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Preliminary report into Air India crash released

(www.bbc.co.uk)
352 points cjr | 2 comments | 11 Jul 25 20:23 UTC | HN request time: 0.421s | source
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nottorp ◴[12 Jul 25 07:42 UTC] No.44540123[source]▶
Almost 400 comments and no avherald link for reference?

https://avherald.com/h?article=528f27ec

replies(1): >>44540922 #
potamic ◴[12 Jul 25 10:23 UTC] No.44540922[source]▶
> On Jul 12th 2025 (UTC) India's media report that the investigation is NOT focussing on a human action causing the fuel switches to appear in the CUTOFF position, but on a system failure. Service Bulletins by Boeing issued in year 2018 recommending to upgrade the fuel switches to locked versions to prevent inadvertent flip of the switches, as well as the FAA/GE issued Service Bulletin FAA-2021-0273-0013 Attachment 2 relating to loss of control issue (also see above) were NOT implemented by Air India. The stated MN4 computer with faulty soldering, that might weaken and lose contact due to the thermal stress after a number of cycles, interprets data and commands fuel metering valves - with the lost contact attaching the MN4 processor to the EEC intermittent electrical contact, loss of signal processing and engine control faults can occur. The SB writes under conditions for the SB: "An LOTC (Loss Of Thrust Control) event has occurred due to an EEC MN4 microprocessor solder ball failure." According to discussions in the industry it may be possible with the number of cycles VT-ANB had already completed, the solder balls were weakened sufficiently to detach the MN4 from the EEC momentarily due to loads during the takeoff rotation leading to the loss of control of thrust and shut down of the engines.

Still quite early in the investigation, and so many things to consider. I don't know why online communities have been so quick to gravitate towards the murder/suicide theory. I thought aviation enthusiasts of all people would want to keep an open mind until every other possibility is ruled out, however minuscule it might seem.

replies(5): >>44541015 #>>44541663 #>>44542123 #>>44542484 #>>44545021 #
VBprogrammer ◴[12 Jul 25 12:43 UTC] No.44541663[source]▶
My concern would be that the investigation in this case is more likely to be biased towards a system failure. Disgracing a major flag carrier is something very few regulars have the independence and courage to get away with.
replies(2): >>44542571 #>>44544545 #
1. nottorp ◴[12 Jul 25 15:06 UTC] No.44542571[source]▶
The way i read what avherald highlighted is that a part that the manufacturer said should be replaced wasn't and failed as the manufacturer said it will. So it would point to the airline maintenance right now.

What the bbc says is truncated and omits the info about the failing part, so people can point towards murder suicide because they don't have all the info.

Which is why you should always read avherald first...

replies(1): >>44544738 #
2. VBprogrammer ◴[12 Jul 25 20:08 UTC] No.44544738[source]▶
The avherald is reporting second hand reports of the Indian media. The EEC MN4 microcontroller is located on a control board on each engine. A dual failure seems improbable.

The fuel cutoff switches are of a similar design to the 737 and most other Boeing aircraft. A failure in that design seems less likely than the most charitable explanation, that the copilot inadvertently went into the wrong mode of muscle memory.

The interim report does mention the SIAB NM-18-33. If you read that document it specifically says that the fuel cut-offs were installed with the locking feature deactivated on some 737 aircraft. It's a pretty big leap to that causing this incident. Someone or some thing would still need to have touched the switches to move them.