What was found
(CAN) REF. SDR NR 20060907002 RT BRAKE LOCKED-UP PREVIOUS SDR SUBMITTED MENTIONED THE PARK BRAKE VALVE AS THE UNSERVICEABLE PART, HOWEVER THE NEXT FLIGHT THE BRAKES ON THE RT SIDE LOCKED-UP AGAIN, BRAKES INSPECTED, PRESSURE RELIEVED AND AIRCRAFT RETURNED TO BASE FOR TROUBLSHOOTING, FOUND CO-PILOT RT BRAKE MASTER CYLINDER TRAPPING PRESSURE IN THE SYSTEM, BRAKE CYLINDER REMOVED AND EXAMINED, FOUND O-RING ON CHECK VALVE CUT, O-RINGS IN MASTER CYLINDER REPLACED WITH NEW, FUNCTION TEST CARRIED-OUT, BRAKES OPERATED NORMALLY (O-RING P/N MS28775-011) (TC NR 20060908002)