Boeing Reinstalled Panel That Later Blew Out of 737 Max Jet

Nearly three weeks after a hole blew open on a Boeing 737 Max 9 during an Alaska Airlines flight, terrifying passengers, new details about the jet’s production are intensifying scrutiny of Boeing’s quality-control practices.

About a month before the Max 9 was delivered to Alaska Airlines in October, workers at Boeing’s factory in Renton, Wash., opened and later reinstalled the panel that would blow off the plane’s body, according to a person familiar with the matter.

The employees opened the panel, known as a door plug, because work needed to be done to its rivets — which are often used to join and secure parts on planes — said the person, who asked for anonymity because the person isn’t authorized to speak publicly while the National Transportation Safety Board conducts an investigation.

The request to open the plug came from employees of Spirit AeroSystems, a supplier that makes the body for the 737 Max in Wichita, Kan. After Boeing employees complied, Spirit employees who are based at Boeing’s Renton factory repaired the rivets. Boeing employees then reinstalled the door.

An internal system that tracks maintenance work at the facility, which assembles 737s, shows the request for maintenance but does not contain information about whether the door plug was inspected after it was replaced, the person said.

The details could begin to answer a crucial question about why the door plug detached from Flight 1282 at 16,000 feet, forcing the pilots to make an emergency landing at Portland International Airport in Oregon minutes after taking off on Jan. 5. The door plug is placed where an emergency exit door would be if a jet had more seats. To stay in place, the plug relies primarily on a pair of bolts at the top and another pair at