An official report on the world’s deadliest aviation accident in a decade, seen by CNN, has answered one key question – but raised others.

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.

Boeing fuel switches are facing renewed global scrutiny after last month’s deadly Air India crash that killed 260 people. A preliminary report revealed the aircraft’s fuel cutoff switches flipped mid-flight.