As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHL - FLT 451 - UNABLE TO PRESSURIZE AIRCRAFT. FOLLOWED ALL USAIR PROCEDURES, NO HELP. F/A ADVISED IN PHL THAT THE DOOR WAS HARD TO SHUT. ALSO, HAD TO SHUT DOWN AND RESTART LEAVING DCA PRIOR TO STARTING ENGINE. THERE WAS A PRESSURE BUMP. FOUND CABIN DOOR NOT PROPERLY CLOSED. FALSE LOCK INDICATION. OPS CHECK DOOR OPERATION. OPS CHECK GOOD. PRESSURIZED AIRCRAFT AND INSPECTED DOOR. OPS CHECK GOOD. (X)