On October 12, 1996, at 1900 eastern daylight time, a Bell UH-1B, N846MC, collided with the ground and a stump under unknown circumstances near Bennettsville, South Carolina. The aerial application flight operated under the provisions of Title 14 CFR Part 137, with no flight plan filed. Visual weather conditions prevailed at the time of the accident. The helicopter was destroyed, and the pilot received serious injuries. The flight departed the staging area in Bennettsville, South Carolina, at 1847. According to the operator, the pilot sustained head injuries and, is still unable to give an account of the accident. The operator's records showed that the flight departed the staging area about 1847. The purpose of this flight was to complete the spraying operation that had been started earlier. The operator also stated that the ground personnel, who assisted the pilot in the loading and refueling operation, did not witness the events of the accident; there were no reported eyewitnesses to the accident. Examination of the accident site disclosed that the tail section of the airframe collided with the ground, followed by the nose section collision with a stump. The helicopter rested on the right side with the nose section orientated in the opposite direction of the initial flight path. During the examination of the wreckage, a small quantity of fuel was recovered from the fuel system. The subsequent examination of the airframe and subsystems failed to disclose a mechanical problem. However, a review of the aircraft maintenance logs revealed several open discrepancies. One discrepancy stated that the left fuel boost pump was not operational. According to the aircraft operator's manual approximately 55 pounds of fuel would be unusable in the left tank when the boost pump is not operational. The wreckage examination also revealed that the right fuel tank had approximately 1/4 inch of fuel at the lowest point. There were about four inches or less than 55 pounds of fuel in the left fuel tank at the lowest point. The odor of fuel or visible fuel leakage was not observed at the accident site. The cockpit examination revealed that the left fuel pump boost circuit breaker was out. There is no fuel tank selector installed on the UH-1B helicopter.