As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TUL INFLIGHT AIRCRAFT LOST CABIN PRESSURE AT 28,000 FEET. OXYGEN MASKS DEPLOYED. RETURNED TO TUL AND LANDED WITHOUT INCIDENT. FOUND OUTFLOW VALVE DOOR DETACHED FROM AIRCRAFT. ONLY SMALL SECTION OF HINGED AREA REMAINED. REPLACED OUTFLOW VALVE AND OXYGEN GENERATOR AND MASKS. SYSTEM GROUND CHECKED NORMAL OPERATION.