Mumbai: The Air India aircraft, which crashed soon after takeoff in Ahmedabad last month, might have suffered mechanical or power supply issues that could have led to the change in the position of the switches that feed fuel into the plane, experts said Saturday.
They also opined that the reasons for the change in fuel switch position will be known during further investigations.
The Aircraft Accident Investigation Bureau’s (AAIB) preliminary report has mentioned that fuel switches of engine 1 and 2 of the Boeing 787-8 aircraft were cut off within a gap of one second and later turned on before the crash June 12.
On June 12, the London-bound Boeing 787 Dreamliner began to lose thrust almost immediately after taking off from the Ahmedabad airport and ploughed into a medical college hostel, killing all but one of the 242 onboard and another 19 on ground in the deadliest aviation accident in a decade.
Federation of Indian Pilots (FPI) President and former Air India pilot Captain CS Randhawa said the position of the fuel switches can be changed only with a human interface.
These switches are spring-loaded and have a lock. If they have to be put into RUN position, then first, it has to be pulled out and move into the position, he said.
According to him, the switches are generally used in case there has been a flameout of both engines or the pilots have recycled the switches. “It is not clear from the preliminary report as to why the position of the switches was changed”, he said and added that there could also have been an interruption in the power supply.
“When the fuel control switch has to be cut off, the pilot flying will say, fuel control switch left, confirm. So, after the confirmation is made by the second pilot, the pilot monitoring will cut off (the switch).
“In this case, the first officer was taking off the aircraft and the captain was pilot monitoring. Now, did this transfer of controls take place between the captain and the first officer? It is not clear from the report at all,” he noted.
The fuel switches are below the throttles.
“Now, in case of a dual engine flameout, the auto-throttle switches are put off and fuel control switches are made to cut off and run. Basically, they reactivate,” he said.
A former Directorate General of Civil Aviation (DGCA) official said there was a change in the position of the fuel switches and the question is why it happened.
“Now, the investigation will lead in this direction to why this switch position changed, whether it was a mechanical failure, whether it was intentional or unintentional or anything else or if there was a problem… The question is also whether there was a software glitch and or not,” he said.
In the report, there is no mention on whether there was any malfunctioning of the fuel switches earlier.
A senior Boeing commander said it is not exactly clear from the preliminary report why the fuel switch was turned to CUTOFF from RUN position. The change might have happened inadvertently, he added.
According to a senior official, who has been part of various aircraft accident investigations, investigations in the coming months will help in ascertaining the reasons, including whether there were any mechanical issues, for the change in position of the fuel switches.
“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 01 sec.
“The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off.
“In the cockpit voice recording, one of the pilots is heard asking the other why did he cut off. The other pilot responded that he did not do so,” the report said.
PTI
