According to the pilot/co-owner of the experimental amateur-built glider, he assembled the glider prior to takeoff, which required that the left and right ruddervators be placed in the flight position and secured with a spring-loaded pin, inserted through three holes. The pilot stated that he visually checked that the pin was properly installed, and physically shook the ruddervators prior to takeoff. The glider was being towed for takeoff, and was approximately 6 to 10 feet above the ground, when the right ruddervator rotated toward the left ruddervator. The pilot was not able to control the glider, and disconnected from the tow plane. The glider subsequently impacted the ground, and sustained substantial damage to the fiberglass fuselage. Postaccident examination of the glider by a Federal Aviation Administration inspector did not reveal any malfunctions of the ruddervator locking mechanism. The pin required about 25 pounds of force to move, and could be heard to make a "snapping" noise when released. The inspector noted that the snapping noise was associated with the pin inserting through all three holes; however, further inspection revealed that the pin had only gone through two of the three holes. The pilot reported 338 hours of total flight experience in gliders, which included approximately 89 hours in the same make and model as the accident glider.