On April 27, 1994, at 1015 central daylight time, a Bell 47G helicopter, N46DH, operated as a training aircraft by C. R. Hill of Springfield, Missouri, impacted the ground during a practice autorotation at Air Park South, Springfield, Missouri, and was substantially damaged. The Designated Pilot Examiner/flight instructor and flight instructor student were not injured. Visual meteorological conditions existed at the time of the accident and no flight plan was filed. The flight was operated under 14 CFR Part 91 as a flight instructor training flight. The practice autorotation was initiated during a practice low level agricultural application turn. According to the pilot, collective input to cushion the landing was made too early, main rotor rpm decayed and the helicopter landed with a high descent rate. Upon touchdown, the helicopter bounced and pitched nose down. The pilot in command reported that the combined aft cyclic input by both pilots and blade flexing resulted in rotor blade to fuselage contact, severing the tail boom.