Air India crash

[Garfly]

3 minutes ago, kgwilson said:

I still reckon the system shut the fuel off as it got an instruction from some other part of the system that the valves were to be closed, so that's what it did.

I suppose that such a theory could fit with the reported CVR dialogue. (Along the lines of:  "Why did you do that?" / "I didn't do it!")

[facthunter]

I understand that and I should have Bracketed the words. I Bob. 

 kgw  What You" reckon" would be one of the most unlikely systems logic you could Imagine. Pilots wouldn't wear such a possibility.

Auto feather does exist on a lot of turbo props. but the Basis of that is usually a Torquemeter .Auto feather permits better climb performance where  windmilling prop drag can be more than Max thrust. Auto feather is not applied to the second failure  IF it happened. for obvious reasons. Nev

[kgwilson]

So if neither pilot actually moved the switches how did the fuel then get cut off?

[Thruster88]

55 minutes ago, Garfly said:

I suppose that such a theory could fit with the reported CVR dialogue. (Along the lines of:  "Why did you do that?" / "I didn't do it!")

It is unfortunately plausible that the pilot who asked the question "why did you cut off" was the... 

 

I think if there was any doubt about how the data recorders get fuel cutoff switch position or data it would be mentioned in the report.

 

Robinson Helicopter Company now fit as standard equipment in the r66 a cockpit camera system. It was used successfully in an Australian accident that would have otherwise most likely not have been solved. Perhaps such a system should be added to fitted to all aircraft. 

https://www.atsb.gov.au/publications/investigation_reports/2025/report/ao-2023-051

 

[facthunter]

The Lever Latch switch cannot be accidently moved either way. The #1 followed by #2  after brakes parked  is done at every shutdown. The uncommanded shut down of Both engines at low altitude, take off Power and gear still not retracted would be so dire as to require protection. Why wasn't the Gear retracted?  It's done on a call of "Positive climb" by the PNF and usually initiated by 150 ft. The rotation and initial climb was "Normal". while the gear position didn't CAUSE the crash there appears to be a deviation from Normal ops at that point.  Nev

[IBob]

I think folk need to read and digest the whole Interim report to clear away some of the assertions. 
Some Boeings were fitted with switches without the lever latches. Very unlikely in this case but not impossible.
As for retracting the undercarriage: it seems the RAT deployed almost immediately after rotation, with the engines commencing to shut down, after which they were fighting for their lives. They had no 'positive climb'. 

[IBob]

The media at large have jumped on 'the fuel was turned off' as one would expect.

That leaves us with two possibilities:
1. The fuel levers/switches were indeed turned off. 

2. Something downstream of those switches saw them as being turned off.
Both possibilities need to be investigated as far as is possible. And for 2, it becomes very important to know where the FDR gets it's info on those switches. Because to investigate possibility 2 requires an inspection of everything from the switches to where the FDR picks up that info.
Here I am guessing, but after years of process control work, including setting up a great deal of system monitoring and data logging, I would be surprised if the FDR is looking at the actual outputs from the lever switches. It is far more likely to be looking at some register in the automation that holds (or should hold) the state of the switches. In my opinion........

[Roundsounds]

3 hours ago, kgwilson said:

I still reckon the system shut the fuel off as it got an instruction from some other part of the system that the valves were to be closed, so that's what it did.

Cannot happen to both engines at the same time (or within 1 sec as per the report). 
All systems associated with the engines are completely independent. It’s like suggesting a couple of PC21s flying in close formation both flame out at the same time due to a system fault in one aircraft. 

[Roundsounds]

13 minutes ago, IBob said:

The media at large have jumped on 'the fuel was turned off' as one would expect.

That leaves us with two possibilities:
1. The fuel levers/switches were indeed turned off. 

2. Something downstream of those switches saw them as being turned off.
Both possibilities need to be investigated as far as is possible. And for 2, it becomes very important to know where the FDR gets it's info on those switches. Because to investigate possibility 2 requires an inspection of everything from the switches to where the FDR picks up that info.
Here I am guessing, but after years of process control work, including setting up a great deal of system monitoring and data logging, I would be surprised if the FDR is looking at the actual outputs from the lever switches. It is far more likely to be looking at some register in the automation that holds (or should hold) the state of the switches. In my opinion........

