Authorities in India have released the preliminary results of their investigation into the the Boeing 787-8 Dreamliner crash in June that killed 229 of the 230 passengers aboard and all 12 crew members.

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

Preliminary findings into last month’s Air India plane crash suggest the aircraft’s fuel control switches were turned off, causing a loss of engine thrust shortly after takeoff