The airplane was substantially damaged when it collided with terrain short of the runway at about 1455 Mountain time. The solo pilot received serious injuries; visual conditions prevailed. The pilot reported losing pitch authority while in cruise flight at 12,500 msl. He maneuvered the airplane to a nearby airport in an effort to land. However, when he lowered the landing gear, while on final to the runway, the airplane abruptly pitched over and collided with terrain. Post-accident examination of the airplane revealed that both the left and right ruddervators had separated from the stabilizer assembly during the flight.