On July 26, 1995, about 0730 Alaska daylight time, N8792D, a Piper PA-18, collided with terrain during an uncontrolled descent while approaching to land and was substantially damaged at Kustatan airstrip, near Tyonek, Alaska. The commercial pilot and his passenger were not injured. Visual meteorological conditions prevailed and no flight plan had been filed. The personal flight departed from Merrill Field in Anchorage, Alaska, and was conducted under 14 CFR 91. According to the pilot, the intended destination was a private grass airstrip used by fishermen along the Kustatan River near Tyonek. He stated that while turning left from base to final, the airplane "entered into what appeared to be a stall/spin" and "fell out" onto the ground from an altitude of about 100 feet. The airplane impacted in a swamp about 200 feet from the approach end of the airstrip. The left wing was substantially damaged. The pilot further stated that there were no preimpact mechanical malfunctions.