The AAIB report states one of the crew observed the Fuel Control Switches in the Cutoff position and questioned the other crew member. The switch position is tracked by the EAFR.

[IBob]

33 minutes ago, Roundsounds said:

The AAIB report states one of the crew observed the Fuel Control Switches in the Cutoff position and questioned the other crew member. The switch position is tracked by the EAFR.

No it doesn't Roundsounds. What it actually says is

 

"In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff.
The other pilot responded that he did not do so."

It says nothing about anyone observing that switches were in cutoff position. Maybe he saw the valves off in a panel display???

And you're missing the point about the EFAR, but I don't know how to explain it any clearer except to repeat that it quite possibly logs what the automation thinks the switch positions are......not the actual inputs from the switches. And that's a very important difference.

Edited Saturday at 08:08 AM by IBob

[Bosi72]

According to info from other forum, this is the switch

https://octopart.com/4tl837-3d-honeywell-25749542

 

 

There are about 8 wires going out of switch and I believe there would be confirmation from multiple sources that the switch was actually physically moved, rather than controlled by some computer.

 

Also one pilot asked another why cutoff the switch, etc...

 

The question remains: why ? 

 

I hope that will be revealed in the Final report.

 

 

 

[facthunter]

Of Course that plane had positive climb. You can see it in the Vids. Check what altitude it reached.  The ONLY way  to do the cut off is to move the switch. The response is to put them back on and try a relight for which there was not enough time.  The RAT would deploy with no electrical Power There would be no program to cut off BOTH Engines in such circumstances. I think we can be sure of that as it wouldn't get certification. Nev

Edited Saturday at 08:34 AM by facthunter

[Roundsounds]

34 minutes ago, IBob said:

No it doesn't Roundsounds. What it actually says is

 

"In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff.
The other pilot responded that he did not do so."

It says nothing about anyone observing that switches were in cutoff position. Maybe he saw the valves off in a panel display???

And you're missing the point about the EFAR, but I don't know how to explain it any clearer except to repeat that it quite possibly logs what the automation thinks the switch positions are......not the actual inputs from the switches. And that's a very important difference.

The only way the person querying the FCS position would know they were in the Cutoff position would be to observe the switch position. There are no indications of fuel valve positions.
Again, I point out these systems are in no way connected to each other. The chances of both systems experiencing the same fault within 1 second of each other are too remote. 

[Blueadventures]

Seems that 3 secs and a bit after liftoff the cutoffs happened; I'd expect the flying officer would have his hands on the yoke and throttle; therefore the only person to operate anything else is the other pilot in the cockpit.  So looking like that person is the suspect at present at a guess.

[BrendAn]

7 hours ago, Thruster88 said:

There are switches with the same function in every aircraft, including the type you are now flying.

I mean why would there 2 fuel cutoff switches so easy to access. I thought there would be some sort of safety lockout

[IBob]

52 minutes ago, Roundsounds said:

The only way the person querying the FCS position would know they were in the Cutoff position would be to observe the switch position. There are no indications of fuel valve positions.
Again, I point out these systems are in no way connected to each other. The chances of both systems experiencing the same fault within 1 second of each other are too remote. 

Roundsounds, I watched part of an analysis that included pics from a flight simulator. There was an active display showing the fuel valve/s status.
And unless you go through the switches and logic, including the power to those, you cannot say there is no connection between the two systems. In a perfect world, yes. But given what happened, I would not blithely assume that. I would check.

[danny_galaga]

37 minutes ago, BrendAn said:

I mean why would there 2 fuel cutoff switches so easy to access. I thought there would be some sort of safety lockout

It's a mechanical lockout, as per this informative video from Juan Brown 

 

https://youtu.be/wA_UZeHZwSw?si=ZqlOq3FWp9YnY8Fj

[jackc]

Surely, since the Aircraft was in take off configuration at full thrust, the computer management system, would not allow a manual switch fuel cutoff to work,  those switches would be locked out in the  control system, because of the aircraft configuration at the time.

