Sa-227 metro III captain reported rejected takeoff due to loss of torque on one engine resulting in ...

Narrative:

When attempting to set takeoff power the left engine did not produce more than 25-30% torque. After verifying that this was not due to a momentary lag of torque; which I have experienced on many metro engines/takeoffs; the takeoff was aborted however the plane was heading to the left of center line due to the higher torque achieved by the right engine. When the power levers were brought to idle the plane straightened down the runway to the left of the center line. The nose wheel steering button on the power lever was being pushed but either it was not working or was not effective enough to turn the plane back toward the center line. I verified with my left thumb and finger that the nose wheel steering switch was in the armed position and also pressed the 'park' steering function for additional turning help. When I (quickly) recognized that wasn't working left power was applied with the hope that there would be some power and right brake was applied to try to turn the plane to the right however; it didn't work and instead the plane started turning to the left and exited the runway where the plane stopped and was shutdown. After shutdown it was observed that a left propeller tip hit a runway edge light.

Original NASA ASRS Text

Title: SA-227 Metro III Captain reported rejected takeoff due to loss of torque on one engine resulting in a loss of directional control; and a runway excursion.

Narrative: When attempting to set takeoff power the left engine did not produce more than 25-30% torque. After verifying that this was not due to a momentary lag of torque; which I have experienced on many Metro engines/takeoffs; the takeoff was aborted however the plane was heading to the left of center line due to the higher torque achieved by the right engine. When the power levers were brought to idle the plane straightened down the runway to the left of the center line. The nose wheel steering button on the power lever was being pushed but either it was not working or was not effective enough to turn the plane back toward the center line. I verified with my left thumb and finger that the nose wheel steering switch was in the armed position and also pressed the 'park' steering function for additional turning help. When I (quickly) recognized that wasn't working left power was applied with the hope that there would be some power and right brake was applied to try to turn the plane to the right however; it didn't work and instead the plane started turning to the left and exited the runway where the plane stopped and was shutdown. After shutdown it was observed that a left propeller tip hit a runway edge light.

Data retrieved from NASA's ASRS site 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.

Attributes
ACN	1654469
Time
Date	201906
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	SA-227 AC Metro III
Operating Under FAR Part	Part 121
Flight Phase	Takeoff
Flight Plan	IFR
Component
Aircraft Component	Engine
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy Ground Event / Encounter Ground Strike - Aircraft Ground Event / Encounter Loss Of Aircraft Control Ground Excursion Runway

Sa-227 metro III captain reported rejected takeoff due to loss of torque on one engine resulting in a loss of directional control; and a runway excursion.