What was found
CREW REPORTED UNABLE TO PRESSURIZE AIRPLANE IN FLIGHT. FLIGHT CREW RETURNED AND MADE AN UNEVENTFUL OVERWEIGHT LANDING. AS A RESULT OF THE FLIGHT CREW DISCREPANCY, MAINTENANCE TROUBLESHOOTING AND INSPECTION REVEALED LEAKAGE AT THE FUSELAGE C-1 DOOR CUTOUT SEAL. MAINTENANCE PROCEEDED TO REMOVE AND REPLACE THE DAMAGED SEAL AS REQUIRED PER MM AND PERFORMED A PRESSURIZATION AND AIRCRAFT PRESSURIZED ON GROUND TO 6.0 PSI. AC PRESSURIZATION SYSTEM ALL LEAK AND OPERATIONALLY CHECKED NORMAL IAW MM. AIRCRAFT WAS RETURNED TO SERVICE.