A B757 flight crew had 2 high altitude cabin pressurization failures on departure from mco.

Attributes
ACN	450691
Time
Date	199909
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : mco.airport
State Reference	FO
Altitude	msl single value : 37000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zjx.artcc
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 6000 flight time type : 1500
ASRS Report	450691
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : landed in emergency condition flight crew : declared emergency
Consequence	other
Supplementary
Problem Areas	Maintenance Human Performance Aircraft
Primary Problem	Aircraft

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.

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.