On February 20, 2006, approximately 1845 mountain standard time, a Swearingen SA226TC, N235BA, piloted by a commercial pilot and operating as Spendair Flight 1713, sustained minor damage when the airplane's left propeller struck a runway marker light, following a loss of directional control during takeoff from the Natrona County International Airport (CPR), Casper, Wyoming. Night visual meteorological conditions prevailed at the time of the incident. The non-scheduled, domestic passenger flight was operating on an instrument flight rules flight plan from CPR to Denver, Colorado, under the provisions of Title 14 CFR Part 121. The pilot and two passengers on board were not injured. The flight was originating at the time of the incident. According to the pilot, he had set engine power to 60 percent rpm for takeoff, released the brakes, and the airplane steered straight ahead. At approximately 800 feet down runway 21 (10,600 feet by 150 feet, dry asphalt), the airplane veered to the right. The pilot said he applied full left steering (tiller) and full left rudder, but the airplane continued to veer right. The pilot said he then used full reverse propeller to arrest the forward motion. The airplane went off the right edge of runway 21 and stopped approximately 1,300 feet from the start of the takeoff roll. A preliminary examination of the airplane showed the nose wheel was turned beyond the right turn limit mark. The left propeller sustained damage to all 4 blade tips. At 1853, the Aviation routine Weather Report at CPR was clear skies, 10 miles visibility, temperature 18 degrees Fahrenheit (F), dew point 7 degrees F, and altimeter 29.87 inches. Further examination of the nose wheel steering system failed to show why the airplane initiated the uncontrolled turn. All other systems showed no anomalies.