Air India crash

Actually, there seems to be further twist. There is an airworthiness inspection directive apparently for an inspection of the switches because some were incorrectly assembled and the locking did not work. But the AD was not compulsory, and it appears that AI did not do these inspections on this aircraft.

If the locking mechanism was not effective on this plane (Are they sufficiently undamaged to tell?), the blame can be distributed between the airline's maintenance and pilots and manufacturer and the FAA (their airworthiness certification and directives responsibility).

A news report stated that the cockpit voice recorder heard one pilot asking the other pilot why he switched off the fuel whereupon the other pilot said that he didn't. Might they have vibrated off?

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Originally Posted by JDNSW

Actually, there seems to be further twist. There is an airworthiness inspection directive apparently for an inspection of the switches because some were incorrectly assembled and the locking did not work. But the AD was not compulsory, and it appears that AI did not do these inspections on this aircraft.

If the locking mechanism was not effective on this plane (Are they sufficiently undamaged to tell?), the blame can be distributed between the airline's maintenance and pilots and manufacturer and the FAA (their airworthiness certification and directives responsibility).

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Yes, it didn't seem likely that someone would turn them off or not be seen doing it - an existing fault would also explain the conversation between the two pilots. But that hasn't stopped on-line "experts" saying that it was intentional and one of the pilots must have done it deliberately.

You would think that this would now mean that all of these planes will now be grounded whilst this issue is checked and fixed.

Yes, or at least the non-mandatory AD made mandatory.

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Originally Posted by JDNSW

Actually, there seems to be further twist. There is an airworthiness inspection directive apparently for an inspection of the switches because some were incorrectly assembled and the locking did not work. But the AD was not compulsory, and it appears that AI did not do these inspections on this aircraft.

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The prelim report says :

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The scrutiny of maintenance records revealed that the throttle control module was replaced on VT-ANB in 2019 and 2023.
However, the reason for the replacement was not linked to the fuel control switch. There has
been no defect reported pertaining to the fuel control switch since 2023 on VT-ANB.

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So that won't have been a factor.

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Originally Posted by JDNSW

Yes, or at least the non-mandatory AD made mandatory.

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Sorta puts it back on Boeing, and of course the various Safety Bureaus. Boeing, of course, cannot enforce any mandates, but they can stress the importance of any ADs. I'm not trying to hang them out to dry here*, but I'll bet they will come under scrutiny, given the lack of urgency shown in the MCAS matter. Watching to see if these ADs now become mandatory, for ALL Boeing aircraft with similar switches. Juan mentions that the 737 series has them. I wonder if they are a generic, or Boeing specific, item. One comment from a pilot I read suggested they should be moved to the overhead, and given an isolated location up there. Seems like a commonsense idea to me.

Juan also mentions the senseless speculation and AI slop around this incident. I mentioned before that there were many trying to piggyback on a tragedy for views and clicks. Juan is spot on. I am guilty of the speculation thing, which is human nature I guess, but not the self aggrandisement. I just hope the lessons here are learned by the entire industry.

* I'll bet many people are.

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Originally Posted by BradC

So that won't have been a factor.

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Which leaves pilot error or malfeasance, unless the fault appeared after the inspection. Hard to see it any other way. But, speculation. As Juan noted, we may never know for certain. But steps need to be taken to prevent a recurrence.

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Originally Posted by Tins

Which leaves pilot error or malfeasance, unless the fault appeared after the inspection.

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The "fault" identified in the AD is a manufacturing defect whereby the switch was not fitted with the guard to prevent it being toggled without lifting the handle. It can't just appear. That AD was also related to switches fitted to later model 737's. The fact those switches were also used on 787-8's prompted the "better check that also" but I can find no information on faulty switches actually being found on 787's. Regardless, the panel containing those switches was replaced twice on that aircraft, the first time being a year after the AD was issued.

There are plenty of previous accidents whereby the CVR has been used to correlate cockpit actions. Switches like those have a nice "click" and accident investigators are bloody good at identifying the slightest noise in the recording.

My opinion is the report as issued is written to specifically exclude any factor which may impact other aircraft (design & maintenance primarily) such that there are no actions required on the part of other parties (Boeing or airlines) and nothing more. I suspect they already have a pretty good idea what happened, but there's a lot of forensic investigation of the available data required to put the findings beyond reasonable doubt, so we'll have to wait a couple of years for the final report to really know.

If you haven't read the prelim report, you should. It's not long and it's written in a manner anyone with the slightest technical background would understand clearly.

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Originally Posted by BradC

The "fault" identified in the AD is a manufacturing defect whereby the switch was not fitted with the guard to prevent it being toggled without lifting the handle. It can't just appear.

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I was referring to Juan's comment re the switches perhaps not locking correctly.

Interesting. FYI.

https://youtu.be/CoTsvyA-bRw'si=mOPJVBg9HYELIMSG