Bolts that helped secure a panel to the frame of a Boeing 737 Max 9 were missing before the panel blew off the Alaska Airlines plane last month, according to accident investigators. The National Transportation Safety Board said Tuesday a preliminary report on the Jan. 5 incident that the lack of certain damage on the plane indicates that all four bolts were missing before the plane took off from Portland, Oregon, the AP reports. Without the bolts, nothing prevented the panel from sliding upward and detaching from "stop pads" that secured it to the airframe. The Alaska Airlines pilots were forced to make a harrowing emergency landing with a hole in the side of the plane, but no serious injuries were reported.
The NTSB report included a photo from Boeing, which worked on the panel called a door plug, that showed that three of the four bolts that prevent the panel from moving upward are missing. The location of a fourth bolt is obscured by insulation. The preliminary report said the plane arrived at Boeing's factory near Seattle with five damaged rivets near the door plug, which had been installed by supplier Spirit AeroSystems. A Spirit crew replaced the rivets, which required removing the four bolts and opening the plug. The report did not say who removed the bolts. It said that a text message between Boeing employees who finished working on the plane after the rivet job included the photo showing the plug with missing bolts.
Democratic Sen. Tammy Duckworth, was upset at Boeing's lack of documentation about who did what and when the bolts went missing. "They didn't write any of this down," she told the AP. "It is very much Boeing's responsibility, absolutely, but I'm concerned that we may have multiple points of failure here." The NTSB did not declare a probable cause for the accident—that will come at the end of an investigation that could last a year or longer. "Whatever final conclusions are reached, Boeing is accountable for what happened," CEO David Calhoun said in a statement. "An event like this must not happen on an airplane that leaves our factory. We simply must do better for our customers and their passengers."
(More
Boeing stories.)