LOSS OF ACFT CTL IN TAXIING TFC RESULTS IN DAMAGE TO CPR SMT.

Narrative

GOING TO GREATER PIT TO PICK UP A PAX FOR MR Y; WHO ALSO OWNS THE ACFT. THE ACFT WE WERE GOING TO FLY IS AN SMT TWIN. AFTER CHKING THE WX; I PREFLTED THE AIRPLANE AND PREPARED THE CABIN FOR FLT. NOTHING UNUSUAL AT THIS POINT. I THEN CONTACTED ALTOONA FSS TO FILE A ROUND-ROBIN IFR FROM 2G3 TO PIT. MR X WAS FILED AS THE PIC. SINCE WE WERE NOT CARRYING PAX; I INTENDED TO FLY FROM THE L SEAT. I ASKED MR X TO GET THE BRAKES; WHILE I PULLED THE CHOCK. AFTER DOING THIS; I ENTERED THE ACFT AND PROCEEDED TO START THE ACFT; AFTER STARTING; WE TURNED ON ALL ELECTRICAL ITEMS ON THAT WERE ESSENTIAL TO THE FLT. OUR INTENTIONS WERE TO PICK UP OUR IFR CLRNC IN THE AIR. I STARTED TO TAXI THE AIRPLANE DOWN THE RAMP; HIT THE BRAKES; THE ACFT LUNGED FORWARD; AND I PROCEEDED TO TAXI TO RWY 23; AT 2G3; TO THE RUN-UP AREA. AT ABOUT 2/3 OF THE TAXIWAY; WHICH HAS AN UPSLOPE OF 3 DEGS; THE AIRPLANE WENT TO THE R. I ATTEMPTED TO CORRECT THIS BY L RUDDER AND BRAKE. THERE WASN'T ANY L BRAKE. I ATTEMPTED DIFFERENTIAL PWR FROM THE R ENG; TO NO AVAIL. IT HAPPENED IN APPROX 2 SECONDS. I CHOPPED THE THROTTLES AND TRIED BOTH BRAKES. THE ACFT CONTINUED OFF THE TAXIWAY TO THE R AND ONTO A GRASSY AREA. THE NOSE WHEEL COLLAPSED TO THE L OF THE ACFT AND THE PROPS DUG INTO THE SOD AND STOPPED. I SHUT OFF ALL ELECTRICAL ITEMS AND EXITED THE AIRPLANE. FROM ASSISTANCE FROM THE FBO PERSONNEL; WE PLACED BARRELS UNDER THE TIP TANKS TO CAPTURE FUEL FROM THE TIPS OVERFLOW. I WENT TO THE FBO AND CALLED THE FAA. A REPRESENTATIVE OF OPS AND AN FAA MECH CAME TO INVESTIGATE. THEY FOUND THE L BRAKE RESERVOIR TO BE COMPLETELY DRY; NO FLUID WAS LOCATED ON THE L BRAKE. THEY DESCRIBED THIS AS A MAINT FUNCTION. I HAD NO KNOWLEDGE OF ANY BRAKE PROBLEMS PRIOR TO THIS.