Portland, Oregon — Federal investigators said a door panel slid up before flying off an Alaska Airlines plane last week, and they were studying whether four nuts that were supposed to hold it in place might have been missing when the plane took off.
The comments Monday from the U.S. National Transportation Safety Board came shortly after Alaska and United Airlines said in separate statements that they had found loose parts in the panels of other Boeing 737 Max 9 aircraft.
“Since we began preliminary inspections on Saturday, We have found cases that seem related to installation problems in the door coverfor example nuts that needed to be tightened more,” said United, based in Chicago.
Alaska said that when it began checking its Max 9s, “initial reports from our technicians indicated that there were loose parts visible on some aircraft.”
The findings from investigators and companies increased pressure on Boeing to respond to growing concerns since Friday night’s terrifying incident. The cover covering a hole to install an emergency door fell off the plane while it was flying over Oregon at 16,000 feet (4,800 meters) altitude.
Boeing has called a virtual all-employee meeting on Tuesday about safety.
Door covers are installed where emergency exits would be located on Max 9s with more than 200 seats. Alaska and United have fewer seats on their Max 9s, so they replace the heavy doors with those panels.
The panels can be opened for maintenance work. The nuts prevent the mechanism to move the panels up from being activated when the plane is flying.
During Alaska Airlines Flight 1282 on Friday night, the guides on the top of one of the covers broke, allowing the entire panel to shift upward and lose contact with 12 “stops” that maintain the piece attached to the plane’s door frame, members of the Transportation Safety Board explained at a press conference in Portland.
The agency’s director, Jennifer Homendy, said the board was investigating whether the four nuts that help prevent the panel from moving were missing when the plane took off from Portland or if they were blown away “during the violent explosive decompression episode.”