On October 6, 2007, about 1400 Pacific daylight time, a LET Blanik L-13, N510CS, collided with an airport boundary fence during final approach near Hemet, California. Orange County Soaring Association was operating the glider under the provisions of 14 CFR Part 91. The private pilot, the sole occupant, was not injured; the glider sustained substantial damage. The local area personal flight departed Hemet-Ryan Airport about 1300. Visual meteorological conditions prevailed, and no flight plan had been filed. In a written report, the pilot stated that he encountered a significant loss of lift during the latter part of the pattern, and subsequently collided with the airport boundary fence. An FAA investigator interviewed the pilot after the accident. The pilot stated that during the downwind leg, he partially deployed the flaps, and partially opened the air brake. He stated that he encountered a significant loss of lift on the final leg, but could not recall whether he closed the air brake. A photograph taken immediately after the accident by the pilot's flight instructor showed the air brake to be open. The flaps were deployed. The pilot was checked out by his flight instructor to fly the L-13 glider earlier that day. The accident flight was his first solo flight since the checkout.