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Fuel to the engines of the Air India plane that crashed and killed 260 people last month appears to have cut off seconds after taking off, a preliminary report has found.
Switches in the cockpit that controlled fuel moved to a “CUTOFF” position, the report found.
It said: “The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of one second.
“The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cutoff.”
The Boeing 787 Dreamliner immediately began to lose thrust and sink, according to the report released by Indian aviation accident investigators into the world’s deadliest plane crash in a decade.
One pilot can be heard on the cockpit voice recorder asking the other why he cut off the fuel. “The other pilot responded that he did not do so,” the report said.
It did not identify which remarks were made by the flight’s captain and which by the first officer, nor which pilot transmitted “Mayday, Mayday, Mayday” just before the crash on June 12th.
The preliminary findings also do not say how the switch could have flipped to the cutoff position on the flight from Ahmedabad to London.
US aviation safety expert John Cox said a pilot would not be able to accidentally move the fuel switches that feed the engines. “You can’t bump them and they move,” he said.
Flipping to cutoff almost immediately cuts the engines. It is most often used to turn engines off once a plane has arrived at its airport gate and in certain emergency situations, such as an engine fire. The report does not indicate there was any emergency requiring an engine cutoff.
“At this stage of investigation, there are no recommended actions to Boeing 787-8 and/or GE GEnx-1B engine operators and manufacturers,” India’s Aircraft Accident Investigation Bureau said.
The report also found that at least five buildings were destroyed when Air India Flight 171 crashed into a densely populated residential area in Ahmedabad.
“The aircraft was destroyed due to impact with the buildings on the ground and subsequent fire,” the report said.
Nearly 30 people died on the ground after the plane crashed into a hostel for medical students, the Byramjee Jeejeebhoy medical college and civil hospital, outside the airport.
One section of the report explained how one of the engines was able to restart after transitioning to cutoff, but could not reverse the plane’s deceleration.
Engine 1’s core deceleration stopped, reversed and started to progress to recovery, the report says, while Engine 2 was able to relight but “could not arrest core speed deceleration”.
