Narrative:

This event occurred on the last leg of a six leg day. Both the captain and first officer (myself) had been up for approximately 13 1/2 hours at that time. Several of the previous legs had 2 hour layovers. We had been cleared onto runway 31 for an immediate takeoff. The remaining checklist items were completed and the captain turned the aircraft over to me as we were taxiing onto the runway. As power was increased on the takeoff roll the aircraft lurched severely to the left. Power was decreased immediately and the brakes were applied by both myself and the captain. A steering microswitch lever was disengaged and by the combination of both brakes and alternate function steering the aircraft was brought to a stop onto a taxiway to the left and somewhat forward of where the aircraft had begun its takeoff roll. At this point we requested clearance for back taxi to the ramp so maintenance could attempt to determine the cause of the problem. Callback conversation with reporter revealed the following: the flight crew had been given a choice of an immediate takeoff or wait for aircraft on final to land and they chose to take it rolling. One propeller was still locked in flat pitch so thrust was not even and aircraft control was lost for a brief time. After return to blocks no problem could be found with aircraft and it redeparted after a maintenance walk around.

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Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.