The operator reported that prior to the accident flight, the pilot was distracted during his intended refueling operation. The distraction involved ground personnel entering the helicopter cabin after landing to discuss the next spraying operation with the pilot. After the conversation, the pilot departed without refueling the helicopter. While completing an aerial application, the engine experienced a loss of engine power. The pilot initiated an autorotation and impacted terrain. A postaccident examination of the helicopter showed the tail boom was partially separated and the landing gear skids were bent. The operator reported that approximately 3.5 quarts of fuel were drained from the fuel tanks, and 2 gallons of fuel were considered unusable.