FLT CREW LOST CTL OF COMMUTER SMT AT THE START OF TKOF.

Narrative

THIS EVENT OCCURRED ON THE LAST LEG OF A SIX LEG DAY. BOTH THE CAPT AND F/O (MYSELF) HAD BEEN UP FOR APPROX 13 1/2 HOURS AT THAT TIME. SEVERAL OF THE PREVIOUS LEGS HAD 2 HOUR LAYOVERS. WE HAD BEEN CLRED ONTO RWY 31 FOR AN IMMEDIATE TAKEOFF. THE REMAINING CHECKLIST ITEMS WERE COMPLETED AND THE CAPT TURNED THE ACFT OVER TO ME AS WE WERE TAXIING ONTO THE RWY. AS POWER WAS INCREASED ON THE TKOF ROLL THE ACFT LURCHED SEVERELY TO THE L. POWER WAS DECREASED IMMEDIATELY AND THE BRAKES WERE APPLIED BY BOTH MYSELF AND THE CAPT. A STEERING MICROSWITCH LEVER WAS DISENGAGED AND BY THE COMBINATION OF BOTH BRAKES AND ALTERNATE FUNCTION STEERING THE ACFT WAS BROUGHT TO A STOP ONTO A TAXIWAY TO THE L AND SOMEWHAT FORWARD OF WHERE THE ACFT HAD BEGUN ITS TKOF ROLL. AT THIS POINT WE REQUESTED CLRNC FOR BACK TAXI TO THE RAMP SO MAINT COULD ATTEMPT TO DETERMINE THE CAUSE OF THE PROBLEM. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: THE FLT CREW HAD BEEN GIVEN A CHOICE OF AN IMMEDIATE TKOF OR WAIT FOR ACFT ON FINAL TO LAND AND THEY CHOSE TO TAKE IT ROLLING. ONE PROP WAS STILL LOCKED IN FLAT PITCH SO THRUST WAS NOT EVEN AND ACFT CTL WAS LOST FOR A BRIEF TIME. AFTER RETURN TO BLOCKS NO PROBLEM COULD BE FOUND WITH ACFT AND IT REDEPARTED AFTER A MAINT WALK AROUND.