On August 13, 2011, approximately 1030 central daylight time, an Air Tractor AT-402, N10119, collided with a power lines and impacted an open field during a precautionary landing near Uvalde, Texas. The commercial pilot was not injured. The airplane sustained substantial damage to the right wing, vertical stabilizer, and rudder. The airplane was registered to and operated by L&W Flying Service under the provisions of 14 Code of Federal Regulations Part 137 as an aerial application flight. Visual meteorological conditions prevailed for the flight, which operated without a flight plan. The local flight originated from Garner Field (UVA), Uvalde, approximately 0940. The pilot said that after spraying a field, the airplane's Global Positioning System (GPS) unit malfunctioned. As he attempted to troubleshoot the problem, he noticed that engine torque dropped momentarily, then returned to 1200 pounds. Shortly thereafter, engine torque dropped again and the pilot decided to make a precautionary landing on a road. While on final approach to the road, the pilot looked inside the cockpit momentarily and when he looked outside, he noticed a set of power lines crossing the road. He was able to avoid them. The pilot then saw a second set of power lines, and while maneuvering to avoid them, inadvertently stalled the airplane. The right wing dropped, striking the power lines. The airplane spun around and impacted terrain in an inverted attitude. A postaccident examination of the engine and other airplane systems showed no anomalies. The reason for the drop in engine torque was not determined.