On June 29, 2001, about 1745 eastern daylight time, a Piper J3F-65, N40782, was substantially damaged during a forced landing after takeoff from Priebe Airport (7D5), Findlay, Ohio. The certificated commercial pilot was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the local personal flight conducted under 14 CFR Part 91. The pilot stated that he was departing on runway 21, and shortly after takeoff, the engine suddenly quit. The airplane descended, struck a utility pole, and came to rest in a soybean field. The pilot further stated that he added 5 gallons of fuel to the airplane prior to takeoff. Examination of the wreckage by a Federal Aviation Administration inspector revealed that both wings were folded downward, and the fuselage was buckled. The inspector found fuel in the fuel tank and carburetor, and it was absent of contamination. The inspector then rotated the propeller by hand, but did not observe a spark from any of the ignition leads. He then disconnected the P-leads, rotated the propeller again, and observed spark. The inspector then connected an ohmmeter to the magneto switch. When the switch was in the "BOTH" position, the ohmmeter showed the connection as grounded. Further examination revealed that two ignition switch leads were chafed, and grounded against a screw. The inspector added that the airplane was manufactured in 1941, and the chafing appeared to have occurred over a long period of time. Additionally, the chafing occurred in an area within the left-side wall of the cockpit, not normally viewed during an annual inspection.