TXWY EXCURSION AFTER BRAKE FAILURE EVIDENT. PLT ELECTS TO DEP ARPT WITH ACFT AS IS.

Narrative

WHILE TAXIING FOR TKOF AT PYM; I APPLIED THE BRAKES AND NOTICED THE NOSE WAS PULLING TO THE R. AS I APCHED THE TURN FROM THE TXWY TO THE RWY; THERE WAS AN AIRPLANE ON THE R IN THE RUN-UP AREA SO I DECIDED TO USE MINIMUM BRAKING TO PREVENT MY AIRPLANE FROM TURNING INTO THE DIRECTION OF THE PARKED AIRPLANE. I PLANNED TO STOP JUST AFTER PASSING THE PARKED AIRPLANE BUT THE POOR BRAKING ACTION CAUSED ME TO ROLL JUST PAST THE EDGE OF THE HARD SURFACE; ONTO THE HARD-PACKED DIRT. I THOUGHT THE PROB WAS DUE TO BRAKE FADE DUE TO THE FACT THAT THERE WAS A TAILWIND ON THE TXWY AND EVEN WITH THE ENGS AT IDLE; I HAD TO RIDE THE BRAKES TO TAXI SLOWLY. WHEN I STOPPED; I SEEMED TO HAVE PLENTY OF BRAKE PEDAL PRESSURE; SO I TAXIED BACK ONTO THE HARD SURFACE WITH NO PROB; AND WAS ABLE TO STOP SATISFACTORILY. SINCE THE BRAKES SEEMED TO BE WORKING OK; I THOUGHT THEY HAD COOLED OFF AND WOULD BE NO MORE PROB. I DEPARTED AND PLANNED TO HAVE THE BRAKE SYS CHKED WHEN I RETURNED HOME. WHEN I ARRIVED AT MY DEST; I NOTICED THE L BRAKE WAS INEFFECTIVE ON ROLLOUT AND CHKED THE WHEEL ASSEMBLY AFTER PARKING THE ACFT. THE PROB; I DISCOVERED; WAS DUE TO THE SEPARATION OF THE BRAKE DISK FROM THE WHEEL ASSEMBLY. THE DISK SECTION WAS HELD IN PLACE BY THE BRAKE CALIPER ASSEMBLY WHICH IS WHY I STILL HAD GOOD PEDAL PRESSURE. THE ACFT WAS GNDED FOR REPAIRS. JUDGEMENTAL FACTORS: I SHOULD NOT HAVE ASSUMED THE PROB WAS DUE TO OVERHEATING; ETC. THE ACFT SHOULD HAVE BEEN INSPECTED BEFORE DEPARTING THE ARPT. EVEN THOUGH I HAD BRAKING (APPARENTLY FROM THE R ONLY); I SHOULD HAVE MADE SURE THE ACFT WAS AIRWORTHY BEFORE FLT. FORTUNATELY; NO ONE WAS INJURED. THE NEXT TIME I HAVE A PROB; I WILL GET IT CHKED OUT RATHER THAN MAKING UNFOUNDED ASSUMPTIONS.