Posts about: "Fuel Cutoff" [Posts: 302 Pages: 16]

Based on the news coming out of India, it appears that your suspicions regarding malicious intent may well be correct, but it is not the younger FO under suspicion as your post seems to suggest but the older more experienced captain. Other comments in this thread had already made me think that the younger pilot was the PF and that it was he who had challenged the PM because he would have been focused on flying the aircraft and would have had neither the time nor the inclination to adjust the critical fuel cut off switches which you yourself categorically claim would never be mistaken for other switches.

Long time lurker, first time poster here.

I cannot post links, but I came across a short video on Reddit (search for r/aviation and a post called "Fuel cut off switch". It shows someone operating the switches up and down, and the movement / considerable effort required to do so. The video is quite illustrative.

Hoping this contributes to the thread.

BF

Thank you for your kind reply. I confess to you that my post was not my best effort. I was in a deeply cynical mode when typing it.

I've reviewed the report a couple of more times since then, with some of the insights offered by PPRuNers to aid me. It had seemed to me, on first read, that they (whomever approved the final language of the report that we have all read) were hanging the FO out to dry...but...that may have been me reading too much between the lines . As others have noted, there's a lot not said.
Yes, that makes sense.

I've got some thoughts on compartmentalization still cooking in my head, to include "where was the captain's attention during take off, something he'd done hundreds of times?" I do not yet have those thoughts in coherent enough form to concisely present them to the very critical (as well it should be!) audience here.

The CRM piece has me grabbing at straws. I had mentioned in a previous post the bit about No Fast Hands and Confirmation of important switches/handles/levers before activating as general CRM principals, which it seems someone did not adhere to.

Nothing (yet) can tell me "what did the captain see with his eyes during the three seconds between leaving the ground and the switches being moved?"
I am not sure how much of the EICAS info ends up being recorded on the EAFR/FDR, or if there was a light that illuminated before the switches were moved, perhaps triggering a 'fast hands' moment / error...
Perhaps a subsequent report can shed some light on that.

And yes, it might have been an attempt at suicide for {X reasons} which are known only to someone who is now dead.

Unless I've missed it, za9ra22 has not been denying that a deliberate pilot action is not plausible. What za9ra22 and others \x97 I among them \x97 are arguing is that there is no credible evidence that either of the pilots deliberately moved the fuel control switches to CUTOFF intending to crash the airplane and kill all aboard . That is certainly one of the plausible possibilities, but only one of them. We don't know, cannot know, what actually happened, because we have available only fragments of evidence, fragments that don't come close to being sufficient to reach a conclusion. And accusing a pilot of deliberately killing hundreds of people, without conclusive evidence that he actually did so, is, IMHO, a grave injustice.

The prelim report very specifically states that the co-pilot ( the FO, younger pilot) was the PF.

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)

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.

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.

SLF here but an engineer who has spent most of his working life solving problems of one sort or another.
Would the FO, who is flying the aircraft (and presumably looking more or less straight ahead), notice out of the corner of his eye the Captain leaning over to move the fuel cut offs? Would that glimpse coincide with the loss of power? Is that when the comment "why did you do that" was made? Did he actually see the switches being turned off by the PIC or just assume that they had been, based on the aircraft performance loss?

I'm assuming that directly the engines lost power the FO would start looking for a cause. Where in the list of possible causes would the FCS be? Would he look down and see them in the "wrong" position fairly quickly (based on his "view" of the PIC leaning over) or would there be a more common reason for the loss which he would look at first?

He would have had to have had a reason to go straight to the FCS as the cause, surely? Further, what would be your reaction (as a pilot flying) to your colleague turning off the switches (again, not a remotely normal course of action). I think that mine would be something along the lines of "What the h*ll do you think that you're doing?" and maybe even reach down to turn them back on himself (which may indeed be what happened)
Sorry if this is badly worded, but I'm sure that you get my drift.

The preliminary report narrows things down a lot but not as much as it could have done. The report will have been approved by several people. What we see is their consensus. Why did they choose this version?

The report is written to point the finger directly at: (i) the fuel cutoff switches and (ii) either pilot error or pilot mal-intent using them. The report is not written to point the finger at an electrical or mechanical malfunction.

