[mxplxxx (OP)]

As a matter of interest, what primary source made you think that the pumps were switched off? All the reports I have read (including the cockpit conversation between the pilots) refer to two cutoff switches, not eight pump switches.
 

I didn't think the pumps were turned off. It was just a possibility I had not initially considered (it was not mentioned in the preliminary report). And, given that the statuses of the pumps at the time of the crash were not provided in the report, it was worth considering. BTW the physical status of the cutoff switches at the time of the crash is not available. The reports statement that the cutoff switches physically set to CUTOFF is not verifiable.   A CUTOFF request can come via the FADEC and to both engines simultaneously. i.e. a software error may have caused the crash.

[paul cotter]

Someone flipped the switches to the cutoff position, initiating the disaster- I don't know how you cannot understand this simple fact. When the switches were returned to their run position the engines began their re-light sequence. This is all we know at this stage.

[Bored chemist]

The reports statement that the cutoff switches physically set to CUTOFF is not verifiable. 

One of the guys in the cockpit said they were.
The FDR agreed.
Sadly, the crash also acts as evidence for this.

I'm still waiting for you to answer this:
And again....
If the fuel pumps were not pumping/ valves were shut, how did the plane take off?
Magic?
The power of suggestion?
Carried aloft on the hand of a genie?
A spectacular display of synchronised flatulence?

What is your answer?

[alancalverd]

A CUTOFF request can come via the FADEC and to both engines simultaneously.

but it didn't. The cutoff commands were given sequentially. And the FADECs are independent, each commanded by the independent "throttle" settings (the "throttle" levers on a complex engine don't directly control the air intake, but tell the propulsion system how much power the pilot wants from each engine - the name is a convenient anachronism because we all learn to fly with a simple piston engine and fixed-pitch propellor, and the primary power control looks pretty much the same from there onwards).   

[mxplxxx (OP)]

A CUTOFF request can come via the FADEC and to both engines simultaneously.

but it didn't. The cutoff commands were given sequentially. And the FADECs are independent, each commanded by the independent "throttle" settings (the "throttle" levers on a complex engine don't directly control the air intake, but tell the propulsion system how much power the pilot wants from each engine - the name is a convenient anachronism because we all learn to fly with a simple piston engine and fixed-pitch propellor, and the primary power control looks pretty much the same from there onwards).   

I am suggesting a cause of the crash. You are talking about normal operation. I believe the FADEC handles downstream cutoff commands, and a possible cause of the crash is a FADEC malfunction. The throttle will not turn off the engine. Not sure where you got that from my posts?

So, the Copilot notices the engines have stopped (FADEC malfunction is a possible cause). Copilot then asks the pilot if he has cutoff the engines. Pilot says no. The Pilot subsequently toggles the engines Off/On via the cutoff switches in a failed attempt to restart the engines (but of course this may not work if the engines have already been turned off via a FADEC malfunction).

[paul cotter]

NO. When thrust was lost one of the pilots discovered the switches were in cutoff mode after checking for other faults(no one would have expected the switches to be in the wrong state for flight- it's probably the last thing one would check). The switches were then sequentially returned to "run" and the relight cycles began. This is what the data recorder indicates and there was no "toggling" of the switches. Quite apart from these known facts the idea that the two FADEC units experienced identical synchronised faults and identical synchronised recoveries is preposterous. Get real.

[alancalverd]

I believe the FADEC handles downstream cutoff commands, and a possible cause of the crash is a FADEC malfunction.

Far be it from me to question your faith, my friend, but the probability of two FADECs independently deciding to each cut off their engines, not simultaneously but within a couple of seconds of each other, and in such a manner that both engines could be restarted by simply flipping the manual cut switches, seems very close to zero. Many would call it a miracle.

Fortunately aircraft do not rely on faith to fly, but mechanical and electrical engineering embodiments of elementary physics and common sense.

I do hope you are wrong, because Acts of God are not insurable.

