One pilot asked the other about fuel cutoff seconds before crash, says preliminary AI171 crash report
"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 preliminary report on the Air India crash said.
The report mentions that both engines of the Boeing 787-8 Dreamliner shut down one second apart shortly after takeoff. This caused the aircraft to lose altitude rapidly and crash near the boundary of Ahmedabad's Sardar Vallabhbhai Patel International Airport. Investigators have ruled out any bird strike or external damage, although the cause of the fuel cutoff remains under investigation.
According to the report, "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 cut off."
CCTV footage from the airport showed the Ram Air Turbine (RAT) deploying shortly after takeoff, indicating that power was lost early in the flight. "The CCTV footage obtained from the airport showed the Ram Air Turbine (RAT) getting deployed during the initial climb immediately after lift-off. No significant bird activity is observed in the vicinity of the flight path. The aircraft started to lose altitude before crossing the airport perimeter wall," the report added.
Further, the report said that data downloaded from the forward Enhanced Airborne Flight Recorder (EAFR) is being analysed in detail.
The report also stated that no immediate safety actions have been recommended for B787-8 aircraft or the GE GEnx-1B engines at this stage. However, investigators will continue to review more evidence, records, and information from relevant stakeholders.
Meanwhile, a 2018 safety warning from the United States Federal Aviation Administration (FAA) regarding a possible flaw in Boeing's fuel control switches has resurfaced as part of the investigation. The FAA had earlier warned that the locking feature on these switches, which prevents accidental engine shutdown, could become disengaged. However, it did not mandate corrective action.
"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 aeroplanes that the fuel control switches were installed with the locking feature disengaged. The airworthiness concern was not considered an unsafe condition that would warrant an airworthiness directive (AD) by the FAA," the report states.
"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," it added.
On 12 June this year, the London-bound Air India Boeing 787-8 crashed shortly after takeoff from Ahmedabad. The aircraft struck a hostel building at BJ Medical College, killing 241 of the 242 people on board. Among the victims was former Gujarat Chief Minister Vijay Rupani. The incident is among India's deadliest aviation disasters in recent times.
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