The Federal Aviation Administration has recommended airlines inspect another model of Boeing airplanes, broadening the scope of scrutiny beyond the 737 MAX 9 model.
The FAA said Sunday evening it was recommending operators of Boeing’s 737-900ER aircraft “visually inspect mid-exit door plugs to ensure the door is properly secured.”
The 737-900ER is not part of the newer MAX fleet, but the planes have the same door plug design. That door plug is a panel that fills a space that some airlines use as an emergency exit.
On Jan. 5, on an Alaska Airlines flight operating a Boeing 737 MAX 9, the door plug on one side of the plane blew out at 16,000 feet in the air, causing the cabin to rapidly depressurize and leaving a gaping hole in the plane. The flight landed safely back at Portland International Airport, where some passengers reported non-life-threatening injuries.
The FAA grounded the MAX 9 planes that fill the space with a door plug shortly after. Those planes will remain grounded until airlines inspect each aircraft, following instructions from Boeing and the FAA.
On Wednesday, the FAA said airlines had completed the first 40 preliminary inspections of the 737 MAX 9 planes. The FAA is reviewing that data and will determine if it will sign off on inspection instructions for the rest of the MAX 9 fleet.
The FAA estimated the MAX 9 inspections would impact 171 planes and that each inspection would take four to eight hours per aircraft.
The National Transportation Safety Board, which is leading the investigation into what led the door plug to blow out, has indicated that four bolts that hold the door plug in place were either missing or misinstalled. The NTSB is examining the door plug, which was recovered in Portland shortly after the incident.
In a “Safety Alert for Operators” issued Sunday, the FAA said some operators had already begun additional inspections on the 737-900ER door plugs and “have noted findings with bolts during maintenance inspections.”
The alert does not elaborate what those findings revealed.
The FAA did not announce any intention to ground the 737-900ER on Sunday.
Boeing, and specifically its MAX aircraft, have been scrutinized in recent years. Both MAX models currently in service, the MAX 8 and MAX 9, were grounded globally in 2019 following two deadly MAX 8 crashes.
Boeing has pledged to “help address any and all findings” as airlines begin inspecting other MAX 9 planes and has said it will comply with regulatory investigations.
On Sunday evening, a Boeing spokesperson told Reuters in an email that “we fully support the FAA and our customers in this action.”
