United Airlines announced Monday that a loose bolt was found in a panel on one of its Boeing 737 Max 9 planes. The bolt resembles the part of the Alaska Airlines jet that exploded during Friday’s flight, raising safety concerns about the Max 9 plane.
The revelations followed reports that Alaska Airlines had been warned three times about cabin pressure issues on the plane. These warnings were serious enough that the airline decided that the plane could no longer be used on flights to Hawaii.
United Airlines discovered loose bolts in the panel, known in the industry as a plug, after it began removing seats and sidewall liners to inspect the parts this weekend, the airline announced Monday. The plug is located where the exit door would have been if the jet had more seats.
A door plug suddenly flew off an Alaska Airlines jet as cabin pressure dropped about 10 minutes after takeoff from Portland, Oregon, on Friday, exposing passengers to howling winds and forcing pilots to rush back to the airport. forced to return. Door plugs, phones, toys, and other personal items all flowed out of holes in the side of the plane and landed all over the city.
The airline has canceled hundreds of flights as it prepares to inspect about 200 planes, which will be grounded until regulators and company officials say it is safe. Alaska Airlines uses 65 Max9 planes, or about 20% of its fleet, and United Airlines uses 79 planes, or about 8% of its fleet, more than any other airline, according to aviation data provider Cirium. did. Some passengers’ travel plans may be disrupted for several days.
The Federal Aviation Administration sent airlines instructions on Monday on how to conduct the tests, but Alaska Airlines and United Airlines said they were awaiting further approval from the FAA to begin.
Authorities, led by the National Transportation Safety Board, are focusing on plug installation and inspection, among other things.
“Investigators will likely focus on the manufacturing process of this particular aircraft,” said Jeff Gazzetti, a former NTSB and FAA investigator. “How was this door plug installed? Have you installed it?”
The door was originally installed by Spirit AeroSystems, which manufactures the bodies of the 737 Max and other aircraft. Investigators said they were looking to see if any construction had been carried out on or near the plane’s doors since it entered service in November.
NTSB Chairman Jennifer Homendy said investigators have a lot of work to do, including examining a plug recovered from a backyard near Portland. The committee will also examine the plug, which remained intact on the other side of the plane, interview the crew and passengers, review maintenance and repair records, and conduct laboratory analysis of the plane’s parts.
Investigators may also look into whether contractor AAR’s installation of wireless internet equipment on the aircraft between November 27 and December 7 played any role in the pressurization problems that were discovered after the work was completed. be. AAR said in a statement Monday that it “does not perform any work on or near the mid-cabin exit door plug of any particular aircraft.”
No serious injuries were reported, but experts said the accident could have been even more catastrophic, especially if the plane had been at a higher altitude. Homendy said Sunday night that the passengers included three infants and four unaccompanied children between the ages of 5 and 17.
Homendy said in a brief interview Monday that his team was reviewing the plane’s flight data recorder to determine whether the pressurization warning light could be linked to the door plug. The plane has several backup systems in case one of the pressurization systems fails.
“There could have been something wrong with the lights or some other unit, but the system has redundancy,” Homendy said.
Kathleen Bangs, an aviation expert and former airline pilot, said she believes the condition of the plane will lead to an investigation revealing a faulty door plug. Explosive decompression accidents typically occur in older planes where the metal has corroded or fatigued, Bangs said. In this case, the plane was nearly new, indicating there was likely a problem with the door plug, she said.
Anthony Brickhouse, a professor of aerospace safety at Embry-Riddle Aeronautical University, said the explosion could have been catastrophic had it occurred at a cruising altitude of more than 30,000 feet. “We could have envisioned a situation where more structure would come off and passengers who weren’t properly secured would be blown away. The forces would have been very high,” he said. .
Brickhouse, who previously investigated aviation accidents for the safety board, said most commercial aircraft begin to experience the effects of pressurization around 8,000 feet. Failure to properly control the air flowing into and out of the cabin can result in altitude sickness and hypoxia for passengers and crew.
According to the FAA, hypoxia is a condition that occurs when the brain is starved of oxygen, and when an airplane begins flight at an altitude of more than 10,000 feet or undergoes rapid depressurization, it is not properly pressurized. This can occur if there is no such thing. That’s why flight attendants instruct passengers to use drop-down masks in the event of a rapid decompression, Brickhouse said.
The FAA said in a statement that required inspections will focus on plugs, door components and fasteners.
“Our team has undergone a thorough FAA review and is fully prepared for the necessary inspections,” said Boeing Commercial Airplanes CEO Stan Diehl and Chief Aerospace Safety Officer Mike Delaney. “We have worked diligently to provide comprehensive technical instructions to operators.” he said in a message to department employees on Monday.
Other airlines operating up to nine aircraft are also located outside the United States, including Panama’s Copa Airlines, Turkish Airlines, and Icelandair.European Union Aviation Safety Agency announced On Monday, it was announced that Max 9 planes operating in Europe were not grounded because they have a different configuration.
The FAA previously said each aircraft inspection would take four to eight hours. Inspections of the roughly 200 Max 9 planes in the United States could take several days, aviation officials said.
Aviation regulators and Boeing said the tests were specific to the Max 9 jet and would not be conducted on other versions of the Max jet. The Max 9, along with the more popular Max 8, was discontinued for almost two years after two Max 8 crashes in 2018 and 2019 killed 346 people. .
Federal authorities investigating the incident are also looking into what caused the pressurization warnings to be issued for the damaged plane during three recent flights. Alaska Airlines employees reset the system and the plane returned to service, but the airline was restricting its use on flights to destinations such as Hawaii, Homendy said. He added that it was not yet clear whether the warning was related to Friday’s accident.
Alaska Airlines said in a statement that it cannot answer many unanswered questions about the plane or what led to the explosion without approval from the safety board. The company has asked the NTSB to share more information and said it would do so if allowed. Such investigations typically limit what the parties can share publicly.
Boeing CEO Dave Calhoun was scheduled to host a company-wide safety meeting on Tuesday to discuss the company’s response to the incident and reaffirm its commitment to safety. Boeing is still working to secure approval for the smaller Max 7 and larger Max 10.
Boeing stock fell about 8% on Monday, and Spirit AeroSystems stock fell 11%.
J. Edward Moreno Contributed to the report.