What was found
LAS-SNA - FLT NR 1855 - DURING CLIMB THE CABIN ALTITUDE BEGAN CLIMBING RAPIDLY. CREW UNABLE TO CONTROL WITH MANUAL OR STANDBY. LEFT BLEED INDICATED 0 PSI. CREW RETURNED AIRCRAFT TO LAS WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND TWELVE INCHES OF AFT CARGO DOOR SEAL HANGING OUT OF DOOR. MAINTENANCE ALSO FOUND NR 1 ENG MUSCLE AIR LINE AT PRSOV LEAKING. REINSTALLED AFT CARGO DOOR SEAL AND REPLACED NR 1 ENGINE MUSCLE AIR LINE AND 450 DEGREE THERMOSTAT. REF AWXA9500494.