On August 29, 1997, at 1510 hours Pacific daylight time, a Cessna T210M, N761HQ, overshot the landing runway and impacted a fence and terrain at South County Airport, San Martin, California. The aircraft was substantially damaged, and the airline transport pilot was not injured. Visual meteorological conditions prevailed for the post-maintenance check flight. The flight departed from the San Jose International Airport about 1430. The pilot told an inspector from the San Jose Flight Standards District Office that he was conducting the check flight of the aircraft following an annual inspection, which was completed the prior day. While in cruise flight, the engine lost power and he attempted to glide to runway 32 for an emergency landing. He overshot the 3,100-foot-long runway and went off the departure end. The inspector reported that when the engine was uncowled, the bolt which connects the throttle control to the throttle body actuator arm was missing. The bolt was found in the bottom of the cowling, but the nut was not located. Subsequent investigation revealed that, during maintenance associated with the inspection, the throttle, propeller and mixture control cables had been replaced. The bolt found in the bottom of the cowling was an improper type that did not comply with an applicable Airworthiness Directive. In his report to the Safety Board, the pilot stated that after the throttle control separated, the engine may not have gone completely to the idle power position and the resulting partial engine power may have contributed to the landing overshoot. The pilot stated that he was wearing a headset and could not hear the engine well enough to detect a partial power condition.