What was found
DURING TAXI, THE AIRCRAFT EXPERIENCED A COMPLETE BRAKE FAILURE. THE AIRCRAFT WAS STOPPED USING THE EMERGENCY BRAKE, AND RETURNED TO GATE WITHOUT INCIDENT. THE FO'S MASTER CYLINDER WAS REPLACED, ALONG WITH THE LOW-PRESSURE RESERVOIR AND THE METERING VALVE. THE LOW-PRESSURE SYSTEM WAS BLED, THE OPERATIONAL CHECK WAS GOOD, AND THE AIRCRAFT WAS RETURNED TO SERVICE.