What was found
PHX - AIR TURNBACK - FLT 0071 - ON CLIMBOUT, EN ROUTE. THE RT ENG ANTI-ICE COWL VALVE OPEN LIGHT REMAINED INTRANSIT, VALVE NEVER OPENED OR INDICATED A DECREASE IN DUCT PRESSURE. TURNED BACK & LANDED WITHOUT FURTHER EVENT. MAINT R & R RT ENG INLET COWL THERMAL ANTI-ICE VALVE IAW BMM 30-21-11, OPERATIONAL CHECK GOOD. INDUCTION TEST OF ENG INLET COWL THERMAL ANTI-ICE VALVE CONFIRMED FAILURE OF UNIT FOR EXCESSIVE PORT & CASE LEAKAGE, & LOW REGULATION. DISASSY OF UNIT FOUND BOTH FLOW BODIES, SEALS, DIAPHRAGM, POPPET ASSY, & RING WORN BEYOND LIMITS. REPLACED FLOW BODIES, SEALS, DIAPHRAGM RING. BUSHINGS , BEARINGS, POPPET ASSY, & MINOR HARDWARE. UNIT FUNCT TESTED & RETURNED TO SERVICE.