On June 1, 1994, about 1420 eastern daylight time, N166W, a Shemp Hirth Ventus-C glider, operated by the owner/pilot, impacted terrain in Fairfield, Pennsylvania, during an uncontrolled descent. The airplane was substantially damaged. The pilot, the sole occupant, received serious injuries after falling out of the airplane while performing a maneuver. Visual meteorological conditions prevailed and a flight plan was not filed. The personal flight was initiated via aero tow from the Mid Atlantic Soaring Center in Fairfield, and was conducted under 14 CFR 91. The pilot reported that he was participating in a soaring competition at the time of the accident. He descended through the "start gate" to achieve an airspeed of 110 knots. He reported that he then "... encountered [a] sudden pitch up, probably induced by the pilot and turbulence." He subsequently "experienced heavy positive G-load and heard loud cracking sound." His hand-held radio fell loose and he tried to retrieve it. He stated that he then experienced negative Gs and an abrupt pull-up. The radio broke through the canopy. The pilot stated that he could not regain control of the glider, so he released his restraint system and fell free of the airplane through the canopy Plexiglas. He deployed his parachute and landed in a tree. He then fell about 30 feet from the tree and onto the ground, causing serious injuries. According to an FAA aviation safety inspector from New Cumberland, Pennsylvania, the glider continued to descend out of control without the pilot. It impacted terrain inverted about 3/4 miles from the pilot's landing area. An inspection of the glider revealed that both wings were buckled. The canopy frame and supporting structure remained intact, and the Plexiglas in the center of the canopy was broken. The flight controls, canopy and restraint systems were functionally tested with no mechanical deficiencies noted.