On July 20, 2002 about 0800 Pacific daylight time, a Grumman-Schweizer G-164B, N6794K, collided with power lines and crashed into a rice field approximately 8 miles northwest of Knights Landing, California. The accident occurred while the pilot was maneuvering during an aerial application flight. The airplane was substantially damaged, and the commercial pilot was not injured. The airplane was operated by Farm Air Flying Service, Inc., Verona, California, under the provisions of 14 CFR Part 137. Visual meteorological conditions prevailed. The flight originated from Verona approximately 0730. According to responding sheriff officers and representatives from the Pacific Gas & Electric Company, the airplane came to rest upside down in a rice field after colliding with 12 KV power distribution lines. The elevation of the impacted upper line (conductor) was about 33 feet above ground level. About a 4/10-mile-long span of lines and five supporting poles were downed during the collision sequence. The pilot reported in his completed "Aircraft Accident Report," that he had observed the power lines and attempted to fly beneath them. However, he did not notice the lowest elevation line that his airplane contacted.