A federal Aviation Administration official said Wednesday that the agency has 16 pending enforcement cases against Boeing, half of which have been opened since a door plug blew off a 737 Max in midflight.
The increase in cases was disclosed Wednesday during a National Transportation Safety Board hearing into the accident, which happened during an Alaska Airlines flight on Jan. 5.
Brian Knaup, who helps manage the FAA's oversight of Boeing, said one of the open cases involves the removal of parts that have already been installed on airplanes in production.
That is apparently what caused the mistake that led to the Alaska Airlines accident: Bolts that were removed to open the door plug for maintenance workers were not replaced when the panel was closed and the plane left a Boeing factory near Seattle.
Knaup's comment came near the end of a two-day hearing that included discussion of Boeing's poor tracking of parts-removal jobs. The company failed to document who opened the door plug, and the missing bolts were never found.
Another FAA official overseeing Boeing, Bryan Kilgroe, said he is kept awake at night wondering ''especially considering all that has happened since Jan. 5, is why is it so difficult to sustain a corrective action for the long term?''
Boeing said it had no comment.
The safety board released released testimony by Boeing employees who said they were pressured to build planes too quickly and not raise safety concerns.