AN AIRBUS 320 WAS DISPATCHED IN NON COMPLIANCE WITH THE SKIN AIR OUTLET VALVE DEFERRED PER THE MEL IMPROPERLY. MEL PROCEDURE WRONG.

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WE HAD AN INCIDENT IN OUR AIRLINE TODAY WHERE WE HAD TO PLACE AN MEL ON AN AIRBUS FOR A FAULTY SKIN AIR OUTLET (EXTRACT) VALVE. I HAD NOT DONE THIS VALVE BEFORE BUT HAD PLACED MEL'S ON SIMILAR VALVES. THIS PROB CAME UP AROUND DEP TIME SO THERE WAS AN ADDED SENSE OF PRESSURE. IN THE MEL BOOK UNDER 21-2604 WE FOLLOWED THE PROCS AND DISPATCHED THE ACFT; AFTER DEPARTURE THE ACFT COULD NOT PRESSURIZE AND WROTE SO IN THE LOGBOOK. WE FOUND OUT THAT STEP 5 IN OUR MEL BOOK IS LABELED WRONG. IT SAYS TO TURN THE HANDLE CLOCKWISE UNTIL THE INTERNAL FLAP IS FULLY OPEN. WHERE IN REALITY THE HANDLE MUST BE TURNED COUNTERCLOCKWISE TO CAUSE THIS TO HAPPEN. SO THE FOLLOWING NOTE THAT DESCRIBES THE VALVE MOVEMENT WITH THE HANDLE IN THE NEXT STEP WAS MISINTERPRETED BY US CAUSING THE VALVE TO BE OPEN AND THUS CAUSING THE UNPRESSURIZED CONDITION. WE ARE GETTING TOGETHER WITH OUR TECH CENTER TO MAKE THEM AWARE OF THIS MISPRINT IN THE MEL MANUAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT USING THE MEL SPECIAL PROCEDURE FOR RENDERING THE SKIN AIR OUTLET VALVE INOPERATIVE IS NOT CORRECT. THE RPTR SAID STEP 5 IS WRONG AND WILL CAUSE THE CABIN NOT TO PRESSURIZE AS THE VALVE WILL BE OPEN. THE RPTR STATED TECHNICAL PUBLICATIONS HAS BEEN ADVISED OF THE NEED FOR REVISION.