On September 7, 2003, at 1400 mountain daylight time, a Cessna 182A, N6384B, was substantially damaged when it impacted terrain during a forced landing near Pine Haven, Wyoming. The airline transport pilot, the sole occupant on board, was not injured. Visual meteorological conditions prevailed. No flight plan had been filed for this local flight being conducted under Title 14 CFR Part 91. The flight originated at 1335 from a private airstrip near Pine Haven. According to the pilot, he completed an air drop of skydivers and was returning to land on runway 18. During the final approach, he added power to maintain altitude and obstacle clearance, and the engine "quit without sputter[ing]." He made a forced landing in a sagebrush covered field. The airplane struck the ground, slid down a gully, and nosed down as it struck a tree. The impact separated the airplane's nose landing gear, displaced the engine and engine mount, and buckled the aft fuselage and firewall. The pilot stated that after pulling the airplane from the gully, he visually checked the fuel and stated that there were 10 gallons of fuel in each wing tank. He also stated that he "did not know the cause of the engine failure." At 1355, the reported weather at Gillette-Campbell County Airport (GCC), Gillette, Wyoming (approximately 32 nautical miles west of the accident site, and at an elevation of 4,363 feel msl) was: wind, 230 degrees at 15 knots, gusting to 19 knots; visibility, 10 statute miles; sky condition, few at 10,000 feet; temperature, 31 degrees C.; dew point, 7 degrees C.; altimeter setting, 30.01. The calculated density altitude was 7,204 feet msl.