Alaska Airlines said its technicians have found loose hardware on some of the airline’s Boeing 737 Max 9 aircraft, as federal investigators intensify scrutiny of the bolts meant to hold in a piece of the plane that blew out during a midair flight last week.
The discovery was made as technicians began preparing sections of the aircraft for inspections ordered by the Federal Aviation Administration. United Airlines also said Monday that preliminary inspections of grounded Boeing 737 Max 9 planes have turned up loose bolts and other issues with the part of the aircraft that failed on the Alaska Airlines flight over Portland, Ore.
National Transportation Safety Board officials said at a news conference Monday evening that guide tracks on the Alaska Airlines door plug were fractured and that the agency is investigating the absence of four bolts designed to keep the plug from moving upward in a motion that would normally help disengage it for maintenance and repairs.
It is unclear whether the four bolts were absent at the start of the flight Friday, or if they went missing after the accident, NTSB chair Jennifer Homendy said. The door plug on the right side of the plane, which remained intact, had no discrepancies or missing parts, she added.
On Monday evening, Homendy said there were “no indications whatsoever” that three previous activations of the auto-pressurization fail light on the Alaska Airlines aircraft were linked to the door plug accident.
The light, designed to signal failures in the control of cabin pressure, had illuminated on three flights in the weeks leading up to the accident, prompting tests and a reset by maintenance. A later request from Alaska Airlines for a deeper look had gone unfulfilled before the accident, she said.
Boeing said in a statement Monday: “As operators conduct the required inspections, we are staying in close contact with them and will help address any and all findings.”
The company added: “We are committed to ensuring every Boeing airplane meets design specifications and the highest safety and quality standards. We regret the impact this has had on our customers and their passengers.”
The situation will no doubt compound the woes at Boeing, which has struggled to rebuild its reputation since an earlier model of the Max was grounded after two crashes killed 346 people several years ago. Investigations at the time revealed problems with the design of an automated system on that plane, flaws that had not been fully disclosed to the FAA.
One hundred seventy-one Boeing 737 Max 9 planes have been grounded amid the investigation into the accident on Friday, which caused rapid depressurization in an Alaska Airlines plane and triggered an emergency landing.
There were no serious injuries in the accident, but the dramatic midair blowout caused the FAA to order inspections of the jetliners. The FAA previously said the inspections could take four to eight hours per plane, but on Monday it said that was no longer accurate, without offering a revised estimate.
As part of their investigation, federal authorities are gathering evidence that dropped across the Portland area during the accident, including the door-like plug, which landed in a schoolteacher’s backyard and will be sent to a lab in Washington, D.C., for further examination.