As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX - FLIGHT 2512, AFTER TAKEOFF AIRCRAFT WOULD NOT PRESSURIZE. RETURNED TO THE FIELD AND ACCOMPLISHED A UNEVENTFUL LANDING. MAINTENANCE FOUND THE REAR CARGO DOOR NOT SEALED CORRECTLY. CORRECTLY SHUT DOOR AND PERFORMED OPERATIONAL CHECK OF DOOR AND PRESSURIZATION WITH NO DEFECTS NOTED. AIRCRAFT RETURNED TO SERVICE. NO PARTS REPLACED.