BA-46 ROLLED IT THE TERMINAL AFTER WHEEL CHOCKS WERE REMOVED.

Narrative

ACFT WAS READY TO TAXI AFTER COMPLETING ALL CHECKLISTS. CHOCKS WERE REMOVED AND I WAS CHECKING THE AREA FOR A R TURN OUT. I NOTICED THE ACFT WAS ROLLING BUT NOT TURNING OUT. LOOKING BACK INSIDE I OBSERVED THE CAPT ATTEMPTING TO STOP. AS WE CLOSED ON THE TERMINAL I SUGGESTED OUT LOUD USING THE 'PUSH EMER YELLOW SYS.' LOOKING AT THE BRAKE CONTROL HANDLE I OBSERVED IT TO BE IN THE 'PUSH EMER YELLOW SYS' AND STILL NO BRAKING. THE CAPT VERY QUICKLY SELECTED ALL ENGS TO FUEL OFF JUST PRIOR TO HITTING THE TERMINAL BOARDING GATE DOOR. THE ACFT ROLLED BACKWARDS APPROX 6' AND CAME TO A STOP. CAPT CHECKED WITH THE 'A' FLT ATTENDANT IF THERE WERE ANY INJURIES. THERE WERE NONE. HE THEN MADE A PA TO THE PAX WHILE I CALLED COMPANY FOR ASSISTANCE. NORMAL DEPLANING FOLLOWED AND THE FLC SECURED THE ACFT. THERE ARE THREE HYD SYS ON THIS ACFT. ALL WERE POWERED AND SHOWING NORMAL PRESSURE. THE START OF ROLLING WAS WITH THE PARKING BRAKE SET AND NORMAL BRAKE PRESSURE INDICATED. NO CAUSE HAS BEEN FOUND YET. LAST ITEM BEING CHECKED IS THE ANTI-SKID COMPUTER BOX WHICH HAD TO BE SENT OUT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: PLT REPORTS THAT THE TESTING OF THE ANTI-SKID CTLR IS NOT YET COMPLETE. IT WAS POINTED OUT THAT FOUR ADDITIONAL BRAKE FAILURES HAVE OCCURRED. THESE RESULTED IN THE ACFT STARTING TO ROLL WHEN THE CHOCKS WERE REMOVED. ALL THESE OCCURRED AFTER HYD FLUID TRANSFER WAS INITIATED BY THE CREW. THE PLT'S ACR HAS POSTED A BULLETIN TO CREWS PROHIBITING HYD FLUID TRANSFER. THE ACFT MUST BE SERVICED EXTERNALLY BY MAINT PERSONNEL.