Boeing investigation focuses on door panel as carriers find loose parts

Air-safety officials probing last week’s fuselage blowout on a Boeing Co. 737 aircraft have turned their attention to four bolts they’ve been unable to locate and said they may widen their investigation beyond the Max 9 variant after multiple airlines found loose parts.

The bolts were meant to secure the door panel that suddenly broke loose on Jan. 5, when Alaska Airlines Flight 1282 was climbing toward cruising altitude with 171 passengers aboard. Tightened properly, they prevent the panel from sliding upward past the 12 stopper tabs that bind it to the aircraft’s fuselage.