Air India crash

[onetrack]

Another media source, with added information ....

 

https://www.firstpost.com/explainers/air-india-plane-crash-ahmedabad-fuel-control-switches-movement-13904485.html

[jackc]

IF the aircraft had a Flight Engineer, the fuel switches would have been on his control panel and his responsibility.  
Pilots are for flying the aircraft, one of a Flight Engineers job is to keep the plane running. 
Just my useless opinion……..

[Methusala]

Increased automation of essential controls in pursuit of greater fuel efficiencies leads to cat eating tail outcomes. Mk 1 brain still leads Ai solutions

Edited Wednesday at 08:27 PM by Methusala

[onetrack]

The part I find interesting is that according to the B787 drivers, both fuel switches cannot be switched off at once, unless both hands are used. The switch handles need to be lifted against spring pressure, to go through their locking gates. This applies whether you're selecting "run" or "cutoff" with the switch.

 

The drivers say it would require a person using both hands to switch both fuel switches to cutoff at the same time, as appears to be the case here. The fuel switch cutoff is instantaneous, the engine spools down immediately.

If the pilot or co-pilot, sitting in their seats, strapped in, tried to switch both fuel switches simultaneously, it would require some extreme body movement, to do so. 

If the switches were moved to cutoff, one after the other, quickly, with one hand, I would expect to see some yaw, as one engine shut down before the other. I see zero yaw on takeoff, the flight travelled smoothly in one direction only.

 

As the switches are electric-over-mechanical, with spring pressure at the fuel valves holding the valves at the position they're set at (i.e., a power failure does not change the valve position), then the conclusion must be that electric power was supplied to the fuel valves to activate them to the cutoff position - and both at the same time.

 

How that could possibly happen if the switches weren't activated in the cockpit, has to be the main focus of the investigation, now. There is talk that the preliminary report, due tomorrow, will not reveal why the fuel valves were in the cutoff position - only that it happened, and much further investigation is going to be required, before the reason they were in that position, is found.

 

 

Edited Thursday at 01:41 AM by onetrack

[facthunter]

They are Lever-Latch switches. You can't just accidently flick them. They have to be LIFTED first.  Jackc I've flown 2  (Jet) types with flight engineers. Sometimes an engine is shut down during taxi to  the terminal to avoid excess brake use and after Parking also and the PF  does that..

  This was posted before the one above was able to be read by me.  The switches would be accessible as they are closer to the Pilot than the throttles and they can easily be in full forward from both seats when restrained by the seat belts  with seats in normal position.  Nev

Edited Thursday at 01:49 AM by facthunter

[facthunter]

The switches Could NOT Possibly Move by themselves.  Nev

[Roundsounds]

32 minutes ago, onetrack said:

The part I find interesting is that according to the B787 drivers, both fuel switches cannot be switched off at once, unless both hands are used. The switch handles need to be lifted against spring pressure, to go through their locking gates. This applies whether you're selecting "run" or "cutoff" with the switch.

 

The drivers say it would require a person using both hands to switch both fuel switches to cutoff at the same time, as appears to be the case here. The fuel switch cutoff is instantaneous, the engine spools down immediately.

If the pilot or co-pilot, sitting in their seats, strapped in, tried to switch both fuel switches simultaneously, it would require some extreme body movement, to do so. 

If the switches were moved to cutoff, one after the other, quickly, with one hand, I would expect to see some yaw, as one engine shut down before the other. I see zero yaw on takeoff, the flight travelled smoothly in one direction only.

 

As the switches are electric-over-mechanical, with spring pressure at the fuel valves holding the valves at the position they're set at (i.e., a power failure does not change the valve position), then the conclusion must be that electric power was supplied to the fuel valves to activate them to the cutoff position - and both at the same time.

 

How that could possibly happen if the switches weren't activated in the cockpit, has to be the main focus of the investigation, now. There is talk that the preliminary report, due tomorrow, will not reveal why the fuel valves were in the cutoff position - only that it happened, and much further investigation is going to be required, before the reason they were in that position, is found.

