The National Post reports in its Tuesday edition that more details are emerging about Friday's Alaska Airlines flight over Oregon in a Boeing 737 Max 9 whose "door plug" flew off as the plane was climbing to cruising altitude. An Associated Press dispatch to the Post says that the lost door plug was found Sunday near Portland in the backyard of a school teacher's home. Investigators will examine the plug, which is 66 by 121 centimetres and weighs 28.5 kilograms, for signs of how it broke free. The explosive rush of air damaged several rows of seats and pulled insulation from the walls. The cockpit door flew open and banged into a lavatory door. The force ripped the headset off the co-pilot and the pilot lost part of her headset. Two cellphones that appeared to have belonged to passengers on the flight were found on the ground. One was discovered in a yard, the other on the side of a road. Both were turned over to the National Transportation Safety Board. Investigators will not be able to hear what was going on in the cockpit during the flight. The cockpit voice recorder was taped over after two hours. The plane made it back to Portland, and regulators ordered the grounding of 171 of the 218 Max 9s in operation.