Boeing 737 Max Door Plug That Flew Off Alaska Air Flight Missing 4 Key Bolts: Preliminary NTSB Report

Preliminary findings from an independent investigation show that a handful of key bolts appear to be missing from the door plug that blew out of a Boeing Co BA 737 Max 9 plane midflight in early January.

What To Know: New photos released Tuesday appear to show four key bolts were missing from the door panel that flew off during an Alaska Air Group Inc ALK flight Jan. 5, according to Reuters, citing a preliminary report from the U.S. National Transportation Safety Board (NTSB).

The door panel that blew out midair on Alaska Air flight 1282 prompted the Federal Aviation Administration to ground 171 Boeing Max 9s for most of the month before they were cleared to return to service in late January.

The NTSB had not made a determination as to what caused the mid exit door plug to fly off until it released its preliminary findings about the missing bolts Tuesday. The door plug is held in place by four bolts and then secured with “stop fittings” at 12 points along the panel.

“The investigation continues to determine what manufacturing documents were used to authorize the opening and closing of the plug during the rivet rework,” the report states.

The NTSB appears to be placing the blame on Boeing. CEO Dave Calhoun has said the company is responsible for what went wrong and has stressed that the company is owning its mistakes.

“While we report our financial results today, our full focus is on taking comprehensive actions to strengthen quality at Boeing,” Calhoun said in Boeing’s earnings report last week before acknowledging on the conference call that Boeing “caused the problem.”

The FAA is also auditing Boeing’s production process and looking into fuselage production at supplier Spirit Aerosystems Holdings Inc SPR. The agency has stopped Boeing from expanding production of its 737 MAX planes while it investigates the quality issues.

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Photo: courtesy of National Transportation Safety Board.