraulic/electric capability. And this will come down to counting seconds, any indication that the RAT may have deployed before the fuel cutoffs were recorded as moved is obviously hugely consequential
The engines ran down after the switches were recorded moving. Even if the RAT deployed, that does not suggest that the crew switched the engines off because of an engine failure. No crew is going to shut down the engines down simply because a RAT deploys unexpectedly.
it’s easy to dismiss these narratives as vested interests but let’s be honest everyone has a vested interest here and blaming the pilots has been the go to when in doubt for a very very long time- probably as long as aviation has existed
in the absence of explicit evidence (does the CVR have more to tell?) of deliberate action or pre-planning this is a horrifically complicated investigation as there will always be plausible deniability on all sides and different courts/judges will rule on it very differently based on their own biases and views I don't think you can or will effectively prove whether it was intentional or some kind of an action slip, and by which pilot. I think the accident report will be able to very clearly and with no reasonable doubt show that the switches were physically moved. From the article:
The alternative is
too awful for them to contemplate
: that one of the pilots murdered hundreds of people as collateral damage in a suicide.
Because the aft flight recorder was destroyed, investigators cannot retrieve the one piece of information that it alone contained – the moment it stopped working, which might have provided a vital clue about a fire or electrical failure in the moments before the crash.
The aft EAFR was substantially damaged and could not be downloaded
through conventional means.
The CPM was opened to inspect the memory card. The damage was extensive.
Last edited by Someone Somewhere; 24th January 2026 at 20:32 . Subjects
APU
Action slip
CVR
DFDR
EAFR
Electrical Failure
Engine Failure (All)
FDR
Fuel (All)
Fuel Cutoff Switches
NTSB
Preliminary Report
RAT (All)
RAT (Deployment)
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| Someone Somewhere
January 25, 2026, 09:43:00 GMT permalink Post: 12026797 |
The responses to the article are very interesting. And pretty much go to reaffirming my point about vested interests.
it was the same with the MH370 accident. If you’re American or worked/flew Boeing aircraft you’re more likely to blame the pilots. If you’re Indian or Asian you’re more likely to blame the aircraft. Unless someone produces a smoking gun, which is very unlikely, then the causes will always be up for debate. Here in the U.K. we had the Chinook crash, where the pilots were instantly blamed. It makes me very uncomfortable to blame one individual for mass murder without a smoking gun as such. We had some discussions over in 787 GEnx loss of aircraft data will result in engine shutdown which I won't repeat in full, but there doesn't seem to be any credible way to get that result from a system failure without dealing in one-in-a-quadrillion events. The monitoring channel going to the RDCs and EAFRs is independent from the relay logic that closes the fuel valves. Most of the "we'll never know" accidents don't have full FDR and CVR data. This one does. I'm usually not on Boeing's side but the evidence is pretty overwhelming here. Subjects
CVR
EAFR
Engine Failure (All)
Engine Shutdown
FDR
Fuel (All)
Fuel Cutoff Switches
GEnx (ALL)
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| Musician
January 25, 2026, 09:58:00 GMT permalink Post: 12026812 |
The responses to the article are very interesting. And pretty much go to reaffirming my point about vested interests.
it was the same with the MH370 accident. If you’re American or worked/flew Boeing aircraft you’re more likely to blame the pilots. If you’re Indian or Asian you’re more likely to blame the aircraft. Unless someone produces a smoking gun, which is very unlikely, then the causes will always be up for debate. Here in the U.K. we had the Chinook crash, where the pilots were instantly blamed. It makes me very uncomfortable to blame one individual for mass murder without a smoking gun as such. It's incorrect to say we're blaming the pilots; the prevailing opinion seems to be that ONE pilot (but we don't know who) inadvertantly flipped the switches in lieu of another task ("action slip"). It's incorrect to call this "mass murder", and I don't think anyone did (and stayed unmoderated). It's also incorrect to say there's no smoking gun: the preliminary report is very clear that the fuel cutoff switches transitioned, i.e. somebody moved them such that one set of contacts was registered by the electronics and the FDR, and another set of contacts operated the fuel valve. The whole accident sequence follows from this logically and without contradictions. It is clear that MH370 deviated off course intentionally, but we cannot say if a pilot planned this, or if the aircraft was hijacked. It is false to say that the pilots were blamed "instantly" for the 1994 Chinook crash; the RAF board of inquiry did not do that. That ruling was overturned at first, but two subsequent inquiries re-overturned that, so that the pilots stand exonorated today. Please do review the facts. Subjects
Action slip
FDR
Fuel (All)
Fuel Cutoff
Fuel Cutoff Switches
Preliminary Report
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