What was found
FLT 9 PHX - ORD - EMERGENCY LANDING - CREW RECEIVED ECAM MESSAGES "BRAKES AUTO BRK FAULT" AND "INOP SYS NORM BRK AUTO BRK". AN EMERGENCY WAS DECLARED AND THE AIRCRAFT LANDED WITHOUT INCIDENT. FAULTS WERE PRESENT IN CRUISE, ON DESCENT, APPROACH, LANDING AND TAXI IN. MAINTENANCE REPLACED THE NORMAL BRAKE SERVO VALVE 16GG IAW AIRBUS MAINTENANCE MANUAL 32-42-48-000-001.