The report provided the first official insights into the sequence of events leading to the shocking incident. The findings of investigators and the airlines are ratcheting up pressure on Boeing to address concerns that have grown since the terrifying fuselage blowout on January 5. A plug covering a spot left for an emergency door tore off the plane as it flew 16,000 feet above Oregon.
“Whatever final conclusions are reached, Boeing is accountable for what happened. An event like this must not happen on an airplane that leaves our factory,” Boeing CEO Dave Calhoun said in a statement.
“We simply must do better for our customers and their passengers,” he added.
The NTSB report, released on Tuesday, focused on how the panel, installed as a optional exit in the MAX 9 model, could have separated from the aircraft. It highlighted that the panel is initially fastened by four bolts and then secured by “stop fittings” positioned at 12 different locations along the plug and door frame.
“The failure to re-install bolts on a safety-critical component of this 737 MAX 9 aircraft is a serious error that signals larger quality control lapses that must be corrected,” representative Rick Larsen, the top Democrat on the committee overseeing the FAA, said.
The plug, which was manufactured by Spirit AeroSystems, a former subsidiary of Boeing, was produced at Spirit’s facilities in Malaysia and then delivered to its Wichita, Kansas, facility in May 2023. It reached Boeing’s assembly plant in Renton, Washington, on August 31.
The report indicates that the panel had to undergo removal at Boeing’s factory before being reinstalled. Initial findings also included photo evidence suggesting that the bolts required to secure the plug were missing.
According to the report, the panel was initially removed to address rivet damage reported by Boeing workers on September 1, a day after it arrived in Renton. Investigators are still working to determine the documentation used to authorize the opening and closing of the plug during the rivet repair.
A photo in the report shows three visible locations where bolts are missing, with the fourth location covered by insulation.
“Photo documentation obtained from Boeing shows evidence of the left-hand MED plug closed with no retention hardware (bolts) in the three visible locations,” the report said. MED is short for “mid exit door.”
Boeing, which has had problems with various planes over the years, pledged to “help address any and all findings” that airlines make during their inspections of Max 9 jets.
The company has delivered more than 200 to customers around the world, but 171 of them were grounded by the Federal Aviation Administration until the door plugs can be inspected and, if necessary, fixed. The door plugs are inserted where emergency exit doors would be located on Max 9s with more than about 200 seats.