Narrative:

We taxied into takeoff position on runway 22 and completed appropriate checklists (the speed levers were advanced to 100 percent). When the captain advanced the power levers to flight idle from the beta (reverse) range, the aircraft pulled abruptly to the right and began sliding toward the side of the runway at a 45 degree angle. He immediately recognized that the left hand engine was producing torque while the right hand engine was not. He applied full reverse to both engines along with left brake and nose wheel steering. Despite our efforts, the aircraft continued sliding off the runway into the snow. The traction produced by the snow aligned the aircraft with the runway. He continued correcting until we were once again on the runway surface. We thought that we may have struck a runway light, so we shut down the left engine as a safety precaution. We returned to the gate and deplaned the passengers. Post-flight inspection revealed damage to the left propeller blades. Appropriate company personnel were informed, as well the airport manager. Cause: the right engine start locks did not release when the engines were advanced to flight idel. The asymmetrical power condition caused the aircraft to depart the runway. Propeller damage caused by the left propeller striking a runway light. Contributing factor: the runway had 1/2' snow covering ice on that section of the runway. Recovery from the situation was extremely difficult due to the degraded control caused by the icy surface. Human performance: crew well rested and alert. The captain recognized and reacted to the situation quickly and correctly. Callback conversation with reporter revealed the following information. Braking action had been reported as fair but the actual conditions as a result of a light snowfall were poor. Center portion of the runway had been sanded. General discussion as to how the turbo propeller system works. In this case the 'beta' system which prevents adding takeoff thrust until both engines are in the forward thrust range failed to unlock and once the aircraft began to slide there was no stopping it. The engine was changed as a precaution.

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Original NASA ASRS Text

Title: APPLICATION OF TKOF THRUST RIGHT ENGINE FAILED TO ACCELERATE AT SAME RATE AS LEFT RESULTING IN RWY EXCURSION.

Narrative: WE TAXIED INTO TKOF POS ON RWY 22 AND COMPLETED APPROPRIATE CHKLISTS (THE SPD LEVERS WERE ADVANCED TO 100 PERCENT). WHEN THE CAPT ADVANCED THE PWR LEVERS TO FLT IDLE FROM THE BETA (REVERSE) RANGE, THE ACFT PULLED ABRUPTLY TO THE R AND BEGAN SLIDING TOWARD THE SIDE OF THE RWY AT A 45 DEG ANGLE. HE IMMEDIATELY RECOGNIZED THAT THE L HAND ENG WAS PRODUCING TORQUE WHILE THE R HAND ENG WAS NOT. HE APPLIED FULL REVERSE TO BOTH ENGS ALONG WITH L BRAKE AND NOSE WHEEL STEERING. DESPITE OUR EFFORTS, THE ACFT CONTINUED SLIDING OFF THE RWY INTO THE SNOW. THE TRACTION PRODUCED BY THE SNOW ALIGNED THE ACFT WITH THE RWY. HE CONTINUED CORRECTING UNTIL WE WERE ONCE AGAIN ON THE RWY SURFACE. WE THOUGHT THAT WE MAY HAVE STRUCK A RWY LIGHT, SO WE SHUT DOWN THE L ENG AS A SAFETY PRECAUTION. WE RETURNED TO THE GATE AND DEPLANED THE PAXS. POST-FLT INSPECTION REVEALED DAMAGE TO THE L PROP BLADES. APPROPRIATE COMPANY PERSONNEL WERE INFORMED, AS WELL THE ARPT MGR. CAUSE: THE R ENG START LOCKS DID NOT RELEASE WHEN THE ENGS WERE ADVANCED TO FLT IDEL. THE ASYMMETRICAL PWR CONDITION CAUSED THE ACFT TO DEPART THE RWY. PROP DAMAGE CAUSED BY THE L PROP STRIKING A RWY LIGHT. CONTRIBUTING FACTOR: THE RWY HAD 1/2' SNOW COVERING ICE ON THAT SECTION OF THE RWY. RECOVERY FROM THE SITUATION WAS EXTREMELY DIFFICULT DUE TO THE DEGRADED CTL CAUSED BY THE ICY SURFACE. HUMAN PERFORMANCE: CREW WELL RESTED AND ALERT. THE CAPT RECOGNIZED AND REACTED TO THE SITUATION QUICKLY AND CORRECTLY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. BRAKING ACTION HAD BEEN RPTED AS FAIR BUT THE ACTUAL CONDITIONS AS A RESULT OF A LIGHT SNOWFALL WERE POOR. CTR PORTION OF THE RWY HAD BEEN SANDED. GENERAL DISCUSSION AS TO HOW THE TURBO PROP SYS WORKS. IN THIS CASE THE 'BETA' SYS WHICH PREVENTS ADDING TKOF THRUST UNTIL BOTH ENGS ARE IN THE FORWARD THRUST RANGE FAILED TO UNLOCK AND ONCE THE ACFT BEGAN TO SLIDE THERE WAS NO STOPPING IT. THE ENG WAS CHANGED AS A PRECAUTION.

Data retrieved from NASA's ASRS site as of July 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.