We have all role-played in our heads what would have been said in the cockpit in different scenarios. The investigating team already knows. They could have disclosed more of the cockpit conversation, which would be a lot of help to us PPRuNers, but didn't need to. They have let Boeing and the type off the hook and put the blame on the pilots. They have fulfilled the primary purpose of an investigation -- to find out what happened.

Interestingly, they did not disclose whether it was error and mal-intent. Perhaps that is because they couldn't answer the grisly question: which is least worst, from the point-of-view of the airline, the victims' families and future customers?

Two posters above have quoted AvHerald's report that "... India's media reports that the investigation is NOT focusing on a human action causing the fuel switches to appear in the CUTOFF position, but on a system failure." One interpretation of this is that the investigation knows all about the human action and that the system they refer to is the industry's approach to pilot mental heath and well-being.

YYZJim

In the middle of all hamster wheel posts, this one stands out. However, I do take issue only with the last point reported in this no longer reliable AvH website. Concerning the MN4 processor (Ive been looking into this one extensively prior to the preliminary report), according to the AD cited, MN4 board replacement on the GEnx1B was mandated within 12 years of production, engine that is, not A/C. According to the preliminary report AI171 engine 1 was produced 20 May 2012, engine 2 on 20 January 2013. This means that both AI171 engines were with replaced MN4 boards at the time of event, certainly taking into account that both engines have been mounted onto the aircraft in May and March 2025 respectively.

Sorry if my wording was not precise here - I meant the fuel cut off switches that more or less caused this accident.

It was stated earlier that 2 of the poles in the switch are wired to separate Remote Data Concentrators. The RDCs feed data into the Common Data Network (essentially an Ethernet LAN).

The EAFRs simply sniff the required data from the CDN, so there's no DFDAU as such.

For some parameters, including the fuel cutoff switches, the EAFRs also record a "Source Index." For the fuel cutoff switches, there are 4 sources numbered 1 through 4 as well as a valid/invalid flag. I don't know what the sources are, but perhaps they're the 2 RDCs plus the 2 channels of the EEC/FADEC. It appears that source 1 (the default) is not the EEC.

I'm still not clear on something, no surprise there.

If you are the PF and you are just after rotation, and for whatever reason, the fuel control switches transition to "CUTOFF", when and how do you notice this?
Presumably your hands are on the yoke and you are looking very intently out the windshield. So, to me it seems unlikely that you saw whatever happened to the switches, however they moved.

Do you get a warning indication that the switches have moved? If so, then that would be what I needed to know. You got a warning and therefore you looked right at the switches.

If not, do you just notice that you have lost power? If that is the case, where do you look first? I presume it would be at the engine info gauges/displays.

What I'm getting at is what priority is given to looking at the fuel cutoff switches in this situation?
How long until you look at those switches as the possible cause of the engine problems?

Well this is probably why it took 10 seconds, whole right side of the flight deck would be blacked out. My guess is that the EICAS messages that you see during sim engine fires/relights training helped. Don't have the post but it exists earlier upthread but there is an fuel cutoff EICAS message that happens when fuel switches move. Obviously can never count out a side vision of the PM, especially if its not a traditional movement in that stage of flight.

Not a B787 pilot but many hours on its wide body predecessors.

It is conceivable that you could notice hand movement around the throttle quadrant in your peripheral vision (noone's hands are on the thrust levers between V1 and shortly after takeoff), however even if you didn't, you'd immediately notice the loss of performance. The instinctive reaction is big loss of performance -> quick glance across at instruments -> why are they winding back? Also if the fuel control switches were moved to cutoff you'd suddenly get EICAS messages saying the engines were shutdown. So there are immediate clues and it's only a minor head movement to see where the fuel control switches are because they're right down there behind the thrust levers. Then the immediate action for a dual engine failure, which would by then likely be obvious with both sets of instruments showing everything winding back, is "fuel control switches cutoff, then run". There is no significant pause in that action because it's only to reset the electronic engine controls, so the 10 second gap between setting them back to "run" is not explained by the dual engine failure procedure but perhaps by a startle factor. One way or another, your eyes are going to end up checking where those switches are.