On October 21, 1999, at 1410 central daylight time, a Robinson R22 Beta helicopter, N2301C, was substantially damaged during a hard landing at the Jonesboro Municipal Airport, near Jonesboro, Arkansas. The helicopter was registered to Summit Properties LLC, of Bryant, Arkansas, and operated by Bonham Helicopters Inc., of Harrisburg, Arkansas. The flight instructor and the helicopter-rated student were not injured. Visual meteorological conditions prevailed for the 14 Code of Federal Regulations Part 91 instructional flight, and a flight plan was not filed. The local flight originated from the Jonesboro Municipal Airport, at 1310. According to the flight instructor and the student, after a one hour break from a previous flight, they initiated a second flight to practice additional maneuvers, including autorotations. About one hour into the second flight, the student performed a takeoff, and at 500 feet agl, the flight instructor "initiated a throttle roll-off." The student then entered an autorotation straight ahead, during which time the flight instructor was "riding the controls." The flight instructor stated that they planned on a power recovery. Approximately 250 feet agl, the low rotor horn sounded, and the low rotor light illuminated. The flight instructor reported that the student decreased the collective, but "it was too small of an amount too late." The flight instructor then initiated a go-around and "released back pressure on the cyclic, decreased the collective and rolled the throttle on, but the engine did not respond. The engine needle remained at idle." The helicopter was descending through 75 feet agl when the flight instructor "lowered the collective and initiated a hard flare." However, there "was not enough energy transferred to the main rotor blade to cushion the touchdown." The helicopter impacted the ground, and the main rotor blades contacted and severed the tail boom. The operator reported that the aft section of the tail boom and tail rotor drive shaft separated from the airframe. Additionally, the cabin doors separated from the airframe and the skids were spread. On November 17, 1999, the engine was placed in a test stand and operated at the Robinson Helicopter Company, Torrance, California, under the supervision of an FAA inspector. The engine was started and operated for a total of 41 minutes at various power settings, including maximum power (2700 rpm) and idle. The engine operated within the manufacturer's specifications. No fuel or oil leaks were noted.