Door That Blew Off Boeing 737 Max Was Likely Missing Several Bolts: NTSB

Photos taken during repair work on the plane in September show no evidence the bolts were replaced after removal, according to preliminary NTSB findings.

A door panel that blew off of an Alaska Airlines plane while it was flying over Oregon last month appears to have been missing four bolts, according to a preliminary report released Tuesday by the National Transportation Safety Board.

The bolts that secure the panel to the fuselage had been removed from the Boeing 737 Max 9 during repair work at Boeing’s factory in Renton, Washington, and apparently were not replaced, the report says.

Photos taken during the repair work in September show no evidence that the bolts were replaced before the panel, called a door plug, was closed by workers, the report states.

The report notes that a pressurization light in the plane came on during three flights following the repair work. The NTSB previously said that these alerts, on Dec. 7, Jan. 3 and Jan. 4, resulted in the aircraft being restricted from making long flights over water in case it needed to make an emergency landing.

The panel blew off the jetliner shortly after takeoff on Jan. 5, leaving a gaping hole in the side of the plane. There were 177 people on the aircraft, including passengers and crew members, but no major injuries were reported.