What was found
EN ROUTE, CREW OBSERVED A GREEN HYD SYS OVERHEAT MESSAGE ON ECAM & PROCEEDED WITH ECAM ACTIONS. FLT RETURNED TO PHX WHERE MX PERFORMED A GREEN HYD SYS INTERNAL LEAKAGE TEST IAW TSM 29-00-00-280-001. MAINT DISCOVERED MLG SELECTOR VALVE BYPASSING HEAVILY & PROCEEDED TO REMOVE & REPLACE MLG SELECTOR VALVE & MLG DOOR SELECTOR VALVE IAW AMM 32-31-34, AMM 32-31-12 & AMM 32-31-00. LEAK & OPERATIONAL TESTS GOOD. VENDORS PRE-TEST OF MLG SELECTOR VALVE CONFIRMED FAILURE OF UNIT FOR EXTERNAL LEAKAGE, RESEALED UNIT PER CMM 32-31-34, VENDORS PRE-TEST OF MLGDOOR SELECTOR VALVE P/N 114079016, S/N CWDD-DH 48-99 ALSO CONFIRMED FAILURE OF UNIT FOR INTERNAL LEAKAGE. UNIT REPAIRED IAW CMM 32-31-34 BY REPLACING 2 EACH PISTON SEA