What was found
FLT 779 JFK-MBJ RETURNED TO JFK, ON TAKEOFF CREW HAD A SKIN AIR VALVE FAULT FOLLOWED BY AND ECAM MESSAGE QRH RESET WAS UNSUCCESSFUL AND COULD NOT PRESSURIZE. LAST LEG INDICATES SKIN AIR OUTLET VALVE FAULT, AVEC TEST NOT PASSING. VALVE STAYS OPEN. REMOVED AND REPLACED SKIN AIR OUTLET VALVE IAW AMM 21-26-53-04, TEST PASS OPS GOOD.