Accident Sequence
A Certified Flight Instructor (CFI) and a student pilot were conducting practice landings and autorotations at an airport. After completing several maneuvers, they departed for a practice area. The CFI demonstrated straight-in autorotations and 180-degree autorotations. The first 180-degree attempt was initiated at 6,000 feet mean sea level with an airspeed of 55-60 knots. During the second 180-degree attempt, the maneuver began approximately 200 feet lower. As the helicopter turned, airspeed decreased to about 50 knots, and the main rotor blades' revolutions per minute (rpm) began to decay rapidly.
At about 200 feet above ground level, the CFI attempted a power recovery by increasing throttle, but the rotor rpm did not increase. He then attempted to flare to restore rpm, but this was also unsuccessful. Subsequently, he initiated a full-down autorotation and positioned the helicopter in a level attitude before ground contact.
Impact and Damage
The helicopter contacted the ground and bounced. On the second impact, the right skid dug into muddy terrain, causing the helicopter to roll onto its right side. Both pilots were not injured and extricated themselves from the wreckage. The helicopter sustained substantial damage to the airframe and rotor blades.
Pilot Statements
The pilots reported that the helicopter experienced no mechanical failures or malfunctions during the accident sequence.