On June 14, 2015, about 1025 central daylight time, a Weatherly 620A airplane, N4659N, lost engine power near Van Horn, Texas. The airline transport rated pilot received serious injuries and the airplane was substantially damaged. The airplane was registered to Devil Dusters, Inc., and operated by Guadalupe Ag Services, Dell City, Texas, under the provisions of the 14 Code of Federal Regulations Part 137 as an agricultural flight. Visual meteorological conditions prevailed at the time. The flight originated from the Culberson County Airport (KVHN), Van Horn, Texas. The pilot was conducting spray operations on a pecan orchard and had already completed two runs. He stated that on the third run, the engine starting missing like the magnetos were failing. After he dumped the load, he looked for a place for a forced landing. The pilot recalled that prior to the first run the airplane had about 47-48 gallons of fuel on-board; 27 in the left side tank and 20 on the right. A post-crash fire consumed much of airframe and cockpit. During the forced landing, the airplane's engine separated from the airframe and substantial damage was sustained to the right wing. Due to the remote area, an on-scene investigation was not conducted; a reason for the loss of engine power was not determined.