What are the fuel switches at the centre of the Air India crash probe?
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A police officer standing in front of the wreckage of the Air India jet that crashed in Ahmedabad on June 12.
PHOTO: REUTERS
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NEW DELHI – The preliminary report from investigators probing the Air India crash that killed 260 people
Here are a few facts about the switches, their functions in the aircraft and their movements on the Air India flight.
What are fuel switches?
They are switches that regulate fuel flow into a plane’s engines.
They are used by pilots to start or shut down engines on the ground, or to manually shut down or restart engines if an engine failure occurs during a flight.
Aviation experts say a pilot would not be able to accidentally move the fuel switches that feed the engines.
But if moved, the effect would be immediate, cutting off engine power.
There are independent power systems and wiring for the fuel cut-off switches and the fuel valves controlled by those switches, according to US aviation safety expert John Cox.
Where are the fuel switches located?
The two fuel control switches on a Boeing 787, in Air India’s case equipped with two GE engines, are located below the thrust levers.
There are two modes: “cut-off” and “run”.
The switches are spring-loaded to remain in position. To change one from run to cut-off, a pilot has to first pull the switch up and then move it from run to cut-off or vice versa.
What happened on the fatal Air India flight?
According to the flight recorder, a few seconds after take-off, switches for both engines transitioned to cut-off from run one after another with a time gap of one second.
As a result, the engines began to lose power.
One pilot was 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.
Seconds later, the switches were flipped back to run, according to the preliminary report.
Both fuel control switches were found in the run position at the crash site, it said.
When fuel control switches are moved from cut-off to run while the aircraft is in flight, each engine’s control system automatically manages a relight and thrust recovery sequence of ignition and fuel introduction, the report said.
“No sane pilot would ever turn those switches off in flight,” especially as the plane is just starting to climb, US aviation safety expert John Nance said. REUTERS
