Investigators say bolts on Boeing jet missing before panel blew out mid flight

The door plug from Alaska Airlines Flight 1282 found in Portland, Oregon (National Transportation Safety Board via AP)

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 issued a preliminary report on the January 5 incident on Tuesday.