Medium Transport; High Wing; 2 Turboprop Eng
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 120; Flight Crew Total 10000; Flight Crew Type 4000
Human-Machine Interface; Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Loss Of Aircraft Control; Ground Incursion Taxiway
General None Reported / Taken
Airport; Procedure
The aircraft was sitting on a non-movement taxiway 150 feet clear of an active taxiway with the parking brake engaged.  The pavement was bare with patches of compacted snow.  An engine run-up was initiated.  The crew checked to see if the aircraft was holding traction.  Once the crew was convinced that the aircraft was not moving a test procedure was initiated.  During the procedure the aircraft lost traction with the pavement and began to slide.  Power was reduced and full propeller reverse was used.  The aircraft slid on to an active taxiway before it could be completely stopped.  The power reduction was delayed due to inadvertent power lever trigger actuation which caused the power levers to be locked in position until the triggers were released.  This caused a delay in power reduction and reverse initiation.
A turboprop Captain; performing an engine run-up test procedure in a non-movement area of the airport noted the aircraft was sliding on the snow and ice encrusted runway.  Before he was able to disengage the power lever trigger to allow throttle movement the aircraft had slid onto an active taxiway.