>>1971927That's the gist of it.
The inside of the fuselage almost always has a higher pressure than the outside air. Doors and plug panels like the one involved in this event rest on the frames inside the fuselage so the higher internal pressure seals them shut. It's why you can't open a door in flight unless you have the gorilla strength to oppose the 7 PSI pushing the entire area of the door into its frame.
The doors that swing out lock by a mechanism that swings the door in and down (or up sometimes) so that the stop fingers line up and function on the same principle as above. (forgive the crude diagram)
