On August 12, 1995, at 1430 eastern daylight time, a Schweizer 233A glider, N7592, was substantially damaged following a collision with trees while turning base for a full stop landing at North Raleigh Airport in Louisburg, North Carolina. The instructional flight was being operated under the provisions of 14 CFR Part 91 with no flight plan filed. Visual meteorological conditions prevailed at the time of the accident. Neither the flight instructor nor the pre-solo student pilot were injured in the accident. The flight departed Louisburg, North Carolina, at 1400 hours. According to the flight instructor, as they turned from the downwind leg to base during landing, they experienced a down draft. The flight instructor stated that the sink rate increased at such a rate that he could not arrest the sink rate before the glider collided with the trees. No mechanical problems were reported with the glider. The temperature was 33 degrees celsius, and the density altitude of the airport at the time of the accident was 2,762 feet.