The Federal Aviation Administration recommended late Sunday that airlines begin visual inspections of door plugs on a second Boeing model.
The agency’s safety alert covers Boeing 737-900ER planes. The recommendation comes following an incident on Jan. 5 when a door panel on a Boeing 737 Max 9 flew off an Alaska Airlines jet shortly after it took off from Portland, Oregon. The plane made an emergency landing and no one was seriously injured.
The FAA has since grounded all Boeing 737 Max 9 aircraft operated by U.S. airlines or in U.S. territory.
While the Boeing 737-900ER planes have the same door plug design as the 737 Max 9, there have been no issues with the door panels, according to The New York Times.
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“As an added layer of safety, the Federal Aviation Administration is recommending that operators of Boeing 737-900ER aircraft visually inspect mid-exit door plugs to ensure the door is properly secured,” the agency said in a statement.
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Alaska Airlines, United Airlines and Delta Air Lines all use the 737-900ER.
All three airlines said they had already been checking the door plugs, the Times reported.
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The door plugs are panels placed where an emergency door would otherwise be if there were more seats on the plane.