PC-12
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine; Other TYPE C500 series
Flight Crew Last 90 Days 150; Flight Crew Total 3000; Flight Crew Type 1000
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Object; Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Taxiway
Air Traffic Control Provided Assistance; Flight Crew Overcame Equipment Problem; Flight Crew Returned To Gate; Flight Crew Regained Aircraft Control; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft
Began taxi to Runway XX for north departure to ZZZ1.  EMS flight with patient on board.  Applied power and after plane taxied approx 10-15 feet an uncommanded right wheel hard stop occurred which caused a sharp 90 degree turn.  The nose wheel hit a snow bank and the right wing hit a fence post.  Reverse power was applied to move plane back onto taxiway.  No injuries.  Pilot determined that [the] plane was not airworthy and shut down.  Company was contacted. Pilot/airport observers/med crew all concurred that it appeared the right brake was stuck or something impeded the movement of the right tire.  There was no FOD; ice; or snow on the ramp - dry clear pavement.  Wind was 020 at 7 with no gust factor.  Unlimited ceilings and unlimited visibility. OAT 45F. Company contacted FAA and pilot was sent for a DOT post accident [incident] screen. Pilot removed from line duty until results of DOT screen are obtained.  Event occurred at approximately XA:00 on date.  A mechanic was dispatched but then company informed pilot to move plane back off taxiway as no mechanic would be coming that night after all.  Pilot reviewed event in detail and determined that nothing was non-standard as far as flows/checklists/standard procedures regarding start and taxi.
Pilot reported on taxi for departure; the aircraft swerved to the right; becoming uncontrollable.