What was found
(CAN) FOLLOWING AN UNEVENTFUL LANDING AND WHILE TAXING AFTER THE LANDING ROLL OUT, THE CREW ENCOUNTERED A BRAKE FAILURE AND HAD TO APPLY THE EMERGENCY BRAKE IN ORDER TO STOP THE AIRCRAFT. MAINTENANCE TROUBLESHOOTING AND INSPECTION OF THE SYSTEM DETERMINED THAT THE POWER BRAKE -ANTI SKID VALVE ASSEMBLY HAD FAILED. THE VALVE ASSY WAS REPLACED AND ALL TESTS CONDUCTED IN ACCORDANCE WITH THE MM AND THE AIRCRAFT RELEASED.