Four bolts intended to prevent the door plug of a Boeing 737 Max 9 from rising and then opening completely during flight are missing, and investigators are trying to determine what role, if any, they played in the terrifying episode in the air over Portland, Oregon. ., last week.
Minutes after Alaska Airlines Flight 1282 took off from Portland International Airport for Ontario on Friday, the plane’s left door plug, which fills an additional emergency exit that Alaska was not using on its modified 737 Max 9 design , exploded at 16,000 feet.
The National Transportation Safety Board is still investigating what caused the hole in the side of the plane to open, but during a news conference Monday night, officials said they had not yet found the four bolts meant to hold the door in place.
It’s unclear whether that means the screws were missing before the flight or if they somehow broke, NTSB Chairwoman Jennifer Homendy said.
The missing bolts are the same ones Alaska and United airlines reported Monday found loose on some of their 737 Max 9 planes during inspections after all planes were grounded following the incident.
“We have not yet recovered the four screws that restrict [the door] of their vertical motion, and we have not yet determined whether they existed there,” NTSB investigator Clint Crookshanks said at Monday night’s news conference.
The NTSB is in the process of transporting the door stopper, which was found by a Portland teacher in his backyard, to its laboratory in Washington, D.C., where investigators hope to determine whether the hardware was in place before the flight.
“We’ll be able to determine if the screws were there,” Homendy said.
The revelation comes after the Federal Aviation Administration on Saturday issued an emergency airworthiness directive to all airlines with 737 Max 9 planes in their fleet, grounding the planes “until the plane is inspected and tests have been carried out.” all applicable corrective actions.
Alaska and United reported finding “loose hardware” and bolts.
According to Flightradar24, an industry tracking company, five airlines worldwide have 189 of the 737 Max 9 planes that use mid-cabin exit door plugs, like the one on Flight 1282. United Airlines is the largest aircraft operator, with 79 aircraft. Alaska Airlines operates 65.
Copa Airlines, Aeroméxico and Turkish Airlines also have the plane in their fleets.
On Monday, Homendy said the NTSB was aware that other airlines had reported problems with the same bolts after inspecting their 737 Max 9 planes. Although the agency was “focused on this plane” and finding out what caused the bolt to open gate of Flight 1282, the agency wouldn’t rule out taking a broader look at Boeing planes.
“We need, first and foremost, to find out what happened to this plane,” he said. “If we have a major system-wide or fleet-wide issue, we will issue an urgent safety recommendation or push for a change.”
The NTSB has been gathering information and is working with the FAA, he said.
Investigators say they believe the door moved upward and came loose from 12 “stops” holding it in place, before swinging open.
According to Crookshanks, there are a dozen stop pads in the body of the plane that align with 12 pins on the door stopper when it is secured, preventing it from opening due to the pressure difference inside and outside the cabin. The four missing bolts prevent the door from being lifted from its secure position.
Investigators also discovered that the door plug guides, which match the fuselage guide rollers, were broken.
“Right now we’re focused on the evidence, and the evidence tells a story,” Homendy said. “The components of the door stopper tell a story. “We have to follow the evidence and see where it takes us before jumping to any kind of conclusion.”
On Tuesday, the FAA said all Boeing 737 Max 9s with a door plug would remain grounded until the agency determined they could safely return to service.
“We are in close contact with [federal inspectors] and will help address any and all findings,” Boeing said in a statement. “We are committed to ensuring that every Boeing aircraft meets design specifications and the highest safety and quality standards. “We regret the impact this has had on our customers and their passengers.”
The FAA was also waiting for Boeing to instruct operators to inspect and maintain door plugs, according to a statement from the FAA.
Boeing sent an initial set of instructions, but revised instructions were requested “due to feedback received” from operators, according to the FAA.