 

 

There’s a lot of inertia in those large fans, the time taken to move both switches to cutoff would be less than a couple of seconds. There maybe be little to no discernible yaw. It ja also possible to use one hand to move both to cuttoff. 

[facthunter]

Not really much Inertia compared to the thrust they generate in thew FAN section.. AT V2 you have to get full  opposite rudder in pretty quickly or you will turn more than permitted to fail the exercise.  As the speed increases you can reduce the rudder. NO aileron applied(or differential spoiler). A Staggered cut off WOULD definitely show, even as  a small delay. The Thrust is gone  when the fuel flow stops, essentially.  Nev 

[Roundsounds]

42 minutes ago, facthunter said:

Not really much Inertia compared to the thrust they generate in thew FAN section.. AT V2 you have to get full  opposite rudder in pretty quickly or you will turn more than permitted to fail the exercise.  As the speed increases you can reduce the rudder. NO aileron applied(or differential spoiler). A Staggered cut off WOULD definitely show, even as  a small delay. The Thrust is gone  when the fuel flow stops, essentially.  Nev 

I would agree with those comments on other Boeing types, however the B787 gust / asymmetry correction would mask the minor stagger in asymmetric thrust caused by the minute delay in fuel cutoff. 

Edited Thursday at 03:23 AM by Roundsounds

[facthunter]

Yes, but that should ALSO show on the FDR.  It's usually done by the yaw damper, (gyro stabilised)  on  the rudder  (YAW)and would probably show visually as well. Planes with marked wing sweep back usually have Yaw Dampers for other reasons. This is utilised in the engine failure case until flap is retracted to keep straight automatically. Nev

[Thruster88]

2 hours ago, onetrack said:

 

 

As the switches are electric-over-mechanical, with spring pressure at the fuel valves holding the valves at the position they're set at (i.e., a power failure does not change the valve position), then the conclusion must be that electric power was supplied to the fuel valves to activate them to the cutoff position - and both at the same time.

 

How that could possibly happen if the switches weren't activated in the cockpit, has to be the main focus of the investigation, now. There is talk that the preliminary report, due tomorrow, will not reveal why the fuel valves were in the cutoff position - only that it happened, and much further investigation is going to be required, before the reason they were in that position, is found.

 

 

 

The POSITION of the fuel cut off switches is recorded by the FDR. There has been no talk of any other faults. Seems like an open and shut case.

[onetrack]

The "talk of other faults", is what is missing at present. The AAIB preliminary report is likely to be somewhat disappointing, and declaring an open and shut case at any preliminary report is quite likely not ideal, as deeper investigation takes place, that often finds subtle or unrecorded factors in play. 

What if the fuel cutoff switches are recorded by the FDR as being untouched by the crew, in "run" position, but the fuel supply to the engines was found to be shut off, in contravention to the switch position? That would mean a much more intensive search to find the precise reason for the fuel starvation.

[Roundsounds]

28 minutes ago, onetrack said:

The "talk of other faults", is what is missing at present. The AAIB preliminary report is likely to be somewhat disappointing, and declaring an open and shut case at any preliminary report is quite likely not ideal, as deeper investigation takes place, that often finds subtle or unrecorded factors in play. 

What if the fuel cutoff switches are recorded by the FDR as being untouched by the crew, in "run" position, but the fuel supply to the engines was found to be shut off, in contravention to the switch position? That would mean a much more intensive search to find the precise reason for the fuel starvation.

Completely independent systems, cannot result in a dual engine failure. 

[Roundsounds]

2 hours ago, facthunter said:

Yes, but that should ALSO show on the FDR.  It's usually done by the yaw damper, (gyro stabilised)  on  the rudder  (YAW)and would probably show visually as well. Planes with marked wing sweep back usually have Yaw Dampers for other reasons. This is utilised in the engine failure case until flap is retracted to keep straight automatically. Nev

The B787 has a very advanced asymmetry correction system which becomes active above 60KIAS. Once airborne you could take your feet off the rudder pedals, fail an engine and the flight control system will compensate for the asymmetry. 

