Last year, the F.A.A. said it was also investigating claims by a Boeing engineer that parts of the fuselage, or body, of the Dreamliner were improperly fastened together, which the whistle-blower said could cause premature damage to the plane over years of use.

It’s also the latest disaster to hit the beleaguered American aerospace giant — which has been dogged by a door that blew off a 737 jet, a leaky spacecraft that stranded astronauts on the International Space Station for months, as well as politically damaging delays in outfitting the new Air Force One jets.