On July 22, 1998, at 1030 hours Pacific daylight time, a Grumman G-164A, N7442, impacted a series of telephone wires near Tracy, California, while applying chemicals to a field. The aircraft was destroyed in the subsequent ground impact sequence and postcrash fire. The commercial pilot, the sole occupant, was fatally injured. The aircraft was being operated as a 14 CFR Part 137 aerial application flight. Visual meteorological conditions prevailed and no flight plan was filed. A Federal Aviation Administration inspector from the Oakland Flight Standards District Office examined the aircraft at the accident site and reported that he established flight control continuity. He further reported that the pilot was executing his final run, dusting the last corner of the field. The aircraft proceeded straight and level, flying in a westerly direction, under the power lines. The upper left wing struck the telephone line which was strung under the power lines. A ground witness reported that he heard a "snap" and saw the airplane tumbling to the ground. The aircraft came to rest in an adjacent field facing east, approximately 300 feet from where the wires were hit. The aircraft was engulfed in flames and was subsequently destroyed. Two leading edge pieces from the upper left wing were torn from the aircraft and found approximately 60 feet from the wire contact point. In his written statement, the pilot's son, who is also the manager of the firm, reported that his father knew the telephone line was strung on the west side of the field, but stated that his father just forgot that the telephone line and cable were strung below the power lines.