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.

Air India faces fresh turbulence following last week's fatal crash as additional safety inspections on its Dreamliner fleet lead to flight delays, cancellations and growing passenger anxiety.

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.