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

You are absolutely correct insofar that is the most likely explanation, but see answer above. While I have found, as I suspect most, the deliberation angle most likely, since day one, it isn\x92t really fit for discussion, so the other, admittedly slightly more unlikely avenues are more appropriate and more interesting imho.



But you also underestimate my history with spilling coffee on large amounts of switches, but while tangentially relevant, that is for another thread in another forum.o-)

Intermittent faults with spillage and switches fixed by cycling/fiddling is a thing, and it is not contrary to the facts from the report. It is possible. It is also, admittedly not the most likely.

Exactly, the report said transitioned, not moved. The report just says the recording shows change of status, it does not imply deliberate action to change it.

Timeline of known events with source attribution from the preliminary report:

08:07:33 ATC: Takeoff clearance
08:07:37 A-SMGCS: Aircraft starts rolling
08:08:33 EAFR: V1 153kts
08:08:35 EAFR: Vr 155kts
08:08:39 EAFR: Gnd-Air mode transition
08:08:42 EAFR: Max IAS 180kts, Eng 1/2 Cutoff switches activate within 1 second of each other
08:08:42 CVR: "Why did you cut off", "I did not" (exact time not specified)
08:08:42 A-SMGCS: RAT deployed (exact time not specified)
08:08:47 EAFR: Both engine N2 below min idle. RAT hyd pwr commences
08:08:52 EAFR: Eng 1 cutoff to RUN
08:08:54 EAFR: APU inlet door opens (auto start logic)
08:08:56 EAFR: Eng 2 cutoff to RUN
08:09:05 ATC: Mayday call
08:09:11 EAFR recording stops

Fuel cutoff switches operated within 1 second of each other suggests to me that the locking mechanism wasn't working as per (SAIB) No. NM-18-33. Any loose item could have accidentally (or not) operated the switches (including hands).

Can someone with the engineering knowledge build a timeline/timeframe for fuel cutoff switch RUN to CUTOFF -> fuel stops -> engine flameout -> N2 drops to ? -> VFSGs quit -> RAT deployment starts -> RAT full power -> APU deployment start?
Does the RAT really start providing power in 4 seconds from the E2 fuel cutoff switch RUN -> CUTOFF?


Timeline from AAIB and the public CCTV video:

08:08:33 v1 153 kts
.
08:08:35 vr 155 kts
.
.
.
08:08:39 Liftoff, A/G Air Mode, rotation at 00:18 in public CCTV video
.
.
08:08:42 E1 Fuel Cutoff Switch RUN -> CUTOFF, 180 kts
08:08:43 E2 Fuel Cutoff Switch RUN -> CUTOFF
.............? N1 N2 begin to decrease
.............? "Why did you cutoff", "I didn't"
.............? Airport CCTV shows RAT
.............? N2 < idle speed
08:08:47 RAT hydraulic power
.
08:08:49 Public CCTV video: visible loss of thrust, Alt < 200ft using wingspan
.
.
08:08:52 E1 Fuel Cutoff Switch CUTOFF -> RUN, CCTV video: visible descent
.
08:08:54 APU inlet door begins opening
.
08:08:56 E2 Fuel Cutoff Switch CUTOFF -> RUN
08:09:05 MAYDAY
08:09:11 EAFR Recording stops
08:14:44 Crash Fire Tender leaves airport

Nothing in the report suggests that the engines began to run down before the fuel was selected to cutoff. The report states a sequence of events for power loss which begins with the switches being moved to cutoff. The maximum airspeed was immediately before the switches were moved, so there had not been a power rundown prior to that:

This is a preliminary report. It is quite detailed for a preliminary report.

Examining the before-takeoff checklists seems like it would be akin to examining the re-arrangement of the deckchairs before the titanic even hit the iceberg.

The engines were switched off. Unlike Embraer, B & A have no protections stopping you switching an engine off inadvertently. From everything in the report, everything operated exactly as designed. I am not certain of how long the relight window is without windmilling speed, but +- 10 seconds seems entirely reasonable.

The outstanding question that presumably requires much more in-depth investigation of the wreckage items and CVR audio is whether:

• the cutoff switches were operated deliberately (and by who)
• the cutoff switches were operated inadvertently (and by who)
• the cutoff switches were bumped (by what) and the guards failed or weren't installed
• some electrical failure perfectly mimicked both many-pole switches being operated, then being operated again (seems unlikely)

I haven\x92t seen this question asked and answered so apologies if I\x92ve missed it.

What observation(s) would or could have alerted either pilot to the fact that the fuel cutoff switches had been set to CUTOFF?

There is an EICAS message that comes up when an engine is shutdown (there is a small delay), which might prompt them to look at the switch - or just the sound the switch makes could prompt a quick glance down at the switch.

I don’t know if the FDR measures the switch position or the electrical signal. The latter is probably more likely, although there has been much discussion around potential scenarios involving accidental switch movement as well as possible causes of electrical glitches. Let’s assume that the switches were actually moved, and ignoring the “bad faith” scenario, we need a situation that encompasses the switches being moved to Cutoff by one pilot, this action being queried by the other pilot and denied by the pilot who moved the switches.

