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Missing bolts from Boeing 737 door reinforce importance of repair procedures

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Collision Repair | Repair Operations
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An exit door that was ripped off a Boeing airplane in-flight last month makes the case for following OEM repair and inspection procedures as a crucial contributor to safety and proper functionality.

On Jan. 5, Alaska Airlines flight 1282, a Boeing 737-9, returned to Portland International Airport after its left mid-exit door (MED) plug was torn from the plane, leading to rapid cabin decompression. A MED plug seals up unused emergency exits and is only visible outside of the plane. It’s only intended to be opened for maintenance and inspection.

Of the 171 passengers and six crew members, seven passengers and one flight attendant reported minor injuries.

The shirt of one of the passengers, a 15-year-old boy, was sucked off by suction after the door was pulled upward, out, and toward the tail of the plane, according to a CBS News report.


A teen on the Alaska Airlines flight had his shirt ripped off when the door plug blew. A stranger tried to help calm him down.

♬ original sound – cbsnews

“The separation of the MED plug from the airplane adversely affected the pressurization performance of the airplane and the damage to the MED plug adversely affected its structural strength,” a preliminary report from the National Transportation Safety Board (NTSB) states.

“The captain said that, while climbing through about 16,000 ft, there was a loud bang. The flight crew said their ears popped, and the captain said his head was pushed into the heads-up display (HUD) and his headset was pushed up, nearly falling off his head. The FO [first officer] said her headset was completely removed due to the rapid outflow of air from the flight deck. Both flight crew said they immediately donned their oxygen masks. They added that the flight deck door was blown open and that it was very noisy and difficult to communicate.”

The MED plug was manufactured by Spirit AeroSystems Malaysia on March 24, 2023, and was received at Spirit AeroSystems Wichita on May 10. Boeing received the fuselage on Aug. 31, and on Sept. 1 damage to five rivets on the edge frame forward of the left MED plug was documented, according to the NTSB report.

“Documents and photos show that to perform the replacement of the damaged rivets, access to the rivets required opening the left MED plug,” the report states. “To open the MED plug, the two vertical movement arrestor bolts and two upper guide track bolts had to be removed.”

It adds that the rivets were replaced following engineering requirements by Spirit AeroSystems personnel and the work was completed on Sept. 19. NTSB determined four bolts were missing from damage patterns, missing contact damage or deformation of the bolt holes, Boeing post-repair photos, and destructive testing of the recovered MED plug. The plug was found in the backyard of a residence.

The airplane was delivered to Alaska Airlines on Oct. 31, 2023 and put into service on Nov. 11, according to the NTSB report. At the time of the accident, the airplane had accumulated 510 total hours and 154 cycles.

Damage patterns and missing contact damage or deformation of the bolt holes were signs the NTSB found as evidence that four bolts meant to prevent upward movement of the MED plug were missing before the plug was torn off the plane.

“Damage to the passenger cabin included: damage in seat rows 25ABC and 26ABC,” the report states. “…deformation of the doorframe of the forward lavatory, and buckling and displacement of the sidewall panels and trim throughout the airplane. There were no indications of any other failures or malfunction of the airplane or any of its systems.”

Boeing has since issued multiple multi-operator messages (MOMs), the most recent, dated Jan. 25, including revised instructions for inspecting 737-9 airplanes with MED plugs, according to the NTSB report.

NTSB’s investigation is ongoing.

The incident should serve as a startling reminder that repair scenarios, and attention and adherence to engineering specified details during them, can mean the difference between life and death in a future collision, even down to something as seemingly small as a bolt.

Repairers should always check OEM repair procedures before and during every repair, follow the procedures to a T, conduct pre- and post-scans of advanced driver assistance systems (ADAS), and conduct pre- and post-repair safety inspections, such as seatbelts and child safety seat anchors.

However, “Who Pays for What?” surveys of collision repairers often find that they’re not asking to be paid for safety testing.

For example, one of the 2023 surveys found that 37% of collision repairers hadn’t sought reimbursement from insurers for test welds, leading to questions about whether the procedure is even being performed at the majority of repair centers.

“We need to wake up on this one,” wrote Collision Advice CEO Mike Anderson, in the survey results. “This is a non-negotiable procedure that every OEM says is necessary. If your techs aren’t doing this, don’t delay, get them doing it today. I recently was at a shop that set up and performed a destructive test weld that failed because the welding equipment did not have the latest software update. That was not the first time I’ve seen that happen. Be sure to check with your welder equipment company to know when any updates should be performed.

“Our whole industry needs to acknowledge how critically important test welds are. Repairers need to perform them routinely, and insurers need to pay for them routinely.”

It can also become an issue in court. A lawsuit settled last year blamed an improperly installed steering rack as the cause of a collision that injured a 27-year-old man. The driver said the steering rack had been installed at an auto repair facility about three months before he “lost all steering suddenly and unexpectedly,” while driving, causing the collision.

It’s not clear what kind of vehicle the driver was operating, but some automakers have specific repair instructions on replacing a steering box; an operation that has been contested by insurance companies in the past, not always in agreement with OEM directives. BMW, as an example, demands a steering box replacement for any one of numerous conditions, including during an unacceptable torque increase and jamming when the steering box is turned from lock to lock without hydraulic/electrical assistance.

At a 2022 Collision Industry Conference (CIC) meeting, Database Enhancement Gateway (DEG) Administrator Danny Gredinberg gave a presentation on the importance of researching OEM repair procedures. As an example of what can happen when research isn’t done, he bent a piece of steel he purposely heat-treated — an improper procedure.

After bending the steel with his hand, he demonstrated doing so can create a crack. Doing that with a more delicate metal, like aluminum, could cause damage that when “taking the time to understand what you’re working on” would be avoided, Gredinberg said.

Bruce Halcro, chairman of the Society of Collision Repair Specialists (SCRS) at the time, and Ron Reichen, a former SCRS chairman, shared at a 2019 meeting that OEM procedures aren’t one-size-fits-all.

Reichen said each automaker has a different process for their procedures. For example, in the case of a 2019 Ascent Limited alone, “the marching orders are different” depending on whether an air bag has deployed, he said.

Halcro said the type of impact also could command different requirements.

He added that insurers sometimes are confused by the need for an inspection, arguing that they already paid for a diagnostic scan, but Reichen noted that a scan won’t address certain factors detectable by a physical inspection.

Halcro described checking items like cage nuts for stress points and stranded wiring for stretching that could cause connection or conductivity issues.

The Boeing door plug incident also shows the importance of compiling repair documentation with photos of every repair. Doing so can help protect repairers and shops from liability for future collisions if repairs are ever called into question, and prove repair procedures were carried out correctly.

During a CIECA webinar held last July, DCR Systems President and CEO Michael Giarrizzo Jr. said to achieve transparency in how and what repairs take place, the industry needs to move away from using estimates as documentation.

“It really doesn’t apply anymore,” he said. “That estimate does nothing but mislead everyone inside the process. It really has no place anymore with complete disclosure and documentation of what needs to be done and what was actually done.”

Instead, repair plans should hold all documentation and be kept with each vehicle for the life of it so that every owner and repair shop knows what’s been done to it in the past, he said.

Also, Giarrizzo added that pre-scans and inspections are paramount before collision repairs because any prior damage or substandard repairs that are causing issues need to be addressed first. It also prevents customers from thinking your shop caused the damage or completed the improper repairs.

Keep documentation in mind for sublet repairs as well because the primary shop is also liable for that work.


Featured image: Stock image of a MED plug on an airplane. (Credit: Vajirawich Wongpuvarak/iStock)

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