The two engines on the Air India flight shut down within one second of each other before the Boeing 787 Dreamliner crashed last month in Ahmedabad, India, killing at least 260 people, according to a preliminary report released Friday.

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 FAA’s Continued Airworthiness Notification, dated July 11, was issued days after India’s Aircraft Accident Investigation Bureau (AAIB) released its initial findings into last month’s fatal Air India 787-8 crash, which killed all 260 people on board. The report questioned how the aircraft’s engine fuel cutoff switches flipped during takeoff.