On November 1, 2003, at 0752 mountain standard time, a Fairchild Swearingen SA227BC, N787KL, operated by Key Lime Air, was substantially damaged after striking a snow bank while landing at Rawlins Municipal Airport (RWL), Rawlins, Wyoming. The commercial pilot, the sole occupant on board, was not injured. Instrument meteorological conditions prevailed. The non-scheduled domestic cargo flight was being conducted under the provisions of Title 14 CFR Part 135. An IFR flight plan had been filed for the flight that originated from Denver International Airport, Denver, Colorado, at approximately 0640. According to the accident report submitted by the pilot, he was circling to land on runway 22 after executing the NDB-A approach. During the circling approach, the pilot noted that the runway was snow covered. During the landing roll, the airplane began to slide to the left. The pilot applied right rudder and reversed the right propeller. The airplane slid for approximately 1,900 feet and went off the left side of the runway. The airplane struck a snow bank, wrinkling and bending the airplane's nose section. An examination of the airplane's systems revealed no anomalies.