On November 5, 1996, approximately 1700 eastern standard time, a Grumman American AA-1B, N9926L, was substantially damaged during a forced landing after takeoff from the Montgomery County Airpark, Gaithersburg, Maryland. The certificated private pilot/owner and passenger received minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the local flight conducted under 14 CFR Part 91. The pilot/owner arrived at the airport at 1600 to meet a perspective buyer of the airplane. The pilot stated that he "performed a preflight inspection and other local errands while waiting for the buyer to arrive." When the perspective buyer arrived, approximately 1645, they boarded the airplane, started the engine, and taxied to the runway for a closed-pattern demonstration flight. Runup, takeoff roll and rotation were all normal. The owner stated that at 200 feet the engine suddenly lost power. The owner then initiated a left turn back to the runway. The owner stated that he was unable to make it to the runway, so he attempted to land in a small vacant lot. The airplane impacted the ground, skidded across a raised road, struck trees, and continued down a steep grade where it nosed over. The pilot and passenger exited through the rear window opening. The pilot recalled that the last time he flew and fueled the airplane was in late September, when he returned to Gaithersburg from an airport near Philadelphia, Pennsylvania. The pilot stated that he thought he had a third of a tank in the left wing, and a half of a tank in the right wing, based on his flights in September. The pilot stated that he removed the caps from each wing during his preflight inspection, but, due to the design of the tanks, he was unable to see any fuel. The airplane's fuel gauges consisted of the sight glass with the float balls, on both sides of the cockpit area. The pilot stated that he could not remember looking at them, and could not recollect what the gauges indicated prior to takeoff. Examination of the wreckage by a Federal Aviation Administration (FAA) Inspector revealed no mechanical problems with the engine or its components. During his inspection of the fuel system, the Inspector found both wing tanks empty, and saw no signs of leakage or spillage. The Inspector removed the main fuel supply lines and found no residual fuel in the system. He operationally checked the fuel drains, and they functioned normally. No verification of the amount of fuel purchased, or the amount of flight time accumulated since the fuel was purchased was provided by the pilot.