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.

Investors and the wider public are looking for answers after Thursday’s crash of an Air India 787 jet. Both of the plane’s black boxes have been recovered.

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.