On September 6, 1999, at 1100 central standard time (cst), a Van Grouw White Lightning, N25WL, collided with a corn crop during a forced landing following a loss of engine power. The forced landing was made in Greenfield, Indiana. The commercial pilot was not injured and the airplane received substantial damage. The 14 CFR Part 91 personal flight was operating in visual meteorological conditions without a flight plan. The flight originated from the Mt. Comfort Airport, Indianapolis, Indiana, at 1020 cst. The pilot reported that this was the first flight after having had the annual inspection on the airplane completed. He reported he departed the Mt. Comfort Airport and climbed to an altitude of 4,000 feet mean sea level (msl) over the airport. He continued to circle at this altitude for approximately 30 minutes while he checking that the airplane was functioning properly. He reported he then descended and cross the runway 25 localizer outbound to check the localizer operation. The pilot reported that after passing over the outer marker at 2,700 feet msl the engine began to lose power. He turned back toward the airport, but was unable to maintain altitude so he selected a field in which to land. The pilot reported that he believes the engine was still running when he touched down. Inspection of the airplane by an inspector from the Federal Aviation Administration Indianapolis, Indiana, Flight Standards District Office revealed the engine, propeller, and both wings were damaged during the forced landing. The inspector reported that the screw in oil plug in the bottom of the oil sump was missing and the engine had suffered from oil exhaustion.