Investigators are analyzing the safety door (plug door) that burst on the left side of a B-737 Max 9 aircraft (registration N704AL), operated by Alaska Airlines (flight AS1282), while it was in flight, at approximately 16,000 feet of altitude. The incident occurred on Friday 5 January, immediately after takeoff from Portland airport, forcing the commander to make a dramatic emergency landing.

How could all this happen? Technicians from the National Transportation Safety Board (NTSB) began analyzing the tailgate, found in the garden of a house in Portland. The agency's engineer, Clint Crookshanks, reported that all 12 "stop fittings" on the plug door came loose during the incident and that the four bolts (two in the top corners, two in the brackets of the lower hinges) which prevent the vertical movement of the door have not been recovered yet.

NTSB said it will not be able to determine whether the safety door was properly secured but will be able to determine, by examining the marks on the plug door, whether the four bolts were present.

To date, at least two airlines have already discovered that the bolts used to secure that panel were loose. In the Alaska Airlines case, according to Crookshanks "the door moved upwards and came loose from the fasteners, breaking the stop fittings" with the fuselage made by the company Spirit AeroSystems.

On the same topic, see also the article published by AVIONEWS.