[kgwilson]

The physical action of moving a switch from on to off where computers control everything just means an electronic instruction has been passed to the computer controlling the fuel supply to tell the system to shut off the fuel. The physical process is purposely made difficult to prevent accidental activation. If somewhere in the system amongst the billions of transistors present on thousands of chipsets a software malfunction somehow erroneously thought it was instructed to shut off the fuel to the engines nothing could have been done to prevent it.

[onetrack]

There is nothing in the information coming out that says the fuel cutoff switches were actually moved. All that has been stated, is that the investigation is "focusing on the fuel switches".

 

No doubt the investigation is carefully studying the maintenance records and interrogating those who last worked on the aircraft. It is a worrying sign that falsified and inadequate aviation records have been provided by Air India Express staff previously.

[facthunter]

 Not directly relevant to this specific accident.  Most of these systems self identify a fault and are essentially Fail safe. Most of you are indulging in "what ifs" if you are not very familiar with this aircraft and it's specific systems Logic. Plus as time goes on more wild suggestions emerge to confuse things. One thing is lever lock switches do not move themselves and self activation of such a vital function of fuel flow to 2 ENGINES AT ONCE SHOULD BE COMPLETELY  regarded as not very likely.. Nev

Edited Thursday at 06:55 AM by facthunter

[kgwilson]

Not very likely does not mean impossible. I spent 30 years in  the computer industry & programs thought to be fail safe did things that they were never programmed to do. With multiple systems checking each other with fail over processes and fail safe logic there should be no way that things like this could happen.Very highly unlikely but not impossible.

[BrendAn]

28 minutes ago, kgwilson said:

Not very likely does not mean impossible. I spent 30 years in  the computer industry & programs thought to be fail safe did things that they were never programmed to do. With multiple systems checking each other with fail over processes and fail safe logic there should be no way that things like this could happen.Very highly unlikely but not impossible.

 

[BrendAn]

Imagine ai tech in your aircraft 

[facthunter]

They CAN be hacked they say.  Aeroplanes are special cases with computer function and redundancy  in many ways is more a part of Aviation Philosophy perhaps than most other engineering . I've had computer experts  express the views you have. way back.  I'm a Sceptic myself A faulted system is rejected and reverts to another MODE or is selected to an over ride.. Faulty LOGIC should be quickly rectified. Failing to anticipate a possibility is more likely in a very new concept than a proven  one.  A Human  Factors element falls into that category of where do you stop? .  Mechanical or hydraulic systems fail also. statistically Commercial Jet travel is by far the safest Way to get anywhere even though many in the game KNOW things are not as Good as they could be due to Laxety and cost cutting  Nev

[facthunter]

Commercial Aviation is not in the EXPERIMENTAL category.  Nev

[BrendAn]

6 minutes ago, facthunter said:

They CAN be hacked they say.  Aeroplanes are special cases with computer function and redundancy  in many ways is more a part of Aviation Philosophy perhaps than most other engineering . I've had computer experts  express the views you have. way back.  I'm a Sceptic myself A faulted system is rejected and reverts to another MODE or is selected to an over ride.. Faulty LOGIC should be quickly rectified. Failing to anticipate a possibility is more likely in a very new concept than a proven  one.  A Human  Factors element falls into that category of where do you stop? .  Mechanical or hydraulic systems fail also. statistically Commercial Jet travel is by far the safest Way to get anywhere even though many in the game KNOW things are not as Good as they could be due to Laxety and cost cutting  Nev

I don't have a view yet. Just posted something quite startling if it's true.

[facthunter]

Unless you go with Musk or in a submersible. . Regular Inspections and mandated checks help make Aviation safe, Airlines lose their AOC. Types are grounded extra training  required Pilots and others are GAOLED. Nev 

[spacesailor]

Just like the English " DH Comet " three crashed .

Then after a short inquiry,  they went back into service .

Only to be grounded for design faults and build faults. 

spacesailor