An investigation into the June crash so far hasn’t pointed to a problem with the Boeing 787 Dreamliner or its GE Aerospace engines.

A month after the worst aviation accident in India in decades, authorities are poised to release a preliminary report into the catastrophe, offering the first official clues to what caused the aircraft to plummet back to the ground just 30 seconds after taking off.

As the world waits for answers on the fatal Air India crash, accident investigators have narrowed their focus on the engine fuel control switches.