19981210044229A

(.19)On December 10, 1998, at 1400 eastern standard time, a Robinson R-22, helicopter, N2321X, collided with the ground, according to the flight instructor, during a practice autorotation, at the lantana airport, in lantana, Florida. The instructional flight operated under the provisions of title 14 CFR part 91 with no flight plan filed. A review of weather data from the nearest reporting facility revealed that, visual weather conditions prevailed at the time of the accident. According to the director of maintenance for the operator, the helicopter sustained substantial structural damage to the airframe. The flight instructor and the dual student were not injured. The initial departure time of the flight from lantana, Florida, was not determined. The flight instructor reported that he and the dual student were conducting autorotation training. The dual student had completed several power recovery autorotations, and the session had progressed to the point where the dual student was ready for a 180-degree autorotation. The flight instuctor was demonstrating a 180-degree autorotation, with power recovery, when the accident occurred. The flight instructor stated that he did no t believe that the engine responded when the power was applied for the recovery. (.4) the flight instructor was demonstrating a 180-degree autorotation, with power recovery, when the accident occurred. As the helicopter descended through 200 feet the low rotor RPM horn sounded. The tachometer was at about 92 percent. The flight instructor then rolled on the throttle and went down on the collective simultaneously. The helicopter contacted the ground in a level attitude. The instructor attempted a shallow flare, and cushioned with collective. The aircraft slid in grass, the right skid dug into the ground and the helicopter rolled over. No mechanical problems with the airplane were discovered during the wreckage examination.