N121CC

On December 16, 1999, at 1045 central standard time, a Cartercopters Cartercopter experimental prototype gyroplane, N121CC, registered to and operated by Cartercopters LLC of Wichita Falls, Texas, was substantially damaged during a hard landing following an aborted takeoff at the Olney Municipal Airport near Olney, Texas. The airline transport pilot and crewmember were not injured. Visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 test flight. The local flight was originating at the time of the accident.

For the first test flight of the day, the prototype gyroplane's rotor was pre-rotated to 450 rpm, instead of the normal 550 rpm. As the takeoff was initiated on runway 22, the collective was raised in a "normal" manner and liftoff was accomplished within 100 feet. "Within a few seconds into the climb, the control forces began to build, and stick shake began." The pilot had to use both hands to apply forward cyclic pressure to "counter" the nose pitching up. From this point, "control was almost lost," and required continued use of both hands on the cyclic. The pilot stated that he momentarily removed one hand from the cyclic to reduce power [collective]. At this time, the nose pitched up and power was reapplied to cushion the touchdown. "Application of power was not smooth and resulted in a hard landing, causing the blades to hit the rudders."

The pilot reported that after reviewing the flight data, it "became apparent that had the collective been lowered shortly after liftoff, the rotor RPM would not have dissipated so rapidly, causing the high control forces and blade flapping."