20140922017309A

Weather was VMC with light to moderate headwinds for the runway. The flight was an instruction flight to prepare a commercial pilot for an additional flight instructor rating. The pilot and flight instructor were coming to the end of the flight period was near conclusion and the student had conducted a successful touchdown 180 degree autorotation previously. They briefed for next 180 degree autorotation and preceded to enter the maneuver at approximately 1000 feet AGL. The instructor noted coming out of the turn the student was 5 knots slow. The student lowered the nose to accelerate and lined up with the intended touchdown runway. The maneuver was described as normal until the flare. Flight instructor stated that the student's flare was a little more nose high than normal but should have be within normal given the winds. Both pilots then noticed a high sink rate. Both pilots heard a bang and only the flight instructor felt the impact. The aircraft leveled and landed skids level. The flight instructor stated that impact on the landing was not much harder than a normal landing. Both pilots felt a high frequency vibration and both looked back to the tail section. Neither pilot observed and damage but could see the tailboom vibrating laterally. The flight instructor initiated an emergency shutdown. Damage to the vertical stab, horizontal stab, tail boom and drive shaft subsequently ensued.