The Federal Aviation Administration (FAA) has issued a Safety Alert for Operators (SAFO) to airlines that fly Boeing 737-900ER jets urging them to check the aircraft’s mid-exit door plugs to ensure the door is properly secured.
According to a statement by the FAA on January 21, 2024, the Boeing 737-900ER mid-exit door plugs have an “identical door plug design to the 737-9 MAX”.
All 737 MAX 9 planes are currently grounded after a plug door separated from an Alaska Airlines fuselage shortly after takeoff from Portland International Airport (PDX) on January 5, 2024.
The FAA confirmed the purpose of the 737-900ER “visual inspections” was to add an extra “layer of safety”.
In the SAFO, the FAA said, “some operators have conducted additional inspections on the 737-900ER mid-exit door plugs and have noted findings with bolts during the maintenance inspections”.
The new inspections of 737-900ERs relate to the “four locations where a bolt/nut/pin installation is used to secure the door to the airframe”.
Operators are “encouraged to conduct a visual inspection to ensure the door plug is restrained from any movements through the two upper guide track bolts and two lower arrestor bolts,” the FAA said.
The Boeing 737-900ER is the largest variant of the Next Generation 737 family that was first introduced in 1997.
In the United States (US) operators of the 737-900ER include United Airlines, Alaska Airlines and Delta Air Lines.
On January 17, 2024, the FAA confirmed that Boeing had completed plug door inspections of 40 grounded 737 MAX 9 planes.
The FAA specifically asked for the checks after the initial inspection and maintenance instructions proposed by Boeing did not provide enough data.
The FAA will now “thoroughly” review the paperwork before any final inspections of the grounded aircraft can take place.
Boeing was required to set out an “extensive and rigorous inspection and maintenance process” for approval by the FAA before any of the grounded 737 MAX-9 aircraft can return to service.