Amateur-built MK-1 N91MK accident near Demopolis, Alabama

Probable cause

The pilot's failure to maintain adequate airspeed following a complete loss of engine power resulting in a stall while maneuvering to land. The reason for the loss of engine power was undetermined.

NTSB analysis

The pilot and the former co-builder derived the design of the experimental airplane from one or more other experimental airplanes. The co-builder started the construction, but transferred his ownership share to the pilot, who then completed the construction. In the weeks prior to the accident, the pilot conducted several ground test runs of the airplane, presumably in preparation for its eventual first flight. On more than one occasion during the ground test runs, the engine ceased operating and the airplane had to be towed off the runway since the engine was not equipped with a starter. As of the day of the accident, the airplane had not yet been flown. That day, the pilot informed the individual who helped him start the engine that he would return shortly, since he again only planned to conduct ground test runs. The pilot completed one ground run on the runway, and taxied back for a second run. During the second run, the airplane became airborne, and it was observed moving erratically in all three axes. It stabilized somewhat, made several turns, and appeared to become established on a downwind leg in an apparent attempt to return for landing. Several witnesses heard the engine sputter and then lose power completely. The airplane then stalled at low altitude and impacted the ground at a steep angle approximately 2 miles from the airport.

Text from the NTSB. Open the NTSB docket for ERA09LA263 for the full record.