Narrative:

Climbing out of FL240, crew heard a pop from the rear of the aircraft. The cabin started climbing 1500-2000 FPM. I tried to control the cabin manually and with flow control, which reduced the cabin rate of climb to 1000 FPM. The captain/first officer requested to level at FL250 to try to correct the problem. We leveled and could not correct the problem. The cabin altitude at this time was about 10000'. The crew went on O2. We contacted. Maintenance control and were instructed to return to louisville. The captain directed the first officer to contact ATC for clearance direct louisville and a lower altitude. We were granted both, descent to 11000'. I was able to bring the cabin back below 10000' and we requested a fuel dump area from ATC. Our maximum landing weight is 275000#, so we needed to get rid of 13000 pounds of fuel. We were given the ok to dump by our operations and ATC. We ran the appropriate checklists and commenced the dump. Fuel dump and all checklists were completed. Center handed us off to louisville approach for vectors to the ILS 19 approach. On approach we experienced a slight split flap condition. The captain trimmed out opposing forces and landed west/O incident. Below 10000' we talked about the problem and various questions about the dump and return, possibly stretching the sterile cockpit rule, although all conversation was concerning our problems.

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Original NASA ASRS Text

Title: HVT HAD TO DESCEND AND RETURN LAND BECAUSE THEY LOST CTL OF THE PRESSURIZATION SYSTEM.

Narrative: CLBING OUT OF FL240, CREW HEARD A POP FROM THE REAR OF THE ACFT. THE CABIN STARTED CLBING 1500-2000 FPM. I TRIED TO CTL THE CABIN MANUALLY AND WITH FLOW CTL, WHICH REDUCED THE CABIN RATE OF CLB TO 1000 FPM. THE CAPT/F/O REQUESTED TO LEVEL AT FL250 TO TRY TO CORRECT THE PROB. WE LEVELED AND COULD NOT CORRECT THE PROB. THE CABIN ALT AT THIS TIME WAS ABOUT 10000'. THE CREW WENT ON O2. WE CONTACTED. MAINT CTL AND WERE INSTRUCTED TO RETURN TO LOUISVILLE. THE CAPT DIRECTED THE F/O TO CONTACT ATC FOR CLRNC DIRECT LOUISVILLE AND A LOWER ALT. WE WERE GRANTED BOTH, DSNT TO 11000'. I WAS ABLE TO BRING THE CABIN BACK BELOW 10000' AND WE REQUESTED A FUEL DUMP AREA FROM ATC. OUR MAX LNDG WT IS 275000#, SO WE NEEDED TO GET RID OF 13000 LBS OF FUEL. WE WERE GIVEN THE OK TO DUMP BY OUR OPS AND ATC. WE RAN THE APPROPRIATE CHKLISTS AND COMMENCED THE DUMP. FUEL DUMP AND ALL CHKLISTS WERE COMPLETED. CENTER HANDED US OFF TO LOUISVILLE APCH FOR VECTORS TO THE ILS 19 APCH. ON APCH WE EXPERIENCED A SLIGHT SPLIT FLAP CONDITION. THE CAPT TRIMMED OUT OPPOSING FORCES AND LANDED W/O INCIDENT. BELOW 10000' WE TALKED ABOUT THE PROB AND VARIOUS QUESTIONS ABOUT THE DUMP AND RETURN, POSSIBLY STRETCHING THE STERILE COCKPIT RULE, ALTHOUGH ALL CONVERSATION WAS CONCERNING OUR PROBS.

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.