[mxplxxx (OP)]

I believe the FADEC handles downstream cutoff commands, and a possible cause of the crash is a FADEC malfunction.

"the probability of two FADECs independently deciding to each cut off their engines,

Wouldn't happen in normal circumstances but these are not normal circumstances. Computer software is invariable organised in hierarchies. So, there would almost certainly be a parent object for the two Cutoff switch software objects that could maybe do a full shutdown: first one engine and then the next.

[alancalverd]

The circumstances were entirely normal, the only difference being that one of the pilots (probably the captain) actuated both fuel cutoff switches at some point in the takeoff run.

Folk have been designing aircraft for long enough to ensure that the operation of the two cutoffs, like the FADECs, is entirely independent from switch to valve. There is never a requirement for simultaneous or autosequenced shutdown of both engines, and every reason to ensure that it is not actually possible.

The reason that most piston engines still rely on dual magneto ignition is to ensure that, once started, any and all  engines will run until the fuel is cut off regardless of the state of the rest of the electrical system. The same design philosophy applies to complex passenger jets, made simpler by the continuous combustion process.

[Bored chemist]

This

. Computer software is invariable organised in hierarchies.

seems to be a hallucination of yours.

Also, what would be the circumstances where you would call the "automatically shut down both engines during the takeoff stage of flight" subroutine?

[mxplxxx (OP)]

The circumstances were entirely normal, the only difference being that one of the pilots (probably the captain) actuated both fuel cutoff switches at some point in the takeoff run.

Folk have been designing aircraft for long enough to ensure that the operation of the two cutoffs, like the FADECs, is entirely independent from switch to valve. There is never a requirement for simultaneous or autosequenced shutdown of both engines, and every reason to ensure that it is not actually possible.

The reason that most piston engines still rely on dual magneto ignition is to ensure that, once started, any and all  engines will run until the fuel is cut off regardless of the state of the rest of the electrical system. The same design philosophy applies to complex passenger jets, made simpler by the continuous combustion process.

From Copilot:
"In piston engines, dual magnetos mean each cylinder is fired by two ignition sources, eliminating single-point failure. In jet turbines, particularly high-bypass turbofans like those on the Dreamliner, the continuous combustion process is sustained as long as airflow and fuel are present?making the engine inherently resilient once ignited. But unlike magneto-driven systems, FADEC (Full Authority Digital Engine Control) overlays software logic atop the physical system, introducing potential epistemic blind spots."

[Bored chemist]

The circumstances were entirely normal, the only difference being that one of the pilots (probably the captain) actuated both fuel cutoff switches at some point in the takeoff run.

Folk have been designing aircraft for long enough to ensure that the operation of the two cutoffs, like the FADECs, is entirely independent from switch to valve. There is never a requirement for simultaneous or autosequenced shutdown of both engines, and every reason to ensure that it is not actually possible.

The reason that most piston engines still rely on dual magneto ignition is to ensure that, once started, any and all  engines will run until the fuel is cut off regardless of the state of the rest of the electrical system. The same design philosophy applies to complex passenger jets, made simpler by the continuous combustion process.

From Copilot:
"In piston engines, dual magnetos mean each cylinder is fired by two ignition sources, eliminating single-point failure. In jet turbines, particularly high-bypass turbofans like those on the Dreamliner, the continuous combustion process is sustained as long as airflow and fuel are present?making the engine inherently resilient once ignited. But unlike magneto-driven systems, FADEC (Full Authority Digital Engine Control) overlays software logic atop the physical system, introducing potential epistemic blind spots."

Why are you still quoting the over-imaginative  10 year old?

[alancalverd]

Because it agrees with me!

The great thing about software is its repeatability. If you really do have a bug that shuts down both engines sequentially when the pilot has commanded full power, you'd expect this to happen every time any 787 enters the runway. Not a great selling point for what seems to be a very popular machine.

[mxplxxx (OP)]

Because it agrees with me!

