Date: 201911
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Super King Air 300
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
Aircraft component: Engine Control
Component problem: Malfunctioning
Reporter organization: Corporate
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Engineer; Flight Crew Flight Instructor; Flight Crew Instrument
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Returned To Gate; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: I fly a King Air 350/G1000 part time and an unusual event occurred that I think should be studied by the appropriate authority. I don't know another way to put this out there.While [we] were taxiing for takeoff; the rudder pedals seemed a bit too stiff and it was causing the aircraft to pull slightly to the right but that was overshadowed by another potential issue that was noted at the same time...the right torque indication was frozen at a fixed value of about 47%. We pulled off to the run-up area and after a discussion with the other pilot; we decided the aircraft was unairworthy since we could not determine the cause of the torque problem. Little discussion took place about the pedals/pulling since the torque reading was so clearly an issue.We turned the aircraft over to Maintenance and reported the two issues. The mechanics focused immediately on the torque indication and almost seemed uninterested in the steering issue. They had just changed brake lines as part of a scheduled event; and the tire pressure was a bit low; so we left the aircraft with them thinking they had a logical explanation; and the two issues were unrelated.Upon digging into the torque reading error they determined that deep within the engine the torque sensing oil line was likely clogged and after several maintenance procedures the problem went away; and the aircraft went back into service after a successful test flight. I did not hear a definitive cause; just speculation.In hindsight; to this pilot; it seems as though the bad torque reading triggered the activation of the rudder boost system; but due to the minimal force applied and the focus on the torque indication; I can see the potential for a life threatening problem for unsuspecting pilots if this were to occur at the wrong time or not handled properly. It might have been tempting to fly with a bad torque reading and not detect the rudder boost problem until it's too late. I don't have an MEL (Minimum Equipment List) available to me as I write this; but [I] assume that to some pilots the temptation/pressure to fly with just an 'indication' problem might lead to an accident.It has me thinking about two recent King Air crashes that I read about and I feel it's my responsibility to bring this to someone's attention just in case there might be an insidious safety problem.




Synopsis: BE-300 flight crew reported encountering an engine torque problem during taxi for takeoff.