[mxplxxx (OP)]

The Indian Dreamliner crash is baffling. Two manually operated switches turned the fuel delivery system off. The pilots discovered the situation and turned the switches back on, but it was too late. Turns out the part involved had a hybrid mechanical/electrical operation. And it was not built to interface with the Dreamliner fly-by-wire system. It had to be specially wired in.  See https://copilot.microsoft.com/shares/KVdRj6hdhrkyZdtB7U9p7 or https://copilot.microsoft.com/shares/p1KW5R3ZirgV6gZT2CeQZ(for a full explanation)

[paul cotter]

As far as I know, which ain't a lot, those switches have a detent position which must be manually overridden to change state- they have to be either pulled up or pushed down before changing from on to off, or vice versa. It looks to me to be a case of suicide/mass murder.

[Bored chemist]

Re "Try C2B"
How about Colin2B?

AI Overview
"C2B" in a fitness context typically refers to chest-to-bar pull-ups, a variation of the pull-up where the chest, specifically the area below the collarbone,..."

How about Colin2B?

(1) why have you pretended I said something I did not say?
(2) What about Colin?

[mxplxxx (OP)]

As far as I know, which ain't a lot, those switches have a detent position which must be manually overridden to change state- they have to be either pulled up or pushed down before changing from on to off, or vice versa. It looks to me to be a case of suicide/mass murder.

Pilot - not likely.  It is an electro-mechanical part wedded to the fly-by-wire system, The electro part will likely do the actual shutting down. It has likely malfunctioned, and the pilots are notified via a screen at which point they redo the switch-on process.

[paul cotter]

I don't think so, they have to be armed by being pulled up before they can change state- then the electronics could have an input. Maybe our resident aviator, Alan, could enlighten us?

[mxplxxx (OP)]

I don't think so, they have to be armed by being pulled up before they can change state- then the electronics could have an input. Maybe our resident aviator, Alan, could enlighten us?

Chances they appeared to be on, but the electronics had turned them off due to a malfunction in the fly-by-wire interface. The pilots would have noticed they were off via a screen or just the fact that the engines has stopped firing.

[mxplxxx (OP)]

Actually, the most likely scenario is that the fuel was heated to the point where something like vapour lock occurred. The aircraft had arrived from New Delhi 2 hours before takeoff from the crash airport and stood in the sun for 2 hours on a hot summer's day and with half its fuel already present from the New Delhi trip, More details here: https://copilot.microsoft.com/shares/SbZfnQtYao7QMemSuckmm

[alancalverd]

What was the time sequence? In the case of engine failure on departure, you have one go at restarting (which may involve cycling the fuel pumps)  then cut the fuel supply to minimise fire on impact.

It would be surprising if the aircraft had not been refuelled at Ahmedabad - the journey to Gatwick is more than 50% of the max cruise range of a 787, so 75% fuel load might be a reasonable estimate. Planes spend all day, every day, out of doors in all weathers, without suffering fuel problems.

Vapor lock? Improbable IMHO. The engines are started on the terminal apron, run through pre-taxi checks, run at "idle plus" during taxi, then checked at full power before releasing the brakes for departure. I guess a minimum of 10 minutes from start to takeoff run, which should clear any bubbles from the fuel lines.

[paul cotter]

Vapour lock with jet A(kerosene)? Not likely, could happen with petrol(gasoline). The fact is the fuel cutoffs were manually operated, whether by design or error.

[mxplxxx (OP)]

What was the time sequence? In the case of engine failure on departure, you have one go at restarting (which may involve cycling the fuel pumps)  then cut the fuel supply to minimise fire on impact.

It would be surprising if the aircraft had not been refuelled at Ahmedabad - the journey to Gatwick is more than 50% of the max cruise range of a 787, so 75% fuel load might be a reasonable estimate. Planes spend all day, every day, out of doors in all weathers, without suffering fuel problems.

Vapor lock? Improbable IMHO. The engines are started on the terminal apron, run through pre-taxi checks, run at "idle plus" during taxi, then checked at full power before releasing the brakes for departure. I guess a minimum of 10 minutes from start to takeoff run, which should clear any bubbles from the fuel lines.

All is explained in the link. The aircraft had a 50% full tank after the trip from New Delhi. This fuel would have been quite warm from that trip and become much warmer after sitting for two hours on a hot unshaded tarmac at midday on a hot summer's day in the middle of summer. Adding the cool fuel from beneath the tarmac may have resulted in bubbles or other such effects that could have compromised the pumping of fuel to one or both engines. At which point the pilots may have decided to try restarting the engines.

[paul cotter]

If that was the case we would have aircraft falling from the sky on a regular basis. The preliminary report stated that there was no problem with the fuel other than activation of the cutoffs.

[alancalverd]

If there is no evidence of prior mental illness or serious religious fanaticism shared by both pilots, I'd also be inclined to dismiss "pilot suicide".

If you want to kill yourself in a plane crash, you can take a little one from your local aero club and prang it into the sea or a field with no hassle, formalities or opposition from a copilot or computer. Much quicker and more certain than putting on a uniform and spending hours on crew briefings, inspections and paperwork before you start up. And if you are suddenly seized with an urge to take 200 passengers with you, don't switch off the fuel and call Mayday, just point the plane at something solid and go in at full power - "the Lubitz method".

[mxplxxx (OP)]

If there is no evidence of prior mental illness or serious religious fanaticism shared by both pilots, I'd also be inclined to dismiss "pilot suicide".

