On August 18, 1993, at about 1100 eastern daylight time, a Schweizer 269C, N95AF, registered to Helicopter Training Academy Inc., operating as a 14 CFR Part 91 instructional flight, crashed while the commercial pilot/flight instructor was demonstrating an autorotation with turn to the private pilot receiving instruction. The helicopter sustained substantial damage. Neither flight crewmember were injured. Visual meteorological conditions prevailed and no flight plan was filed. The flight originated from Punta Gorda Airport about 20 minutes before the accident. The flight instructor stated to the NTSB investigator-in-charge, that he conducted a flare at 50 feet agl and applied initial collective pitch at 15 to 20 feet agl, when he heard a noise described as a pop. Both crewmembers were concentrating on the noise, when the tail skid and tail rotor blades collided with the terrain as he was applying cushioning collective pitch to terminate the autorotation at a hover. The helicopter began to spin to the right. Left antitorque pedal was applied and the throttle was rolled off to the engine idle stop. The helicopter came to a complete stop upright on the skids. Examination of the helicopter by an authorized repair station revealed all damage was a result of impact with the terrain. There was no evidence of any precrash failure or malfunction of the tailrotor gear box or associated components.