The fuselage is manufactured in Kansas before being shipped by rail to Washington for final fit-out and assembly. The door plugs are put in place in Kansas, but not tightened down to flight spec because it’s expected that Boeing will take them off again to fit out the interior, then bolt them down to spec. One theory I’ve heard is that Boeing’s not using the plug doors to move in seats and lavatories and what have you, and no one thought to double check the plug doors afterwards in Washington because no one has touched them since it arrived from Kansas.
The fuselage is manufactured in Kansas before being shipped by rail to Washington for final fit-out and assembly. The door plugs are put in place in Kansas, but not tightened down to flight spec because it’s expected that Boeing will take them off again to fit out the interior, then bolt them down to spec. One theory I’ve heard is that Boeing’s not using the plug doors to move in seats and lavatories and what have you, and no one thought to double check the plug doors afterwards in Washington because no one has touched them since it arrived from Kansas.