Investigators uncovered evidence that the mid-cabin door plug that blew out of an Alaska Airlines aircraft’s fuselage after takeoff in January had not been secured with any bolts at the time of the accident, USA Today reports, meaning basically nothing but friction was holding the panel in place over multiple flights.
After recovering the panel and its hardware, investigators realized the four points where the panel was supposed to be attached to the plane’s frame were peculiarly undamaged when they were inspected. The parts didn’t show the expected shearing or wear patterns indicative that the bolts broke off or loosened over time; the lack of damage indicates the bolts were never in place.