The investigation report says Air India did not carry out those inspections - prompting speculation that the accident could have been caused by faulty switches being flipped by accident. However, in an internal note seen by the BBC, the FAA has since reiterated its belief that the issue did not compromise safety.

The CEO of Air India sought to draw a line under rife speculation around the cause of last month's air disaster in Ahmedebad, saying the preliminary investigation had ruled out a mechanical cause for the crash.

A preliminary report about the fatal Air India crash resurfaced a 2018 Federal Aviation Administration notice about Boeing's engine fuel control switches.