THE NOSE GEAR STEERING ON AN ACR LTT FAILED SENDING THE ACFT INTO SOME SNOW. THERE WAS NO DAMAGE.

Narrative

WE WERE VECTORED FOR AN ILS 15R CIRCLE TO 4L APCH AT BOS. WX CONDITIONS WERE 900 SCATTERED 1500 OVCST; WIND 320 DEGS AT 10 KTS. UPON LNDG; THE ACFT WAS SLOWED TO APPROX 70 KTS AND THE CREW TRANSITIONED FROM FO FLYING TO CAPT. THE CAPT CALLED FOR THE SPD LEVERS LOW. THIS ALLOWS THE HYD NOSEWHEEL STEERING TO BE ARMED. IT WAS AT THIS TIME WE HAD AN UNCOMMANDED NOSEWHEEL STEERING TURN HARD L AND WE LEFT THE RWY AND ENDED UP ON A PAVED ISLAND AND STOPPED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE LTT HAD BEEN WORKED ON AT BGR AND THE NOSE STEERING TESTED PROPERLY AT THAT TIME. ON ROLLOUT AT BOS; THE NOSE GEAR STEERING 'TOOK OFF' PUTTING THE ACFT OFF THE RWY INTO SOME SNOW. THERE WAS NO DAMAGE TO THE ACFT OR THE ARPT. MAINT CHANGED SOME OF THE ELECTRONIC COMPONENTS IN THE SYS INCLUDING A POTENTIOMETER. THIS IS AN ONGOING PROB WITH THIS ACFT. THE RPTR STATES THAT THIS HAS NOT HAPPENED TO HIM BEFORE; BUT HE KNOWS OF AT LEAST A HALF DOZEN OTHER INCIDENTS OF NOSE STEERING PROBS.