AN A320 FLT CREW REPORTS THAT ON AFTER LANDING ROLLOUT THE AIRCRAFT MADE AN UNCOMMANDED RIGHT TURN; LEAVING THE RUNWAY BRIEFLY BEFORE THEY COULD REGAIN CONTROL.

Narrative

I AM NOT SURE WHY THE ACFT SUDDENLY TURNED TO THE R AND WHY THE RUDDER PEDAL STEERING OR NOSEWHEEL STEERING COULD NOT CORRECT IT. WE WERE INTENDING TO MAKE A TURN-OFF FURTHER DOWN THE RWY BECAUSE THERE WERE ACFT ON THE TXWY LINING UP FOR DEPS FOR RWY 9L BECAUSE THEY HAD JUST SWITCHED OVER TO E OPS. SO WE WERE NOT USING BRAKES AT THAT POINT BECAUSE WE WERE PLANNING TO TURN-OFF TO THE L FURTHER DOWN THE RWY. AFTER LNDG ON RWY 9R (FO'S LNDG) SLOWING THROUGH ABOUT 90 KTS; HE STOWED BOTH REVERSERS. SLOWING THROUGH ABOUT 60 KTS WE EXCHANGED CTL OF THE ACFT. SHORTLY AFTER THAT (ABOUT 5 SECONDS); THE ACFT TOOK A HARD R TURN. I TRIED TO CORRECT IT WITH BOTH RUDDER PEDAL AND NOSEWHEEL STEERING BUT NEITHER WERE EFFECTIVE. THE R MAIN GEAR AND NOSEWHEEL LEFT THE RWY SURFACE BRIEFLY UNTIL I WAS ABLE TO REGAIN CTL OF THE ACFT AND I BROUGHT IT BACK ONTO THE RWY TO A STOP. I THEN WAS ABLE TO TAXI OFF THE RWY AND TO THE GATE. WE WERE NOT SURE WHAT HAD HAPPENED. WE TOLD TWR THAT WE COULD HAVE POSSIBLY BLOWN A TIRE. AT THE GATE; MAINT CHKED THE MAIN GEAR AND FOUND TRACES OF DIRT ON THE R MAIN GEAR AND NOSEWHEEL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE REPORTER STATED THAT MAINTENANCE DETERMINED THAT SOME TYPE OF BRAKE SYSTEM FAULT WAS THE MOST PROBABLE CAUSE OF THE LOSS OF DIRECTIONAL CONTROL; ALTHOUGH IT APPEARS MAINTENANCE WAS UNABLE TO SPECIFICALLY IDENTIFY THE FAULT.