Boeing 737 in Alaska Air accident was missing bolts, US says

A dramatic accident on an Alaska Airlines flight last month was apparently triggered by a door plug that hadn’t been properly attached before the plane was delivered by Boeing Co., US investigators said Tuesday.

Evidence including a photo of the door at Boeing’s Renton, Washington, factory suggest that four bolts that acted as a fail-safe mechanism to hold the panel in place were missing, according to a preliminary 19-page report from the National Transportation Safety Board. The door had been worked on during final assembly but NTSB is still reviewing what was done and why.

The incident has become the biggest crisis for Boeing since its entire fleet of Max jets was grounded worldwide in 2019 following two fatal crashes. Max 9 jets with the same door configuration as the Alaska jet were grounded for weeks until they could be inspected, and regulators are poring over Boeing’s manufacturing processes and ratcheting up pressure on the company’s management.

The report reaches no conclusions about what caused the Jan. 5 failure, but it’s an unusually detailed account of the safety board’s initial fact-gathering. The safety board can take a year or longer to reach a formal conclusion.

Boeing said it will review the findings and continue to cooperate with US investigators.

“Whatever final conclusions are reached, Boeing is accountable for what happened,” Boeing Chief Executive Officer Dave Calhoun said in a statement. “We are implementing a comprehensive plan to strengthen quality and the confidence of our stakeholders.”

Spirit AeroSystems Holdings Inc., Boeing’s most important supplier and the company that builds the 737 fuselages, has also been under scrutiny in the wake of the accident. Boeing shares were up 0.9% as of 3:49 p.m. in New York. Spirit shares were up 4.1%.

The NTSB report shows that the day after arriving at Boeing’s Renton facility on Aug. 31, the 737 Max 9 airframe was flagged for having five damaged rivets along the side of the door plug where the failure later occurred. To replace those rivets, mechanics had to remove the door plug and four retaining bolts that hold it in place.

The rivets were replaced, according to a report by Spirit Aero personnel on Sept. 19. Afterward, a photo obtained by NTSB investigators showed the door plug missing retention bolts in at least three places. The photo was shared by Boeing employees before work on the plane’s interior, the report said.

In addition, the holes where the retention bolts would have been installed showed “no evidence of heavy contact damage,” the report said. That suggests the bolts weren’t present when the panel blew open on the Alaska Air Group Inc. jet shortly after takeoff from Portland last month. The plane violently lost pressure and was forced to make an emergency landing. Seven passengers and a flight attendant reported minor injuries.

The initial information in the report renews the focus on Boeing’s manufacturing processes and the company’s quality checks. The Federal Aviation Administration is conducting enhanced oversight of Boeing and Spirit. FAA Administrator Michael Whitaker on Tuesday told House lawmakers that the agency’s reviews are still underway, but so far it hadn’t found anything that would require “immediate action.”

Issues with Boeing’s work on the Max family of aircraft continue to emerge. On Feb. 4, the company disclosed that it had discovered manufacturing flaws with rivet holes in about 50 undelivered 737s. The problem originated with Spirit, a spokesman for that company said. 

The problem disclosed Feb. 4 is the latest in a series of glitches originating with Boeing’s former aerostructures unit. A drilling mishap on an aft pressure bulkhead supplied by Spirit Aero slowed deliveries of the 737 Max last year, the planemaker’s most important generator of cash flow. A separate issue with tail-fin fittings affected output earlier in 2023. 

Boeing will also have to contend with the possibility of labor disruption later this year. Boeing’s largest union, the International Association of Machinists and Aerospace Workers, will demand a 40% pay raise over three or four years, emboldened by a resurgent US labor movement, a scarcity of qualified aerospace workers and pressure on Boeing to stabilize work in its factories. 

The FAA is about halfway through its review and expects to release findings and possible recommendations as soon as this month, Jodi Baker, FAA deputy associate administrator for aviation safety, said Monday.

Senator Maria Cantwell, the Washington Democrat who chairs the Commerce Committee, said she would hold hearings on the issues raised by NTSB. The report “shows how much we need to focus on quality assurance,” she said in an interview.