On August 9, 1997, at 1230 mountain daylight time, a Cessna 172L, N7925G, registered to and operated by Montana Air Service as a 14 CFR Part 91 personal flight, collided with the terrain near Townsend, Montana. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane was substantially damaged and the private pilot, a pilot rated passenger, and two passengers were not injured. The flight had originated from Helena, Montana, about one hour prior to the accident. In a written statement, the pilot reported that while en route back to Helena, he spotted some cattle along a fence line. The pilot reported that he was looking for a missing bull of his, and decided to approached the mountain range at 6,500 feet mean sea level, and about 2,500 to 3,000 feet above ground level to determine if there were down drafts present. The pilot reported that there were none at this time and descended to 1,200 to 1,500 feet above ground level to circle the cattle. The pilot stated that the pilot rated passenger was flying the airplane at this time and after circling, initiated a climb of 500 feet per minute. The passenger stated that the airplane felt sluggish and the pilot took over the controls and applied full power. The pilot noted that the rpm was at 2,300 rpm and the airspeed was 95 knots then dropped to 70 knots. The pilot leveled the airplane and decreased the climb to level attitude. The aircraft was headed toward lower terrain and the pilot initiated a gradual descent, however, the airspeed continued to decrease. The pilot selected a landing spot and stated that the airplane stalled, which he recovered from prior to touchdown. During the landing roll on the rough terrain, the airplane nosed over.