Boeing to change design to prevent future 737 MAX 9 door panel blowouts

Boeing has said it plans to make design changes to prevent a future midair cabin panel blowout like the one in an Alaska Airlines 737 MAX 9 flight in January which spun the plane-maker into its second major crisis in recent years.

Boeing’s senior vice president for quality, Elizabeth Lund, said on Tuesday the plane-maker is working on design changes that it hopes to implement within the year and then retrofit across the fleet.

Investigators have said the plug in the new Alaska MAX 9 was missing four key bolts.

“They are working on some design changes that will allow the door plug to not be closed if there’s any issue until it’s firmly secured,” Lund said during the first of a two-day National Transportation Safety Board (NTSB) investigative hearing in Washington, DC.

Lund’s comments followed questioning on why Boeing did not use a type of warning system for door plugs that the plane-maker includes on regular doors which sends an alert if it is not fully secure.

The Alaska Airlines incident badly damaged Boeing’s reputation and led to the MAX 9 being grounded for two weeks, a ban by the United States Federal Aviation Administration (FAA) on expanding production, a criminal investigation and the departure of several key executives. Boeing has promised to make significant quality improvements.

The NTSB also released 3,800 pages of factual reports and interviews from the ongoing investigation.

Boeing has said no paperwork exists to document the removal of four key missing bolts. Lund said Boeing has now put a bright blue and yellow sign on the door plug when it arrives at the factory, which says in big letters, “Do not open” and adds a redundancy “to ensure that the plug is not inadvertently opened”. It also has new required procedures if the door plug needs to be opened during production.

A flight attendant described the moment of terror when the door plug blew out. “And then, just all of a sudden, there was just a really loud bang and lots of whooshing air, like the door burst open,” the flight attendant said. “Masks came down, I saw the galley curtain get sucked towards the cabin.”