If you want to kill yourself in a plane crash, you can take a little one from your local aero club and prang it into the sea or a field with no hassle, formalities or opposition from a copilot or computer. Much quicker and more certain than putting on a uniform and spending hours on crew briefings, inspections and paperwork before you start up. And if you are suddenly seized with an urge to take 200 passengers with you, don't switch off the fuel and call Mayday, just point the plane at something solid and go in at full power - "the Lubitz method".

I totally agree with you. Also, the fact that there were two of them mitigates against suicide.

The fact that the part involved was not a fly-by-wire part and was also electro-mechanical and contained lead. The lead may have softened in the heat leading to a malfunction of the electro part. A perfect storm of heat.

[paul cotter]

At that point in the climb a serious error like cutting off the fuel to both engines is almost certain to be unrecoverable. So suicide is quite possible, just like the Airbus into the alps atrocity. One person at the end of their tether may have just snapped and said f*#k it, I've had enough- no one knows what is going on inside another person's head. Without detailed info we are all just speculating but the fact that no aircraft were grounded or extra inspections required suggests to me that the investigators knew quickly that the aircraft itself was not to blame. Despite Boeing's well documented problems this particular aircraft has had a stellar reputation for over a decade with widespread use. 

[Bored chemist]

. The lead may have softened in the heat leading to a malfunction of the electro part.

If the cockpit is hot enough to melt lead, your pilot is dead, and even that isn't your biggest problem.

[mxplxxx (OP)]

At that point in the climb a serious error like cutting off the fuel to both engines is almost certain to be unrecoverable. So suicide is quite possible, just like the Airbus into the alps atrocity. One person at the end of their tether may have just snapped and said f*#k it, I've had enough- no one knows what is going on inside another person's head. Without detailed info we are all just speculating but the fact that no aircraft were grounded or extra inspections required suggests to me that the investigators knew quickly that the aircraft itself was not to blame. Despite Boeing's well documented problems this particular aircraft has had a stellar reputation for over a decade with widespread use. 

- The FAA issued an advisory in 2018 warning of potential thermal cycling damage to the microprocessor controlling these switches; but it wasn't mandatory, and Air India didn't perform the recommended inspections.

See more on this via the following Copilot link - near the end of the conversation.
https://copilot.microsoft.com/shares/tifJQgjwXJgRU4dsrPjkx

[mxplxxx (OP)]

. The lead may have softened in the heat leading to a malfunction of the electro part.
I would imagine the electro part interfaces with the fuel pumps via the fly-by-wire system. 

If the cockpit is hot enough to melt lead, your pilot is dead, and even that isn't your biggest problem.

Not melt. Soften. And it is unlikely the microprocessor is situated in the cockpit.

[Bored chemist]

Actually, the most likely scenario is that the fuel was heated to the point where something like vapour lock occurred. The aircraft had arrived from New Delhi 2 hours before takeoff from the crash airport and stood in the sun for 2 hours on a hot summer's day and with half its fuel already present from the New Delhi trip, More details here: https://copilot.microsoft.com/shares/SbZfnQtYao7QMemSuckmm

The boiling point of jet fuel is well above that of water. The whole fuel system is maintained at positive pressure,
There will have been no vapour locks.
Stop posting impossibilities as if they are solutions.

[Bored chemist]

At that point in the climb a serious error like cutting off the fuel to both engines is almost certain to be unrecoverable. So suicide is quite possible, just like the Airbus into the alps atrocity. One person at the end of their tether may have just snapped and said f*#k it, I've had enough- no one knows what is going on inside another person's head. Without detailed info we are all just speculating but the fact that no aircraft were grounded or extra inspections required suggests to me that the investigators knew quickly that the aircraft itself was not to blame. Despite Boeing's well documented problems this particular aircraft has had a stellar reputation for over a decade with widespread use. 

- The FAA issued an advisory in 2018 warning of potential thermal cycling damage to the microprocessor controlling these switches; but it wasn't mandatory, and Air India didn't perform the recommended inspections.

See more on this via the following Copilot link - near the end of the conversation.
https://copilot.microsoft.com/shares/tifJQgjwXJgRU4dsrPjkx

In spite of the name, "Copilot" is not a pilot and has no expertise or authority in this field.
Quoting it is like saying "I asked a ten year old child, and they said..."

[Bored chemist]

At that point in the climb a serious error like cutting off the fuel to both engines is almost certain to be unrecoverable. So suicide is quite possible, just like the Airbus into the alps atrocity. One person at the end of their tether may have just snapped and said f*#k it, I've had enough- no one knows what is going on inside another person's head. Without detailed info we are all just speculating but the fact that no aircraft were grounded or extra inspections required suggests to me that the investigators knew quickly that the aircraft itself was not to blame. Despite Boeing's well documented problems this particular aircraft has had a stellar reputation for over a decade with widespread use. 

- The FAA issued an advisory in 2018 warning of potential thermal cycling damage to the microprocessor controlling these switches; but it wasn't mandatory, and Air India didn't perform the recommended inspections.

See more on this via the following Copilot link - near the end of the conversation.
https://copilot.microsoft.com/shares/tifJQgjwXJgRU4dsrPjkx

In spite of the name, "Copilot" is not a pilot and has no expertise or authority in this field.
Quoting it is like saying "I asked a ten year old child, and they said..."

Re. "microprocessor controlling these switches"
Those switches are not controlled by a microprocessor.
They are controlled by a lever in the cockpit- operated by a human.