N4171J

The certificated flight instructor (CFI) was providing primary helicopter flight instruction to a student pilot. The CFI reported that while practicing a series of hovering autorotations, he inadvertently allowed the student pilot to drift to the left during the descent. The CFI then took control of the helicopter, applied right cyclic and raised the collective slightly to level the helicopter and arrest the descent, but the helicopter started to descend with the right skid low. He then added left cyclic, and raised the collective further in an attempt to cushion the landing. The helicopter then drifted to the right as the right skid subsequently struck the ground. After touchdown, the helicopter’s skids slid over the asphalt surface before the right skid “caught” and the helicopter rolled to the right, and the main rotor blades struck the ground. The helicopter came to rest on its right side, sustaining substantial damage to the fuselage, tail boom and main rotor drive system. In his written statement to the NTSB, the pilot reported that there were no preaccident mechanical problems with the helicopter, and in the recommendations section of the NTSB 6120.1 form he reported that the accident might have been avoided if he had taken corrective action sooner, and with less input on the cyclic.