On March 26, 1994, about 1550 eastern standard time, a Cessna 172N, registered to International Flight School, Inc. and John Eastman, was substantially damaged during the landing roll in a field near Stuart, Florida, while on a 14 CFR Part 91 personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The private-rated pilot and one passenger were not injured. The flight originated from the St. Lucie County Airport, Fort Pierce, Florida, about 1540. The pilot stated that after takeoff the flight proceeded to the south, climbed to 2,500 feet then he reduced the throttle to 1900 rpm but did not apply carburetor heat. He leveled off at 900 feet to observe the farm of an acquaintance and applied power to 2200 rpm but the engine experienced a vibration and the rpm dropped to 1600. He verified that the mixture control was in the full rich position and applied full throttle but did not apply carburetor heat. The engine power was not restored and he elected to land in a field adjacent to the farm of the acquaintance. He landed in the field on a heading of about 300 degrees with the wind from 140 degrees at 12 knots with gusts to 15 knots. The flaps were retracted. Skid marks from the main landing gear were measured to be 470 feet which end at an elevated dirt road which crosses the field at a 90-degree angle. The nose landing gear separated from the airplane after contact with the elevated road. The broken nose landing gear strut then dug into the ground and the airplane nosed over and came to rest inverted. According to the mechanic who maintained the airplane, he examined the accident site the following day and spoke with the owner of the property. The owner of the property told him that the accident pilot had landed in the field before. A test propeller was installed on the engine which was started and found to operate normally.