In response to reports of unspecified issues with bolts in door plugs on Boeing 737-900ER jets, the U.S. Federal Aviation Administration (FAA) has issued a recommendation for airlines to inspect and ensure the proper securing of these door plugs. This advisory comes on the heels of the FAA’s decision to ground 171 Boeing 737 MAX 9 planes following a mid-air cabin blowout of a door plug on an Alaska Airlines MAX 9 jet on January 5.
The Safety Alert
While the 737-900ER is not part of the newer MAX fleet, it shares the same optional door plug design, allowing for the addition of an extra emergency exit door when carriers choose to install more seats. Some airlines conducting additional inspections on the 737-900ER mid-exit door plugs have reported findings related to bolts during maintenance inspections.
The FAA has issued a “Safety Alert for Operators,” urging air carriers to perform crucial portions of a fuselage plug assembly maintenance procedure promptly, specifically addressing the four bolts used to secure the door plug to the airframe. Boeing, the manufacturer of the aircraft, expressed full support for the FAA’s action.
Alaska Airlines and United Airlines, the only two U.S. carriers operating the MAX 9, previously reported loose parts on multiple grounded MAX 9 aircraft during preliminary checks, leading to the cancellation of thousands of flights. The FAA has indicated that MAX 9 planes will remain grounded until deemed safe to return to service.
FAA issues alert on door plugs for 2nd Boeing plane | Boeing 737-900ER
Inspections Initiated
In contrast to the MAX 9 disruptions, Boeing 737-900ER aircraft, which have accumulated over 11 million hours of operation and 3.9 million flight cycles, have not experienced issues with the door plug, according to the FAA. Both United and Alaska have initiated inspections on their 737-900ER fleets, with United expecting completion in the next few days without customer disruption.
Delta Air Lines, another operator of the 900ER, has proactively undertaken inspections, expressing confidence that there will be no operational impacts. While the three U.S. carriers primarily operate the majority of 737-900ERs with door plugs globally, the FAA continues to review data from inspections of an initial group of 40 Boeing 737 MAX 9 jets as part of the process to eventually unground the model.
FAA Administrator Mike Whitaker stated that the agency is working to restore confidence in the integrity of these plug doors. The National Transportation Safety Board is also investigating the issue, examining records related to the door plug to determine if bolts were properly secured or installed on the Alaska Airlines jet that experienced the mid-air cabin blowout.
