On April 23, 2000, about 1150 Eastern Daylight Time, a Cessna 150, N66430, was substantially damage during takeoff from the Fairfield County Airport, Lancaster, Ohio. The certificated private pilot and passenger received minor injuries. Visual meteorological conditions prevailed for the personal local flight. No flight plan had been filed, and the flight was conducted under 14 CFR Part 91. According to a witness, the airplane became airborne about halfway down Runway 10; it reached an altitude of 10 to 20 feet; and then descended to 5 feet. At this point, some hangars blocked the witness's view, and he thought the pilot had aborted the takeoff. The witness then spotted the airplane about 20 feet above the runway, and watched it start another descent. The witness heard the pilot declare an emergency over UNICOM, and saw the airplane execute a 180-degree turn. He then watched the airplane contacted the ground, bounce back into the air 20 to 30 feet, and contact the ground a second time before nosing over. According to a Federal Aviation Administration (FAA) Inspector, the pilot stated he experienced no mechanical failures or malfunctions with the airplane. At the accident site, another FAA Inspector verified with the pilot and passenger the following numbers; pilot's weight 250 pounds, passenger's weight 220 pounds, fuel onboard 30 gallons, and an airplane basic weight of 1,107 pounds. The combined weights equaled 1,768 pounds, about 168 pounds over the maximum gross weight of the airplane. During a subsequent interview, the pilot stated that the above numbers were incorrect. Adding that he actually weighted 220 pounds, his passenger actually weighted 205 pounds, and that the airplane had 19 gallons of fuel onboard at the time of the accident. Using the new numbers, the original Inspector determined the airplane's weight as 1,700 pounds, about 100 pounds over the maximum gross weight of the airplane. In an interview conducted by a safety board investigator, the pilot stated that he preflighted the airplane, boarded his passengers, and started the engine on the first attempt. He then taxied the airplane onto the runway, held the brakes, and advanced the throttle. The engine responded, and rpm stabilized around 2,500. The pilot released the brakes, and the airplane accelerated "normally." At 70 mph and approximately 1,000 feet down the runway, the pilot applied back pressure to the yoke, and the airplane began to climb at 200 feet per minute. Approximately 3,500 feet past the point the airplane became airborne, the pilot felt he had insufficient engine power to continue departure. The pilot added that the engine noise remained constant from takeoff, but the airspeed was decreasing. He also added that when he was 1,000 feet agl and approximately 250 feet north of Runway 10, he noticed that the power available was less than the power required for the departure. The pilot was then asked why he did not return and land on Runway 10, if he was at 1,000 feet agl with an operating engine. He had no response. The pilot reported no mechanical problems with either the engine or the airframe. At 1153 an automated weather facility located at the airport recorded the following: wind 080 degrees magnetic at 5 knots, 10 mile visibility, clear, temperature 55 degrees Fahrenheit, dew point 46 degrees Fahrenheit, and an altimeter of 29.93 inches of mercury.