737 Max

[Beany]

This is interesting, from the report, page 6

The FAA issued Special Airworthiness Information Bulletin (SAIB) No. NM-18-33 on December 17, 2018, regarding the potential disengagement of the fuel control switch locking feature. This SAIB was issued based on reports from operators of Model 737 airplanes that the fuel control switches were installed with the locking feature disengaged. The airworthiness concern was not considered an unsafe condition that would warrant airworthiness directive
(AD) by the FAA.

The fuel control switch design, including the locking feature, is similar on various Boeing airplane models including part number 4TL837-3D which is fitted in B787-8 aircraft VT-ANB. As per the information from Air India, the suggested inspections were not carried out as the SAIB was advisory and not mandatory.

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.

[tim]

I was feeling better about this on the basis of it being pilot error not manufacturing defect, but now I see how easy those switches are to flick I'm not so much...

You can't flick them by accident. They have to be pulled out and lifted over a gate. It really looks like a deliberate action, one after the other a second apart.

[V8Granite]

There can’t be many situations where you need to easily access a way of cutting off your fuel supply.

Ruptured line, engine aflame, I wonder why some kind of interlock wasn’t the norm for these. Must be a reason.

For example even our big diesel pipes will have gated valves, not ball valves so they can’t be knocked closed or open by accident.

Planes are complicated beasts so hopefully the reason those type of switches are used will come to light.

Dave!