A month after the loss of the door of an Alaska Airlines 737 MAX 9 in mid-flight, the National Transportation Safety Board (NTSB) published a preliminary investigation report on Tuesday, February 6 .
According to the NTSB, the lack of wear or deformation around some of the holes “indicates that four bolts intended to prevent the cap holder from moving upward were missing before it moved.” The agency collected written documents and photos that show Boeing employees removed four bolts at these locations during an inspection at the Renton, Washington, plant before delivery of the plane, in October.
The operation was carried out to replace five damaged rivets in the cabin of the aircraft. Other photos taken after changing the rivets show that, in at least three points, the bolts had not been reinstalled. This door was used to block an exit and it was not intended for it to be opened, this model having sufficient emergency exits in this configuration.
On January 5, she took off on Alaska Airlines’ MAX 9 from Portland, Oregon to Ontario, California. The incident caused only a few minor injuries. Before the NTSB report was released, Alaska Airlines had already reported “loose equipment” after preliminary inspections.
Owner of the largest fleet of 737 MAX 9s (79 aircraft), United Airlines said it had discovered, during checks, “bolts that needed to be tightened”.
In recent months, Boeing has experienced other episodes of failure and had to slow down its deliveries due to problems on the fuselage, in particular on the rear bulkhead of the aircraft.
Boeing under FAA surveillance
Tuesday, during a hearing in Congress, the head of the American Civil Aviation Regulatory Agency (Federal Aviation Administration, FAA), Mike Whitaker, who took office in October, considered it necessary to strengthen supervision of Boeing after the 737 MAX 9 incident. “There have been problems [with Boeing] in the past and it appears that they have not been resolved,” said the new FAA administrator during a hearing before the House Subcommittee on Aviation. “So we feel like we need to raise the level of supervision to deal with this,” he continued.
The FAA had dispatched around twenty inspectors to Boeing, currently hard at work to check the assembly conditions of the group’s aircraft. The regulator also sent around ten of its controllers to the aircraft manufacturer’s main subcontractor, Spirit AeroSystems.
This approach, Mr. Whitaker said, breaks with the methods traditionally used by the agency, which were essentially based on the study of documents transmitted by Boeing. The FAA has commissioned a six-week audit from a specialized firm, which is currently being carried out, the conclusions of which will be used to define a new sustainable supervision method. “We haven’t made a decision yet, but I expect we will keep people on site,” the FAA boss said.