Falcon 20FJF/20C/20D/20E/20F
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 140; Flight Crew Total 11300; Flight Crew Type 600
Aircraft Equipment Problem Less Severe; Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Taxiway
Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification
Aircraft; Weather
After a normal landing and deceleration on Runway XXR at ZZZ I applied normal braking and below 80 kts applied nosewheel steering both of which operated normally. Tower advise us to make a left turn on Taxiway XX; back taxi Runway XXL and take Taxiway XY to the ramp. (Note: All Taxiways and Runways were dry and free of contamination at the time) Turning onto Taxiway XY required an approximate 120 turn to the left to join. At this point the nose wheel steering was operating normally. After the turn the aircraft started drifting to the left; I tried correcting this with opposite nose wheel steering with no effect. I immediately tried to apply maximum braking to stop all aircraft movement with no braking action resulting; by the time I was going to apply Number 2 braking we were in the grass and stopped. We shut down the engines and we called the Tower to advise them of our situation on Taxiway XX. The Tower acknowledged our call and advised us someone from [company] would be coming to assist us. I exited the aircraft to check for any damage to the aircraft and any airport infrastructure; lights; signage; etc. and there was none. I called the Chief Pilot to inform him of the incident. The [company] representative arranged for a Tug and tow bar to assist us. The temperatures had been in the twenties so the ground was firm and the plane was returned without incident [company] coordinated the tow with the Tower for towing clearances and the plane was towed to the ramp without any incident. Maintenance was called by the Company and secured the aircraft.
Falcon 20 Captain reported a problem with their nose wheel steering and ended up going off the taxiway into the grass.