As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ATL - FLT 2403 - ON CLIMB-OUT FROM ATL, EN ROUTE TO PHL, CREW REPORTED THE AIRCRAFT WOULD NOT PRESSURIZE IN ANY PRESSURIZATION MODE. FLIGHT RETURNED TO FIELD AT ATL AND LANDED WITHOUT FURTHER INCIDENT. NO EMERGENCY WAS DECLARED. MAINTENANCE FOUND THE AFT RIGHT SERVICE DOOR NOT SEALING PROPERLY. (M)