The  only exception could be IF a motor blew up and a heap of parameters showing same, then the fuel should automatically shut off, anyway? 
I smell a big rat, in all of this……..

[Roundsounds]

17 minutes ago, jackc said:

Surely, since the Aircraft was in take off configuration at full thrust, the computer management system, would not allow a manual switch fuel cutoff to work,  those switches would be locked out in the  control system, because of the aircraft configuration at the time.

The  only exception could be IF a motor blew up and a heap of parameters showing same, then the fuel should automatically shut off, anyway? 
I smell a big rat, in all of this……..

Nope

[Roundsounds]

49 minutes ago, IBob said:

Roundsounds, I watched part of an analysis that included pics from a flight simulator. There was an active display showing the fuel valve/s status.
And unless you go through the switches and logic, including the power to those, you cannot say there is no connection between the two systems. In a perfect world, yes. But given what happened, I would not blithely assume that. I would check.

I don’t know what you watched, but I can guarantee you there are no indications of fuel valve positions in a B787 displayed during takeoff. 

[facthunter]

Once the aircraft has rotated there's NO reason to have the PF's hand anywhere near the throttles. You are past the accelerate-stop decision point. Fuel tank valving has nothing to do with engine cut off switches.    Nev

[onetrack]

Nev - There is a fuel supply valve in the fuel line to the engine that is part of the fuel cutoff system. Activating the fuel cutoff toggle switch in the cockpit closes contacts that sends an electrical signal to the engine ECU, which then sends an electrical signal to the solenoid that activates the spring-pressure loaded HPSOV (High Pressure Shut Off Valve).

 

The HPSOV must be electrically activated to move to either position, On or Off, because the spring-loaded detents hold the HPSOV in whatever position the last electrical signal told it to do. This is Boeings fail-safe system for the HPSOV.

 

As it is obvious from the preliminary report, the fuel cutoff switches were moved in the cockpit - and the crew voices confirm that.

As the PF is fully concentrating on the lift-off, and has both hands on the yoke, it seems it was the PNF who moved the switches. I think that the reason why he did so, may never be found.

As I understand it, the PNF is carrying out a purely monitoring job, so he has little reason to operate important flight controls - unless he saw an emergency.

But no pilot should ever take any drastic engine control measures at takeoff, 400 feet is the minimum critical altitude mentioned in all manufacturer and training information.

 

 I feel there's a Boeing design failure here that allows engine fuel cutoff switches to be activated at under 400 feet.

 

The interesting part is that the fuel cutoff switching system is not mentioned in the B787 Thrust Management System, because it is designed only to used on the ground at shutdown - or in an emergency, such as an engine fire.

 

But no pilot would ever shut down an engine that's on fire, when they're at a critical altitude, so that critical altitude protection should now be written into the fuel cutoff switching system logic, to prevent a crash like this one happening again.

 

Boeing 787 Thrust Management System Explained

WWW.TRANSGLOBALTRAINING.COM

---

Discover how the advanced Thrust Management System in Boeing 787 enhances safety, efficiency and reduces pilot workload

 

[jackc]

There may be a Boeing design fault, but there is a crew fault….NO Flight Engineer with a seperate control panel……

[pmccarthy]

I wonder whether a quick sharp blow, accidentally when removing hand from the throttles, could trip the two switches. Particularly if the detents were worn or somehow out of spec.

[facthunter]

Unlikely and BOTH of them? Flight engineers disappeared in the 80's, that's 40 years ago.  There's nothing for them to do in today's aeroplanes and they'd be Bored $#itless. They can also make mistakes and MISS others making them.  I share the Indian  Airpilots group warning against putting the Blame on the crew before it's finally assessed which may  still be a while yet. The only place a High PSV  would be located is after the Engine HIGH pressure pump probably in the engine fuel control unit ON the engine.  Nev