What was found
ORD - ABORTED TAKEOFF - FLT 0654 - ON TAKEOFF AT ORD EN ROUTE FOR PHX RECEIVED YELLOW HYDRAULIC RESERVOIR LOW LEVEL INDICATION WITH ASSOCIATED BRAKE, ANTI-SKID, AND NOSE WHEEL STEERING FAULTS ON UPPER ECAM, REJECTED TAKEOFF BELOW 80 KTS. MAINTENANCE FOUND FLUID LEAKING FROM A CRACK IN THE POWER TRANSFER UNIT SOLENOID VALVE (1012GL) (2 WAY VALVE). REPLACED CRACKED VALVE IAW AMM 29-23-51-401. SERVICED YELLOW HYDRAULIC SYSTEM AND PERFORMED ENGINE RUN, OPERATIONAL AND LEAK CHECKS WERE GOOD. FUNCTIONAL TEST OF POWER TRANSFER UNIT SOLENOID VALVE S/N 0141 CONFIRMED FAILURE OF UNIT FOR INTERMITTENT OPENING AND CLOSING. REPLACED SEAL'S, O-RINGS, AND BACK UP RINGS, UNIT REPAIRED IAW CMM 29-10-12.