For consideration, here is a possible scenario that hasn’t been mentioned yet and encompasses the frailty of human performance. The report mentions that the flight crew on the immediately prior flight had written up a "STAB POS XDCR" status message, and that troubleshooting was carried out. I wonder if the scenario could be that the accident crew received a Stabiliser EICAS message on or around take-off and the Capt (who was PM) decided to action the first checklist item immediately from memory, by intending to move the Stab switches to Cutoff but moving the fuel switches instead. As in all modern Boeings, the Stabiliser Cutoff switches are immediately next to the Fuel Cutoff switches and operate in the same sense (i.e. down for Cutoff). They are guarded and never normally moved but, with an intent to move the stab switches, “muscle memory” (cerebellum activation if you prefer) may have taken the Captain’s hand to the Fuel switches, which are operated on every flight. The FO (who is PF) is manually flying at this stage sees and queries it. The Capt denies it, as he doesn’t realise what he has done (confirmation bias perhaps). After a few seconds, the terrible mistake is realised, and the fuel switches are moved back to run, but sadly too late and the Capt makes a Mayday call.

Perhaps a bit of a stretch but not as much of a stretch as many of the other scenarios in this thread. I think it is a real possibility. Sadly, the only other explanation that I can see is the deliberate “bad faith” scenario, which we would all hope is incorrect.

Fly Safe
PJ88

Not on the take-off roll. It was 3 seconds after liftoff.

This is pure speculation but I can envision the following sequence of events that would match the timeline and the little we know from the CVR and sequence of events.
- While PF is concentrated on flying the airplane, PNF moves the switches from RUN to CUTOFF in quick succession (for whatever reason).
- PF doesn't notice that the switches have been moved (again, he is concentrated on flying) but soon perceives the loss of thrust and sees a message on EICAS.
- PF looks down to check throttle position. It takes him a couple seconds to realize that the switches are in CUTOFF position.
- PF asks PNF (and his superior) "Why did you cut off the engines?" (or something similar). PNF anwers that he didn't (a lie, but we don't know if deliberate or just confusion / mental breakdown)
- PF realizes that PNF is in a wrong mental state, and attempts to restart the engines. It takes him a couple of seconds to move both switches because his other hand is on the yoke trying to stabilize the airplane.
- By then the airplane has lost too much energy for a successful recovery. One of the pilots calls MAYDAY because he knows that they are about to crash.
This sequence would match the timeline between the initial fuel cutoff, and when the switches were moved back to run position, and would actually indicate great presence of mind and quick decision from the PF.
Again, this is pure speculation but it would match well with the little information we have.

A plausible theory, however, if that were indeed the case wouldn't supporting FDR data be available/have been included in the initial report?

It\x92s fascinating to read all the what-ifs, some even more delusional then others.

• There are no cup holders close to the fuel cutoff switches
• We don\x92t hand each other tea at rotation.
• There is no g-force during rotation, we don\x92t jank the airplane of the ground. It\x92s a 3 second rotation to approximately 15 degrees.
• No worn switch would \x93fall over into cutoff\x94 when pitching up.
• The trim cutout switches are totally different design and are checked during the cockpit setup
• The PF places both hands on the yoke at V1 and looks outside and inside at the speed and attitude information throughout V1\x85Rotate\x85Positive rate\x85gear up.
• In the simulator, the instructor programs a V1 cut at their control station.
• The CA hands are on the thrust levers and guarding the yoke until the automated V1 call then the thrust levers hand gets pulled off to avoid the temptation of a reject above V1.
• Headsets are on separate channels on the cockpit voice recorder.
• The Indian authorities already know who said what and when.
• Cockpit cameras would have never prevented this, it would have only shown who pulled the switches.

I just looked at a picture of the 787 throttle area and I don't see how one would ever confuse the stabilizer cutout switches with the engine fuel cutoff switches. They are completely different in look and feel and operation.

Um, the flap and gear levers are a totally different design and they look, feel, operate differently. They are not even co-located, and occasionally people confuse them, withstanding decades of design efforts.
The fact that EICAS messages were recorded does not mean that they were provided in the preliminary report.

The notion is that around liftoff EICAS reported an error related to an error logged on the previous flight, that the PM felt it prudent to remedy the problem by cutting the stab cutoff switches, inadvertently cutting fuel. Action-slip, as mentioned countless times in these threads.

Sorry but the logic you are using is not considering "execution errors" which are not uncommon and, in aviation, can often have bad outcomes. They are, according to James Reason, "...errors which result from some failure in the execution and/or storage stage of an action sequence... \x94 Reason refers to these errors as failures in the modality of action control and, at this level, errors happen because a well - practised (but wrong) routine is activated. e.g. The Training Captain the the Nepal crash feathered the engine when he meant to select the flaps. This type of error is more likely when a person is stressed, fatigued or distracted.

A couple of thoughts

1. if I wanted to crash an ac I would physically fly it into the ground after t/o and NOT toggle a couple of fuel cutoff switches ?

2. these 2 vital fuel cutoff switches seem to be much too HANDILY positioned and easy to operate !

No experience of the 787 but lots on the 75/76.

The possibility of a perceived stab trim problem allied to an associated eicas message could have induced the PNF to go straight to the stab trim switches mindful of the problems associated with the 737 Max albeit a different type and a system not fitted in the 787 but an issue of which the Training Captain would have been well aware especially if he had been briefed on the stab messages from the previous sector. If, repeat if, he simply made the wrong selection and hit the fuel cut off switches then the holes have suddenly lined up. Unlikely, unfathomable perhaps but by no means impossible. Other than that....deliberate act ?

no experience of Boeing at all here but would a stab trim issue have been highlighted by EICAS that early? I assume Boeings have take off inhibit logic to hide certain less than emergency conditions until above ~1500AGL? Would a Stab issue have been serious enough to immediately pop up?

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?