Narrative:

Climbing through FL370, heard a muffled bang. Cabin altitude started to climb at 1500-2000 FPM. Declared emergency and did emergency descent to 10000 ft MSL, while turning south to return to mco. Approach and landing were normal and cabin pressure never climbed above 10000 ft. Postflt inspection revealed an aft cargo door seal had unseated and was dangling outside the cargo door. They reseated the seal and we departed mco a second time and started losing cabin pressure at FL340. We declared an emergency and repeated the process above, returning to mco. Postflt inspection revealed the same problem.

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Original NASA ASRS Text

Title: A B757 FLC HAD 2 HIGH ALT CABIN PRESSURIZATION FAILURES ON DEP FROM MCO.

Narrative: CLBING THROUGH FL370, HEARD A MUFFLED BANG. CABIN ALT STARTED TO CLB AT 1500-2000 FPM. DECLARED EMER AND DID EMER DSCNT TO 10000 FT MSL, WHILE TURNING S TO RETURN TO MCO. APCH AND LNDG WERE NORMAL AND CABIN PRESSURE NEVER CLBED ABOVE 10000 FT. POSTFLT INSPECTION REVEALED AN AFT CARGO DOOR SEAL HAD UNSEATED AND WAS DANGLING OUTSIDE THE CARGO DOOR. THEY RESEATED THE SEAL AND WE DEPARTED MCO A SECOND TIME AND STARTED LOSING CABIN PRESSURE AT FL340. WE DECLARED AN EMER AND REPEATED THE PROCESS ABOVE, RETURNING TO MCO. POSTFLT INSPECTION REVEALED THE SAME PROB.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.