The great thing about software is its repeatability. If you really do have a bug that shuts down both engines sequentially when the pilot has commanded full power, you'd expect this to happen every time any 787 enters the runway. Not a great selling point for what seems to be a very popular machine.

,MORE LIKELY  A MECHANICAL FAILURE THAT SCRAMBLES THE SOFTWARE OR THAT THE SOFTWARE DOESNT HANDLE WELL.( AS PER 737 MAX CRASH ).

[alancalverd]

AHA! A mechanical failure that causes a software failure that switches off two hardware switches sequentially in such a manner that they can be reset manually, at which point the engines restart, sequentially. And pigs might fly. Or was it unicorns?

The 737 debacle was a predictable hardware failure with an available manual override that the pilots had not been trained to use.

[mxplxxx (OP)]

The 737 debacle was a predictable hardware failure with an available manual override that the pilots had not been trained to use.

From Copilot: "That assertion oversimplifies a deeply layered failure chain. The 737 MAX crashes weren't just about a "predictable hardware failure" or a missed manual override. They were the result of systemic design flaws, regulatory lapses, and inadequate pilot training, all converging under high-stress conditions."

[mxplxxx (OP)]

AHA! A mechanical failure that causes a software failure that switches off two hardware switches sequentially in such a manner that they can be reset manually, at which point the engines restart, sequentially. And pigs might fly. Or was it unicorns?

No, you are not paying attention.  In response to a pilot setting a engine CUTOFF switch to OFF, the FADEC software closes an Engine Fuel Shutoff Valve (EFSOV). A fault in this software could easily be interpreted as a Close all Engines command by FADEC. If this the case, the pilots will not be aware it is so, and the Cutoff switches in the cockpit remain set to RUN. In an attempt to restart the engines, the Pilot has likely toggled the switches from RUN to OFF and BACK to RUN again. OIIIINK

[alancalverd]

Fuel cutoff has nothing to do with FADEC. It is necessarily an independent and overriding function since one of its uses is to isolate an engine that is not responding correctly to its FADEC.

FADEC cannot "close all engines"  since each engine has an independent FADEC commanded only by its throttle.

[alancalverd]

Copilot is again mirroring what it thinks you would like to read.

The 737 hardware failure (inoperative angle of attack sensor) was so predictable (it can happen to anyone on any aircraft) that Boeing offered a majority voting system as an option, which was not installed in the fatal incident planes.

There was no case of "missed" manual override as the pilots had never been trained to override the auto-trim and were almost certainly unaware that it could be done. The presumption was that you could transition directly from 737 to 737MAX because the peculiar departure characteristic of the MAX had been compensated by the auto-trim to prevent excessive AOA on rotation. The override can be demonstrated and taught on a simulator but 

MCAS was intended to mimic the flight behavior of the previous Boeing 737 Next Generation. The company indicated that this change eliminated the need for pilots to have simulator training on the new aircraft.

[mxplxxx (OP)]

Copilot is again mirroring what it thinks you would like to read.

The 737 hardware failure (inoperative angle of attack sensor) was so predictable (it can happen to anyone on any aircraft) that Boeing offered a majority voting system as an option, which was not installed in the fatal incident planes.

There was no case of "missed" manual override as the pilots had never been trained to override the auto-trim and were almost certainly unaware that it could be done. The presumption was that you could transition directly from 737 to 737MAX because the peculiar departure characteristic of the MAX had been compensated by the auto-trim to prevent excessive AOA on rotation. The override can be demonstrated and taught on a simulator but 

MCAS was intended to mimic the flight behavior of the previous Boeing 737 Next Generation. The company indicated that this change eliminated the need for pilots to have simulator training on the new aircraft.

Only partly explained. Here is a full explanation. https://copilot.microsoft.com/shares/mjBvnvCP7TxLrLxUnsXxC
btw Boeing was fined $2.5 billion in a settlement with the U.S. Justice Department related to the 737 MAX crashes