On March 28, 1997, about 1645 central standard time, a Hughes TH-55 helicopter, N818D, registered to a private owner, crashed while maneuvering at a low altitude near Cullman, Alabama. Visual meteorological conditions prevailed at the time and no flight plan was filed for the Title 14 CFR Part 91 local instructional flight. The commercial-rated pilot/certified flight instructor (CFI) and student pilot received serious injuries. The helicopter was substantially damaged. The flight originated about 1 hour before the accident. The flight had remained in closed traffic at Folsom Field, in order for the pilots to perform practice maneuvers and emergency procedure training, to include autorotations. Witnesses saw the helicopter takeoff to the west, and turn immediately to the right, climb to an altitude of 30 feet above ground level (AGL), and attain an estimated forward airspeed of 20 to 30 knots. The helicopter was observed in an almost vertical descent, and disappear out of view of the witnesses, before they heard the sound of impact with the ground. One of the witnesses stated that just prior to impact, "...I heard what sounded like the helicopter doing a hovering autorotation, the engine sounded like it over speeded then cut...." Other witnesses also said they had heard what sounded like an overspeed before impact. According to investigators that were at the crash site, ground scars indicated that the helicopter impacted on heading of 040 degrees, with little to no forward movement. The helicopter landed near a telephone pole and support lines. There was no evidence found to indicate that the helicopter contacted the pole or the lines. The first people to arrive at the crash site said that both pilots were alive, and the student pilot said he did not know what had happened. The CFI said, "we had been flying for about an hour. We'd finished our training and were heading back with...[the student] on the controls, when the engine quit. I said I've got it and took the controls, but we were too low, with no time to recover, and crashed." According to the FAA inspector's statement, there was evidence found at the crash site "indicating low main and tail rotor RPM at impact," because the rotor blades showed little damage. In addition, the engine examination revealed no discrepancies. The FAA concluded that "the engine was running at impact." The helicopter examination revealed control continuity on all flight controls and no discrepancies were found with the helicopter. Several attempts were made to talk to the CFI at the hospital to get his factual account of the accident, but all attempts to interview him were unsuccessful. The NTSB Form 6120.1/2, was returned without a statement from the CFI.