Four bolts were missing from Boeing 737 before door plug blew off, NTSB says
Enlarge / Rows 25 and 26 in the Boeing plane that lost a door plug during flight. (credit: NTSB)
Four important bolts were missing from a Boeing 737 Max 9 that lost a passenger door plug during flight, the National Transportation Safety Board concluded in its investigation.
The NTSB's preliminary report issued today is consistent with earlier news reports stating that investigators believed the bolts were missing when the plane left Boeing's factory. The plane used by Alaska Airlines was forced to make an emergency landing on January 5 when the door plug-which is used instead of an emergency exit door-blew off the aircraft in mid-flight.
An absence of markings around the holes where bolts should have been installed was a key piece of evidence cited in the NTSB report: