On Tuesday, the National Transportation Safety Board (NTSB) released findings from its investigation on the Boeing 737 Max 9 jet incident, during which a cabin panel blew off mid-flight. In their 19-page report, which included photographic evidence, the NTSB says that four bolts which were supposed to hold the door plug in place were not recovered.
“...the four bolts that prevent upward movement of the [mid exit door] plug were missing,” they wrote.
The door plug was first installed by the contractor Spirit AeroSystems in the US state of Kansas before being shipped to Boeing’s factory in the US state of Washington.
According to the board, the four bolts were removed last year when workers from Spirit AeroSystems repaired damaged rivets they discovered while at Boeing’s factory in Washington. A photo that was taken during the repairs shows at least three bolts had not been put back.
However, the report does not specify who is at fault for failing to reinstall the bolts. But Boeing’s CEO expressed that the company was “accountable” for the recent door plug incident.
"Whatever final conclusions are reached, Boeing is accountable for what happened," Dave Calhoun, the CEO of Boeing, said in a statement. "An event like this must not happen on an airplane that leaves our factory. We simply must do better for our customers and their passengers."
The NTSB investigation will continue and could take a year or more for the release of a final report.
In early January, an Alaska Airlines flight was soaring at about 16,000 feet after taking off from the US state of Oregon when one of its door plugs blew out, leaving a gaping hole in the side of the plane. The flight was carrying 177 people at the time.
Boeing’s Max 9 planes were grounded for several weeks afterwards. They have since been allowed to return to service after being inspected, but the Federal Aviation Administration (FAA) has said it will not allow for any further production of the Max program.