Narrative:

Original dispatch had 2 MEL's (tray table in row 22 inoperative and forward outflow valve failed open). During preflight walkaround inspection, I noticed the left pac (pressurization controller) on left side of aircraft bay open and maintenance technician working on pac. He said pac had blown duct and would be MEL'ed. I notified the captain upon my return to the cockpit and looked up inoperative pac in MEL book. The captain called dispatch for an amended release and asked them to doublechk the maximum allowable altitude with current MEL's. 5 mins prior to push, an amended release was brought to the cockpit with FL250 listed as maximum altitude with 1 pac inoperative. It was my leg to fly, and taxi out/takeoff were uneventful. Passing FL220 en route to FL240, I did a quick check of the overhead panel and noticed cabin altitude was approaching 10000 ft and increasing at 1000 FPM. I brought this to the captain's attention and asked him to get a lower altitude. Cabin altitude increased to a maximum of 10500 ft before reversing. Return to mci and landing was uneventful. Supplemental information from acn 365380: maximum allowable altitude on dispatch release should have stated FL200, but erroneously stated FL250. Was unable to maintain cabin altitude below 10000 ft pressure altitude. Declared an emergency with ATC and returned to mci.

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Original NASA ASRS Text

Title: B737 DISPATCHED WITH FORWARD OUTFLOW VALVE INOP MEL'ED AND L AIR CONDITIONING COMPRESSOR INOP MEL'ED. CREW ASKED DISPATCH FOR MAX ALT ON NEW EQUIP RELEASE AND IT WAS SHOWN AS 25000 FT INSTEAD OF THE LEGAL 20000 FT. AT FL220 CABIN WAS LOSING PRESSURE. EMER DECLARED AND RETURNED TO MCI.

Narrative: ORIGINAL DISPATCH HAD 2 MEL'S (TRAY TABLE IN ROW 22 INOP AND FORWARD OUTFLOW VALVE FAILED OPEN). DURING PREFLT WALKAROUND INSPECTION, I NOTICED THE L PAC (PRESSURIZATION CTLR) ON L SIDE OF ACFT BAY OPEN AND MAINT TECHNICIAN WORKING ON PAC. HE SAID PAC HAD BLOWN DUCT AND WOULD BE MEL'ED. I NOTIFIED THE CAPT UPON MY RETURN TO THE COCKPIT AND LOOKED UP INOP PAC IN MEL BOOK. THE CAPT CALLED DISPATCH FOR AN AMENDED RELEASE AND ASKED THEM TO DOUBLECHK THE MAX ALLOWABLE ALT WITH CURRENT MEL'S. 5 MINS PRIOR TO PUSH, AN AMENDED RELEASE WAS BROUGHT TO THE COCKPIT WITH FL250 LISTED AS MAX ALT WITH 1 PAC INOP. IT WAS MY LEG TO FLY, AND TAXI OUT/TKOF WERE UNEVENTFUL. PASSING FL220 ENRTE TO FL240, I DID A QUICK CHK OF THE OVERHEAD PANEL AND NOTICED CABIN ALT WAS APCHING 10000 FT AND INCREASING AT 1000 FPM. I BROUGHT THIS TO THE CAPT'S ATTN AND ASKED HIM TO GET A LOWER ALT. CABIN ALT INCREASED TO A MAX OF 10500 FT BEFORE REVERSING. RETURN TO MCI AND LNDG WAS UNEVENTFUL. SUPPLEMENTAL INFO FROM ACN 365380: MAX ALLOWABLE ALT ON DISPATCH RELEASE SHOULD HAVE STATED FL200, BUT ERRONEOUSLY STATED FL250. WAS UNABLE TO MAINTAIN CABIN ALT BELOW 10000 FT PRESSURE ALT. DECLARED AN EMER WITH ATC AND RETURNED TO MCI.

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.