What was found
PHX - AIR TURNBACK - FLT 0081 - AFTER TAKEOFF FROM PHX EN ROUTE TO BWI DURING CLIMB ECAM INDICATED LOSS OF YELLOW HYDRAULIC PRESSURE AND FLUID. AIRCRAFT TURNED BACK TO PHX. MAINTENANCE FOUND THE 3150GP HYDRAULIC SOLENOID VALVE LEAKING AND REPLACED VALVE IAW 29-19-51-401. SERVICED YELLOW HYDRAULIC SYSTEM, PERFORMED ENGINE RUN, OPERATED BOTH HYDRAULIC SYSTEMS, LEAK AND OPERATIONAL CHECKS WERE GOOD. VENDOR TEARDOWN OF 3-2 WAY VALVE FOUND A DAMAGED SEAL ON THE PISTON CONFIRMING FAILURE OF UNIT. REPLACED SEALS, O-RINGS, PACKINGS, AND BACK-UP RINGS, RE-CERTIFIED UNIT IAW CMM 29-10-14.