As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PIT - FLT 856 - AFTER TAKEOFF FROM PIT, AIRCRAFT FAILED TO PRESSURIZE. A LOUD AIR NOISE WAS HEARD COMING FROM DOOR R1. FLIGHT RETURNED TO PIT AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE RE-INSTALLED THE R1 DOOR SEAL AND SECURED THE SERVICE DOOR. PRESSURE TESTED GOOD. (X)