As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT 37000 FT IN CRUISE, CABIN ALTITUDE CLIMBED RAPIDLY AND EXCEEDED 20,000 FEET. FOLLOWED QRH, CABIN WAS NOT CONTROLLABLE IN MAN AC W/ VALVE CLOSED INDICATION. AIRCRAFT RETURNED TO PAOM. PERFORMED CABIN DEPRESSURIZATION CONDITIONAL INSPECTION IAW AMM 05-51-081 FOUND LOWER AFT CARGO COMPT BLOW OUT PANEL BLOWN OUT. NO OTHER FAULTS FOUND, PERFORMED CABIN PRESSURE LEAK TEST IAW AMM 05-51-91 NO FAULTS FOUND.