Boeing Subcontractor Scrutinized Over Door Plug Failure

Employees of Spirit AeroSystems allege poor quality control in legal filing.

The door plug on an Alaska Airlines Boeing 737 Max 9 blew off as the aircraft climbed through 16,000 feet. [Courtesy: NTSB]

Litigation filed against a Boeing subcontractor is the latest wrinkle in the investigation of the Boeing 737-9 Max 9 that lost a door plug in mid-flight, resulting in cabin depressurization and an emergency landing. Spirit AeroSystems is facing a class action lawsuit filed in federal court in December by former employees who allege the Wichita, Kansas-based manufacturer didn’t listen when they raised concerns about product quality.

According to the investigative publication The Lever, the complaint was filed on December 19 in federal court in New York state on behalf of investors in Spirit AeroSystems. The complaint alleges that employees of the aerostructure manufacturer repeatedly warned corporate officials about "sustained quality failures" and "excessive amounts of defects," but their concerns were ignored.

Employees allegedly discussed that it was only a matter of time before one of these substandard parts made it onto a jet delivered to a customer. Among the parts made by Spirit AeroSystems is the door plug that is used to turn a space for an optional emergency exit into a window. From the interior of the cabin it looks like the other windows. From the exterior the outline of the door is clearly seen on the fuselage.

On January 5 the left door plug of Alaska Airlines Flight 1282 blew off the aircraft as it climbed through 16,000 feet, resulting in violent decompression. The airplane had just taken off from Runway 28L at Portland International Airport (KPDX) in Oregon. The flight crew declared an emergency and the aircraft returned to the airport. There were no serious injuries among the 177 on board.

The door plug was located adjacent to seats 26A and 26B. Both were heavily damaged, and parts of them expelled from the aircraft along with personal items such as cellphones. According to the New York Post,  a 15-year-old boy identified was seated in 25A, the window seat in the row directly ahead of the door plug when it blew—the force sucking the shirt off his back. When the wind died down, he relocated to a seat away from the gaping hole in the airplane and, like others on board, put on a supplemental oxygen mask. As it was impossible to talk over the noise, the woman sitting next to the boy used a cellphone as a tablet, and they communicated by text. He said he was OK but had some scrapes. They posed for a selfie at the end of the ordeal.

Since the event, the FAA has grounded all 150 Boeing 737 Max 9 aircraft and instructed operators to inspect them. Both Alaska Airlines and United Airlines utilize the 737 Max 9 and have reported finding loose bolts.

The National Transportation Safety Board (NTSB) recovered the door plug on Monday along with other bits and pieces torn from the aircraft. They are being shipped to the NTSB laboratory in Washington, D.C., where they will be put under a microscope for examination.

According to Clint Crookshanks, an aerospace engineer with the NTSB who is part of the structures team on this investigation, explained that the door plug is held in place by 12 stop pads that interface with 12 pins to prevent it from blowing out of the fuselage. The door is installed using guide tracks and roller guides then secured with four bolts. Crookshanks noted the guide tracks were fractured, but as of yet, the NTSB has not determined if the bolts gave way or if they were even installed.

The investigation has revealed the aircraft was delivered to Alaska Airlines in October 2023, and according to flight trackers, had logged approximately 145 flights at the time of the accident.

The NTSB has verified there were three maintenance write-ups made by the crews for air pressurization warning lights. This is a triple redundant system, with a primary and secondary that control cabin pressure by computer and a third system controlled manually. Maintenance issues were reported on December 7, January 3, and January 4.

The FAA allows aircraft to fly with these maintenance issues since it is considered a triple redundancy.

The NTSB said it will be investigating whether the warning lights were “correlated in any way to the expulsion of the door plug and the rapid decompression. The agency said  the probe into the blowout could take months.

Boeing said it is aiding the NTSB in the investigation. On Tuesday, company CEO and president Dave Calhoun held a safety meeting via webcast, addressing the employees and noting how the event shook him "to the bone" when he saw the image of the blowout.

"I didn't know what happened to whoever was supposed to be in that seat next to that hole,” Calhoun said. “I got kids. I got grandkids, and so do you. This stuff matters. Everything matters. Every detail matters. I know I am preaching to the choir here. It's not a lecture by any stretch. It is a reminder of the seriousness at which we have to approach our work."

Calhoun added that Boeing has been in touch with its customers, who are understandably anxious and have grounded their fleets as a precaution.

"They did it quickly to prevent another potential accident," he said. "We have to demonstrate with our actions that every Boeing airplane is safe in the sky. We are starting from a very anxious moment with our customers, and we have to deal with that reality."

Boeing said it wants to continue to play a key role in the NTSB investigation, providing it with information to help determine the cause of the accident.

"They are as good as it gets," Calhoun said of the agency. "I trust them every step of the way."

In the meantime, the FAA is working with operators to develop an inspection process. FLYING reached out to Spirit AeroSystems and were referred to a statement on the company website: "Spirit AeroSystems has been working closely with our customer since the event with Alaska Airlines Flight 1282 on [January] 5. A Spirit team is now supporting the NTSB’s investigation directly. As a company, we remain focused on the quality of each aircraft structure that leaves our facilities.”

Meg Godlewski has been an aviation journalist for more than 24 years and a CFI for more than 20 years. If she is not flying or teaching aviation, she is writing about it. Meg is a founding member of the Pilot Proficiency Center at EAA AirVenture and excels at the application of simulation technology to flatten the learning curve. Follow Meg on Twitter @2Lewski.

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