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.

The crash is Dreamliner's first fatal crash as the plane had a stellar safety record, delivering 1,000 planes safely in 14 years.