On July 3, 1999, about 1421 Eastern Daylight Time, a Piper PA-18-150, N4494Z, was substantially damaged during initial climb, after takeoff from the New Castle Airport, New Castle, Virginia. The certificated commercial pilot was seriously injured. Visual meteorological conditions prevailed for the local flight. No flight plan was filed for the personal flight conducted under 14 CFR Part 91. According to a witness, before fueling, the left fuel gauge indicated "EMPTY" and the right gauge indicated "1/8 Tank." The witness added 9.7 gallons to the right tank. The airplane departed the grass runway and ascended approximately 100 feet. "...the engine noises suddenly went from full power to that of idle power." The pilot made a left turn to avoid utility wires, and the airplane impacted terrain at a field adjacent to the airport. A Federal Aviation Administration (FAA) Inspector examined the wreckage at the accident site. He found no discrepancies with the flight control systems. When the propeller was rotated by hand, crankshaft continuity was confirmed, compression was attained on all cylinders, and valve train continuity was confirmed. When rotated by hand, both magnetos produced a spark. The Inspector observed the fuel selector valve in the "OFF" position. He did not observe any fuel present in the carburetor bowl or fuel strainer. He added that the fuel strainer and carburetor bowl were not compromised during the accident. He interviewed the rescue personnel, and none of the people interviewed stated that they moved the fuel selector. Additionally, the Inspector observed the metal skin, surrounding the fuel selector, buckled. He did not observe any scrape marks near the fuel selector. The Inspector noticed that the mixture cable was separated. The cable was sent to the Safety Board Materials Laboratory for further examination. According to the Materials Laboratory Factual Report, "No scraping or additional damage was noted on the outside of the wire." The Materials Engineer could not determine if the cable separated before or after the impact. According to a schematic of the fuel system, provided by the airplane manufacturer; fuel flowed from the tanks, to the selector valve, to the strainer, to the carburetor, to the mixture control, and then to engine. During an interview with the Inspector, the pilot stated that he did not remember much about the accident, including the position of the fuel selector prior to takeoff.