On October 2, 2001, about 1828 eastern daylight time, a T Bird II amateur built airplane, N673KD, was substantially damaged during a forced landing after takeoff from a private airstrip near Elberon, Virginia. The certificated private pilot sustained minor injuries, and the passenger sustained serious injuries. 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 the engine start, taxi, and run-up seemed normal. He tookoff on runway 09, a 1,800-foot long, 50-foot wide turf runway. About 50 feet above the ground, the engine lost partial power, and the pilot lowered the nose of the airplane. As the airplane descended, he then turned right to avoid tree stumps, and the airplane impacted in a soybean field, located off the right side of the runway. The pilot added that within the 60-day period prior to the accident, on two occasions, he "had trouble getting the primer bulb to prime." However, after each occurrence, the fittings and hose appeared normal. The airport manager examined the airplane after the accident. He observed fuel leaking from the fuel tank onto the ground, and a strong fuel odor was present. Further examination by the manager revealed that the primer hose, which connected the fuel primer to both carburetors, was loose. The manager could not be certain if it was loose before the impact, or if the impact loosened the hose. The airplane was equipped with a Rotax 582 engine. A Federal Aviation Administration inspector examined the engine. He was able to rotate the propeller by hand, and attain thumb compression on both cylinders. Although the fuel tank was empty when the inspector arrived at the scene, he did observe fuel in the fuel bowl. It appeared similar to automotive gasoline, and was absent of contamination. The inspector added that the fuselage was substantially damaged. Due to safety concerns, he did not attempt to check the spark plugs. An excerpt from the manufacturer's make and model engine manual revealed: "Danger! This engine, by its design, is subject to sudden stoppage! Engine stoppage can result in crash landings. Such crash landings can lead to serious bodily injury or death. Never fly the aircraft equipped with this engine at locations, airspeeds, altitudes, or other circumstances from which a successful no-power landing cannot be made, after sudden engine stoppage. Warning! Although these engine types have undergone considerable durability testing, this engine is not a certified aircraft engine. It has not received any individual safety or durability testing and conforms to no aircraft standards. It is for use in experimental and ultralight uncertified aircraft and vehicles only, in which an engine failure will not compromise safety. User assumes all risk of use and acknowledges by his use the he knows this engine is subject to sudden stoppage."