Profoundly Weird

The initial Air India flight 171 probe is pointing to the engine fuel cutoff switches being thrown seconds after takeoff.

This raises a lot of questions.

As you can see, the switches are guarded on either side, and they are heavy switches requiring a fair amount of force to use.

This (very) strongly implies that this happened as a direct result of a deliberate action by either the pilot of the first officer.

The (very) preliminary is also (very) incomplete, further muddying the waters:

Guided by an opaque process that produced a preliminary report lacking basic details common to any competent accident investigation update, industry’s response to the June 12 crash of an Air India Boeing 787 is leaning heavily on precautions and reading the tea leaves of those with knowledge of the probe.

A preliminary report on Air India Flight 171 (AI 171), prepared by India’s Aircraft Accident Investigation Bureau (AAIB) and released early July 12, confirms a few key facts about the accident sequence. The most critical: Both of the 787’s engine fuel control switches “transitioned” from RUN to CUTOFF within about 1 sec. of each other, just after the aircraft rotated, investigators say. This immediately cut fuel to each GE Aerospace GEnx-1B engine.

But the report does not shed light on why or how the switches moved. The only conversation referenced in the report between the two pilots at the controls adds confusion where clarity is needed.

“In the cockpit voice recording [CVR], one of the pilots is heard asking the other why did he cut off,” the report states. “The other pilot responded that he did not do so.”

The switches, located in the throttle control module between the pilots, are designed to prevent accidental movement. They have fixed metal guards on either side and must be pulled out and then down over a gate before they can be toggled to stop fuel flow. The only reasons to touch them are for starting or stopping engines or troubleshooting an emergency.

There is no reason to move them 3 sec. after liftoff, as happened on AI 171, data gleaned from the aircraft’s enhanced airborne flight recorders (EAFR) shows.

………

Movement of the fuel cutoff switch in flight triggers the 787’s engine-indicating and crew-alerting system, which spotlights possible issues for pilots. The report does not reference this or any other flight deck alerts, cautions or warnings generated from engine startup to the last moments recorded on the EAFR—a span of about 22 min.

The report details no other information from the CVR—including discussions that would point to a potential technical fault, cockpit confusion or distraction or anything else that could shed light on the accident sequence.

………

Although the AAIB report does not discuss 787 system characteristics that could explain uncommanded or unintentional switch movement, it does note that inspections recommended in a December 2018 FAA special airworthiness information bulletin (SAIB) on a safety mechanism built into the switches were not done on the accident aircraft, VT-ANB. The SAIB revealed reports of installation problems with some 737 switches and recommended that operators inspect them and similarly designed switches on other Boeing models, including 787s. 

 I think that this is going to get a lot weirder before we see any clarity.