The Federal Aviation Administration recommended late Sunday night that airlines begin visual inspections of door plugs on Boeing 737-900ER planes, the second Boeing model to come under scrutiny this month.
The FAA said the plane had the same door plug design as the company's newer 737 Max 9. The agency grounded about 170 Max 9 jets after a door panel on one of the planes flew off shortly after an Alaska Airlines flight left Portland, Oregon, Jan. 5, forcing an emergency landing.
The door plugs are placed as a panel where an emergency door would otherwise be if an aircraft were equipped with more seats.
After grounding the Max 9 aircraft, the FAA subsequently announced it was investigating whether Boeing had failed to ensure the jet was safe and conformed to the agency's approved design.
The FAA said Sunday that the door plug on the 737-900ER, an earlier-generation model that is not part of Boeing's Max line, was not yet a problem.
“As an additional safety measure, the Federal Aviation Administration recommends that operators of Boeing 737-900ER aircraft visually inspect the door plugs in the center of the exit to ensure the door is properly secured,” the agency said in a statement.
The FAA recommends that airlines operating the 737-900ER immediately inspect the four locations where the door plug attaches to the airframe. According to the FAA, the 737-900ER has logged over 11 million operating hours and approximately four million flight cycles. Boeing delivered about 500 of these planes worldwide between 2007 and 2019, although not all of them have door plugs.
“We fully support the FAA and our customers in this action,” Boeing said in a statement.
Alaska Airlines and United Airlines, both of which operate the 737-900ER, said in statements that they had already begun inspecting the model in their fleets. Delta Air Lines, which also flies the plane, said it has “elected to take proactive steps to inspect our 737-900ER fleet.” None of the airlines expected disruptions to their operations.
The incident involving the Alaska Airlines 737 Max 9 flight this month did not result in serious injuries, but could have been far more serious had the plane been at cruising altitude. The National Transportation Safety Board is investigating the incident in hopes of determining what caused the door plug to fly from the plane.
Meanwhile, the FAA recently ordered an initial round of inspections for 40 of the grounded Max 9 aircraft as it works to finalize inspection instructions for the aircraft. The agency announced last week that those inspections had been completed and that it would review the data obtained from them.