Narrative:

The aircraft was released with the left pack inoperative and the right pack placarded inoperative in automatic temperature range. We were told that it worked ok in manual after takeoff from den the aircraft was pressurizing at what appeared a near normal rate. However as we continued our climb the altitude of the cabin did not stop at its preset limit. I followed flight manual abnormal procedures and advised ATC that we needed a descent back to den. First officer was flying and I worked the problem. I observed minor altitude deviations on his descent back to den. We burned off fuel below landing weight and made a normal landing at den. In summary: I have serious doubts about the operation of the right pack that was released by maintenance. It is apparent that maintenance wanted to release the aircraft west/O, I feel, really checking into a possible problem. Callback conversation with reporter revealed the following: reporter indicated that the left pack was operating normally on the previous flight leg and was found to be inoperative during his preflight. The MEL stated dispatch altitude restriction of 25000'. Prior to takeoff automatic pressurization control was set for FL250. During climb through 10000' the cabin altitude passed through 7500'. A short time later the outflow valves were manually closed and the aircraft climbed through 15000' with the cabin climbing through 10000'. Descent was started at this time. Aircraft was flown at various lower altitudes east of den by the first officer. Minor altitude deviations during this period were caused by first officer distraction, 100-150' from assigned altitude. After returning to gate, the flight was cancelled. The aircraft spent the night and both packs were repaired. Reporter is concerned with a conversation during his preflight that indicated that maintenance had worked on the right pack with no log book entries. He thought the company was keeping separate records for maintenance items.

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Original NASA ASRS Text

Title: RETURN LAND BECAUSE UNABLE TO PRESSURIZE ACFT.

Narrative: THE ACFT WAS RELEASED WITH THE LEFT PACK INOP AND THE RIGHT PACK PLACARDED INOP IN AUTO TEMP RANGE. WE WERE TOLD THAT IT WORKED OK IN MANUAL AFTER TKOF FROM DEN THE ACFT WAS PRESSURIZING AT WHAT APPEARED A NEAR NORMAL RATE. HOWEVER AS WE CONTINUED OUR CLB THE ALT OF THE CABIN DID NOT STOP AT ITS PRESET LIMIT. I FOLLOWED FLT MANUAL ABNORMAL PROCS AND ADVISED ATC THAT WE NEEDED A DSCNT BACK TO DEN. F/O WAS FLYING AND I WORKED THE PROB. I OBSERVED MINOR ALT DEVIATIONS ON HIS DSCNT BACK TO DEN. WE BURNED OFF FUEL BELOW LNDG WT AND MADE A NORMAL LNDG AT DEN. IN SUMMARY: I HAVE SERIOUS DOUBTS ABOUT THE OPERATION OF THE RIGHT PACK THAT WAS RELEASED BY MAINT. IT IS APPARENT THAT MAINT WANTED TO RELEASE THE ACFT W/O, I FEEL, REALLY CHKING INTO A POSSIBLE PROB. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR INDICATED THAT THE LEFT PACK WAS OPERATING NORMALLY ON THE PREVIOUS FLT LEG AND WAS FOUND TO BE INOP DURING HIS PREFLT. THE MEL STATED DISPATCH ALT RESTRICTION OF 25000'. PRIOR TO TKOF AUTO PRESSURIZATION CONTROL WAS SET FOR FL250. DURING CLB THROUGH 10000' THE CABIN ALT PASSED THROUGH 7500'. A SHORT TIME LATER THE OUTFLOW VALVES WERE MANUALLY CLOSED AND THE ACFT CLBED THROUGH 15000' WITH THE CABIN CLBING THROUGH 10000'. DSCNT WAS STARTED AT THIS TIME. ACFT WAS FLOWN AT VARIOUS LOWER ALTS E OF DEN BY THE F/O. MINOR ALT DEVIATIONS DURING THIS PERIOD WERE CAUSED BY F/O DISTR, 100-150' FROM ASSIGNED ALT. AFTER RETURNING TO GATE, THE FLT WAS CANCELLED. THE ACFT SPENT THE NIGHT AND BOTH PACKS WERE REPAIRED. RPTR IS CONCERNED WITH A CONVERSATION DURING HIS PREFLT THAT INDICATED THAT MAINT HAD WORKED ON THE RIGHT PACK WITH NO LOG BOOK ENTRIES. HE THOUGHT THE COMPANY WAS KEEPING SEPARATE RECORDS FOR MAINT ITEMS.

Data retrieved from NASA's ASRS site as of August 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.