Narrative:

I replaced the aevc (aircraft pressurization control computer) as called out on the work control card. After replacing the aevc the system test reported that the avionics skin exhaust valve had failed. Since it was late in the day we had to defer the bad component. However; the deferral process differed from how the system had originally came in deferred. A valve referenced in the original deferral was mistaken and inoperative'ed in the new deferral process causing the non compliance. Since the wrong valve was deactivated the aevc would not pass the system test per the MEL reference prior to its flight out of XXX. The MEL was then properly complied with and the aircraft was allowed to fly without incident.

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Original NASA ASRS Text

Title: AN A320 WITH A DEFERRED ITEM ON THE PRESSURIZATION SYS WAS WORKED BY REPLACING THE PRESSURIZATION CTLR. FAILED TEST. FOUND INCORRECT VALVE LOCKED OUT DURING THE DEFERRAL SPECIAL PROC.

Narrative: I REPLACED THE AEVC (ACFT PRESSURIZATION CTL COMPUTER) AS CALLED OUT ON THE WORK CTL CARD. AFTER REPLACING THE AEVC THE SYS TEST RPTED THAT THE AVIONICS SKIN EXHAUST VALVE HAD FAILED. SINCE IT WAS LATE IN THE DAY WE HAD TO DEFER THE BAD COMPONENT. HOWEVER; THE DEFERRAL PROCESS DIFFERED FROM HOW THE SYS HAD ORIGINALLY CAME IN DEFERRED. A VALVE REFED IN THE ORIGINAL DEFERRAL WAS MISTAKEN AND INOP'ED IN THE NEW DEFERRAL PROCESS CAUSING THE NON COMPLIANCE. SINCE THE WRONG VALVE WAS DEACTIVATED THE AEVC WOULD NOT PASS THE SYS TEST PER THE MEL REF PRIOR TO ITS FLT OUT OF XXX. THE MEL WAS THEN PROPERLY COMPLIED WITH AND THE ACFT WAS ALLOWED TO FLY WITHOUT INCIDENT.

Data retrieved from NASA's ASRS site as of January 2009 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.