N41TH

On May 20, 1998, at 1730 central daylight time, a Schweizer 269C helicopter, N41TH, registered to Equi-Sky, Inc., and operated by Travland Helicopters, was substantially damaged during an autorotational landing near San Angelo, Texas. The flight instructor and his passenger were not injured. Visual meteorological conditions prevailed, and a flight plan was not filed for the Title 14 CFR Part 91 personal flight. The flight originated from Mathis Field Airport, San Angelo, Texas, about 1700.

The pilot reported that he was demonstrating an autorotation to the passenger. He further reported that during the "simulated autorotation" to an open field, and upon completing a flare, "I leveled the helicopter to what would approximate a hover and added max allowable power to initiate a power recovery with the intention of a go around." After applying power, directional control was lost and the helicopter landed hard with a slight yaw.

The passenger reported that the pilot stated "he was going to demonstrate an autorotation so that I would understand how safe the helicopter is even without power." At the intended area for the demonstration, the pilot "retarded the throttle to idle." During the autorotation the pilot stated that "the spot we would land was visible basically right above the pedals." During the autorotational glide "directional control was stable." The nose of the aircraft raised "slightly" during the flare, which slowed the rate of descent "quickly." During the flare the helicopter turned clockwise. The aircraft "touched down approximately 90 degrees from the direction we were headed prior the flare." The landing seemed "firm" but not hard enough to be jarring. "Everything seemed to be under control." He did not remember the "engine accelerating at any time during the maneuver nor did he notice any unusual vibration." The pilot immediately shut down the engine and got out of the helicopter in a hurry. The passenger further reported that when he asked the pilot what happened, he remarked that "as he pulled collective and applied the pedals to compensate for the torque, that something seemed to give and the anti-torque pedal went to [the] floor." The passenger also reported that the ground was soft and partially plowed with furrows approximately 3 inches deep.

Prior to the FAA arrival, the aircraft was moved to the Travland Helicopter's hangar located on Mathis Field Airport, San Angelo, Texas. A representative from the Schweizer Aircraft Corporation inspected the damage to the helicopter and removed the tailboom forward attachment fitting.

Examination of the helicopter by the FAA inspector and the aircraft manufacturer revealed that the tailboom forward attachment fitting had separated at the attaching bolt hole. The vertical and horizontal stabilizers were damaged. The left forward diagonal tailboom support brace was bent. Both tail rotor blades were attached to the hub and fork; however, one blade had dirt on the leading edge and a small break in the skin on the trailing edge. The other blade was found fractured and separated in the spar root area at the end of the hub spindle, and there was a dent in the leading edge near the tip. The tail rotor drive shaft was found twisted and disengaged from the upper pulley aft drive adapter.

The tailboom forward attachment fitting, P/N:269A2323, and associated parts were sent to the IMR Test Labs in Lansing, New York, by the aircraft manufacturer for examination. After this examination was completed, the NTSB investigator-in-charge had the parts examined at the NTSB Materials Laboratory in Washington, DC. Both examinations concluded that the fracture surface was "consistent with an overstress failure." There were "no signs of preexisting cracks found."