On June 21, 2001, at 1440 mountain standard time, a Schweizer 269C, N891CP, landed hard on the helipad at Falcon Field Airport (FFZ), Mesa, Arizona, following a loss of engine power. The helicopter, operated under the provisions of 14 CFR Part 91, sustained substantial damage to the tail boom. The certified flight instructor (CFI) and student pilot were not injured. Visual meteorological conditions prevailed for the local area instructional flight, and a flight plan had not been filed. The flight departed FFZ at 1330, and was scheduled to terminate at FFZ. According to the CFI, the purpose of the flight was to conduct pattern work and approaches to landing. About 1430, while on approach to land, at 200 feet agl and an airspeed below 50 knots, the CFI heard a "pop" from the engine. He saw the engine rpm dropping to zero and he entered an autorotation. The helicopter landed hard. A Federal Aviation Administration (FAA) inspector interviewed the CFI. The CFI stated that he was demonstrating a normal approach for the landing. When he heard the engine "pop," he attempted to add throttle. During the autorotation, the tachometer needles split and the helicopter landed hard. The FAA inspector noted that the CFI entered the autorotation inside the height velocity envelope curve. The FAA inspector reported that the result was a high rate of descent at touchdown. According to the height/velocity performance chart in the rotorcraft flight manual, at 200 feet agl the helicopter had to be above a speed of 50 knots in order to accomplish a successful autorotation. The FAA inspector observed a successful post accident engine test run and noted no mechanical anomalies. METEROLOGICAL CONDITIONS Phoenix Sky Harbor International Airport (PHX), elevation 1,135 feet msl, is about 255 degrees at 16 nautical miles from the accident location. The aviation surface weather report at 1356, was winds from 290 degrees at 14 knots; visibility 10 miles, temperature 100 degrees Fahrenheit; dew point 55 degrees Fahrenheit; and altimeter setting 29.94 inHg. The sky condition was few clouds at 12,000, and scattered cloud layers at 18,000 and 25,000. In the pilot's written statement to the Safety Board he indicated that the temperature at FFZ was 115 degrees Fahrenheit. According to a density altitude calculator utilized by the Safety Board, at the time of the accident the density altitude was 5,390 feet mean sea level (msl). The airport elevation is 1,394 msl.