On July 5, 2007, about 0800 central daylight time, N500NC, registered as Hughes 369D helicopter, piloted by a commercial pilot, sustained substantial damage on impact with terrain during a forced landing following a loss of engine power during an aerial application spray run near Comfrey, Minnesota. The local aerial application flight was operating under 14 CFR Part 137. No flight plan was on file. Visual meteorological conditions prevailed at the time of the accident. The pilot, the sole occupant, reported no injuries. The origin and destination of the flight are unknown. The pilot's accident report, in part, stated: On the second pass of the second load, and in the middle of the field headed west, the engine began to spool down in RPM. I heard the engine sound of lost RPM, at that time my eyes were on the wires that the aircraft was approaching, N2 Rotor was at or about the bottom Red Line. My choices were to attempt to auto rotate across the wires, the road, and the people to the field beyond. At that split second I decided to attempt the grass area south of the field. Low N2 and air speed (about 75 mph), lowered collective attempted a 180 [degree] auto rotation, the engine and rotor seemed to speed up or surge. I attempted to do the auto as best as I could. Was able to land square on the skids, but the helicopter still bounced. The landing gear spread hitting the tanks, and snapping the uprights above the tanks. At that point, forward leg stuck in the ground, making the helicopter pitch forward. The blade in front made contact with the ground. The rotor system came around cutting the boom faring and tail off. Federal Aviation Administration Inspectors examined the wreckage. The pressure line which connected to the Pg boss on the fuel control was found finger tight.