On February 24, 1994, at approximately 0830 hours Pacific standard time (PST), a Bell 47G-3B-1, N73909, registered to Kenneth & Connie Owen, being operated by Pacific Air Research, Inc., and being flown by Michael D. Owen, a certificated commercial pilot, was destroyed during an autorotation landing following a loss of power while maneuvering near Gold Hill, Oregon. The pilot sustained serious injuries. Visual meteorological conditions prevailed and no flight plan had been filed. The flight, which was to have been operated in accordance with the requirements set forth in 14CFR137, was engaged in the application of herbicide. The pilot was interviewed by Deputy Larry Walters of the Jackson County Sheriff's Department on February 25, 1994 (refer to extract of case number 94-1935). He reported to the deputy that he had been spraying when the helicopter's engine "sputter(ed)" and began losing power. The pilot then attempted to execute a landing in a cleared area adjacent to a logging road. A total loss of power occurred during the approach to landing and the helicopter descended vertically for the remaining 75 feet before impacting the ground. The engine and fuel system were subsequently examined at the facilities of Medford Air Service, Medford, Oregon, on April 5, 1994. There was no reported evidence of a mechanical malfunction with the powerplant (refer to Inspector's Statement). Examination of the airframe fuel system revealed that the "fuel line crossover" which connects both fuel tanks had separated at the approximate midpoint where a "T" fitting line is welded. This line routes fuel to the engine via the gascolator and fuel shutoff (refer to Inspector's Statement and report of Thomas J. Duddy including photographs 1-3).