The helicopter flight instructor reported that during a local instructional flight, he was demonstrating a 180 degree autorotation to the ground. The flight instructor reported he entered the autorotation and everything was normal. During the flare, too much aft cyclic input was used and the helicopter touched down on the heels of the skids. The flight instructor reported the touchdown was not excessively hard or uneven. A post flight examination of the helicopter revealed that the main rotor blade had contacted the tail boom, causing substantial damage to the tail boom.

The flight instructor reported that there were no preimpact mechanical failures or malfunctions with the helicopter that would have precluded normal operation.