The 1,425-hour helicopter rated flight instructor and a 130-hour private helicopter pilot lifted-off in the piston-engine powered helicopter for a local instructional flight. The flight instructor planned to demonstrate "a hovering autorotation with forward speed." The instructor reported that "after initiating the maneuver, [he] failed to level the aircraft, [and] as the aircraft descended ... the toes of the landing skids contacted the ground." The helicopter continued rotating forward until the main rotor blades impacted the ground. As the helicopter rocked back, the main rotor blades then struck the tail-rotor driveshaft. In the Recommendation section of the NTSB Form 6120.1 (How could this accident have been prevented ?), the flight instructor stated that the accident could have been prevented if "the aircraft had no forward speed", "if aircraft touched down in a level attitude, or if the maneuver had been performed over a hard surface."