As the world waits for answers on the fatal Air India Boeing 787 crash, accident investigators have narrowed their focus on the engine fuel control switches.

A preliminary report on the fatal crash of an Air India Boeing 787 Dreamliner is expected by Friday, according to three sources familiar with the matter. The investigation is now centred on the movement of the aircraft’s engine fuel control switches.

The Times of India reported Tuesday that a preliminary report had been submitted to officials. Details of the report weren’t available.