SA-227 AC Metro III
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Commercial
Flight Crew Last 90 Days 130; Flight Crew Total 875; Flight Crew Type 660
Aircraft Equipment Problem Critical; Ground Event / Encounter Ground Strike - Aircraft; Ground Excursion Taxiway; Inflight Event / Encounter Loss Of Aircraft Control
Aircraft Aircraft Damaged; Flight Crew Regained Aircraft Control; Flight Crew Returned To Gate; General Flight Cancelled / Delayed; General Maintenance Action
Airport; Human Factors
Weather conditions were VFR; visibility was 10 miles clear below 12;000 and winds were 290 at 6 KTS. After start up and initial checklists were completed we announced on CTAF that we were going to taxi to Runway 2 via A and C. We made a left on A and then a right on C on our way to the runway.  About 10 seconds later; during the Nose Wheel Steering Test; the aircraft began to veer to the right and went off centerline. The Captain applied maximum braking; reverse thrust and left rudder in order to bring the aircraft under control. While doing so the right propeller struck one taxi light. After regaining control of the aircraft we made a 180 degree turn and proceeded to taxi back to the FBO via C and A.After engine shutdown we contacted our Chief Pilot who then advised the Airport Manager about the situation. An inspection revealed there was damage on one of the four propeller blades and the flight was cancelled.
The right main wheels left the taxiway. As the aircraft started its return to the taxiway; I saw what was best described as a puff of smoke in the copilot's side window. I decided to return to the ramp.During [the taxi back] I saw no abnormal engine indications or felt any unusual vibrations. As I taxied back to the ramp; I checked the western edge of Taxiway C and saw a taxiway light was missing.
An SA227 flight crew lost control of the aircraft during a control check during taxi for takeoff; exited the taxiway and struck a runway light with one blade of the right propeller.