The preliminary finding gives investigators a new line of inquiry as they study a crash that killed all but one of the plane’s passengers.

An Air India Boeing 787, the same kind of plane that crashed 4 days earlier, was forced to turn around after a midair "technical issue," the airline says.

Investigators in India are studying the black boxes of a Boeing 787 Dreamliner after recovering them from the aircraft wreckage to ascertain the cause of last week's plane crash that left at least 270 people dead.