Narrative:

At approximately 110 KTS, received warning. Continued takeoff and contacted maintenance control and dispatch recommended we return to phx. Declared an emergency and landed normally phx. Callback conversation with reporter revealed the following information: crew was flying an airbus A320 aircraft. They were dispatched with an 'avionics system fault' ECAM warning MEL'ed inoperative. The avionics rack has an outflow valve that is full open on the ground for proper avionics cooling. At liftoff, the valve either partially closes or fully closes depending on temperature. The aircraft cannot pressurize with this valve fully open. This valve did not close as it was supposed to leaving the aircraft unable to pressurize.

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Original NASA ASRS Text

Title: A320 CREW HAD AN ECAM 'COOLING VALVE AVIONICS' WARNING AFTER TKOF. ACFT COULD NOT PRESSURIZE.

Narrative: AT APPROX 110 KTS, RECEIVED WARNING. CONTINUED TKOF AND CONTACTED MAINT CTL AND DISPATCH RECOMMENDED WE RETURN TO PHX. DECLARED AN EMER AND LANDED NORMALLY PHX. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: CREW WAS FLYING AN AIRBUS A320 ACFT. THEY WERE DISPATCHED WITH AN 'AVIONICS SYS FAULT' ECAM WARNING MEL'ED INOP. THE AVIONICS RACK HAS AN OUTFLOW VALVE THAT IS FULL OPEN ON THE GND FOR PROPER AVIONICS COOLING. AT LIFTOFF, THE VALVE EITHER PARTIALLY CLOSES OR FULLY CLOSES DEPENDING ON TEMP. THE ACFT CANNOT PRESSURIZE WITH THIS VALVE FULLY OPEN. THIS VALVE DID NOT CLOSE AS IT WAS SUPPOSED TO LEAVING THE ACFT UNABLE TO PRESSURIZE.

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.