Known fuel switch issue not checked: FAA bulletin flagged part in 2018, Air India crash report shows

A known issue related to a fuel control switch locking flaw was never inspected on the Air India Boeing 787-8 aircraft involved in the recent crash, despite prior awareness flagged by U.S. aviation authorities, documents show.

The U.S. Federal Aviation Administration (FAA) had issued Special Airworthiness Information Bulletin (SAIB) No. NM-18-33 on December 17, 2018, warning of the potential disengagement of the fuel control switch locking feature. This advisory was based on operator reports involving Model 737 aircraft, where fuel switches were found with the locking mechanism disengaged.

Though the FAA did not deem the issue severe enough to warrant an Airworthiness Directive (AD), the design of the fuel control switches—including the same locking feature—also exists on other Boeing models, including the 787 series. The Air India aircraft in question, registered as VT-ANB, was fitted with the relevant part (4TL837-3D), the bulletin confirms.

According to Air India’s own submissions, the inspections suggested in the SAIB were not carried out, since the bulletin was advisory in nature and not mandatory. Maintenance records show that the throttle control module on VT-ANB was replaced in both 2019 and 2023. However, the airline clarified that these replacements were unrelated to the fuel control switch.

Notably, no defect has been reported regarding the fuel control switches on VT-ANB since 2023.

The development gains significance in light of the preliminary crash report, which confirmed that both engine fuel control switches transitioned to the “cutoff” position seconds after takeoff. One pilot was recorded asking, “Why did you cutoff?”—to which the other denied taking any action.

Investigators have not assigned blame, and no conclusion has been drawn on whether the transition was intentional, inadvertent, or due to a technical issue.