HISTORY OF FLIGHT: On July 18, 1993, 1630 CDT, while operation under FAR part 137 a helicopter, Hiller, N4028M, Model UH-12E registered to Bonanza Valley Aviation, Inc. of Bensen, MN and piloted by Richard Harrison Jackson of Bensen, MN, lost directional control and struck nearby hay bales. The helicopter continued to rotate and contacted the ground, it became airborne again and impacted into a cluster of hay bales. INJURIES TO PERSONS: The pilot received cuts, bruises and a sprained ankle. DAMAGE TO AIRCRAFT: The helicopter was destroyed. OTHER DAMAGE: Several large round hay bales sustained damage. CREW INFORMATION: The pilot was the sole occupant. Pilots name is Richard Harrison Jackson. Pilots address is 1720 MN Ave., Benson 56215. He is 40 years old. The pilot possessed a valid Commercial Pilot Certificate, Helicopter Rating, current Second Class Medical Certificate, and current Biennial Flight Review. AIRCRAFT INFORMATION: Aircraft was a Hiller, Model UH-12E, Serial Number 5094 registered to Bonanza Valley Aviation, Inc., Box 24, Benson, MN 56215. The last 100 hr inspection was 7-2-93. METEOROLOGICAL INFORMATION: Visual Meteorological conditions prevailed. WRECKAGE: Wreckage was so severe that a malfunction or failure (if any) could not be determined. FIRE: A fire started immediately after aircraft came to rest consuming the aircraft and adjacent hay bales. The fire was fueled by aviation gasoline from the helicopters ruptured fuel tank and hay.