AI171 preliminary probe: 2018 report flagged fuel switch concern, but said it wasn't 'unsafe'

MUMBAI: The preliminary report of Aircraft Accident Investigation Bureau (AAIB) into the June 12 Air India flight 171 crash in Ahmedabad refers to a serviceability bulletin on the Boeing-787's fuel control switch which indicates a potential equipment malfunction, but deemed it was not an unsafe condition.

The AAIB report mentioned that the fuel switches of engine one and two of the Boeing 787-8 Dreamliner aircraft were cut off within a gap of one second and later turned on before the crash.

Capt Sam Thomas, president of the Airline Pilots' Association of India, said: "The AAIB report refers to a serviceability bulletin concerning the fuel control switch gates, which indicates a potential equipment malfunction. The tone and direction of the investigation suggest a bias toward pilot error. ALPA categorically rejects this presumption and insists on a fair, fact-based inquiry."

What is the possible technical issue? The AAIB report refers to the 'Special Airworthiness Information Bulletin (SAIB) No. NM-18-33' issued by the US regulator, the Federal Aviation Administration (FAA), in Dec 2018. The bulletin is about the potential disengagement of the fuel control switch locking feature. The bulletin was issued after reports came in from operators of Boeing 737s that the fuel control switches were installed with the locking feature disengaged. The said fuel control switch design, including the locking feature, is similar on various Boeing airplane models, including the B787, the aircraft that crashed.

The FAA recommended: "Inspect the locking feature of the fuel control switch to ensure its engagement. While the airplane is on the ground, check whether the fuel control switch can be moved between the two positions without lifting up the switch. If the switch can be moved without lifting it up, the locking feature has been disengaged and the switch should be replaced at the earliest opportunity."

The AAIB report said: "The airworthiness concern was not considered an unsafe condition that would warrant an airworthiness directive (AD) by FAA. As per information from Air India, the suggested inspections were not carried out as the SAIB was advisory and not mandatory."