decompression. in prepping their planes for faa mandated emergency inspections, alaska airlines and united airlines both report issues with door plugs on an undies closed number of grounded max 9s mechanics found some lose hardware was visible. united says it found possible door plug installation issues and bolts that need ed additionl tightening. investigators are searching for the door plug bolts from friday s incident, potentially key evidence. we have not yet recovered the four bolts that restrain it from its vertical movement, and we have not yet determined if they existed there. reporter: a max 9 door plug is secured by high air pressure inside the plane pushing 12 tabs on thehe door against matching tabs on the plane s frame. a total of four bolts at the top and bottom of the door can be