Boeing factory workers felt pressured to prioritize production speed over quality and said they did not receive enough training to properly perform their jobs, according to the results of a special investigation by the Federal Aviation Administration (FAA) published Wednesday.

Boeing must do more to improve the aircraft safety following a door plug blowout in January and other mishaps, Federal Aviation Administration Administrator Mike Whitaker told a House committee Tuesday.

Boeing Co. will need three to five years to rebuild its safety culture that regulators have found to be rife with shortcomings, the top US aviation safety official said.