History of Flight
On April 24, 2009, about 1337 central daylight time, an experimental amateur-built MK-1, N91MK, was substantially damaged following an unintentional takeoff during a high-speed ground test at Demopolis Municipal Airport (DYA), Demopolis, Alabama. The pilot/owner was fatally injured. The accident flight was the first flight of the airplane, which was operated under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed.
The engine was not equipped with a starter, requiring hand-propping to start. On the day of the accident, the pilot sat in the airplane while an acquaintance hand-propped the engine. The engine idled briefly before stalling. The pilot then exited and hand-propped the engine himself while the acquaintance held the tail to prevent movement. After starting, the pilot re-boarded and closed the canopy. The acquaintance noticed a seat belt protruding; the pilot reopened the canopy to secure it and stated he would return shortly, planning only high-speed ground runs on the runway.
The pilot completed one successful high-speed ground run on runway 22 and taxied back for a second. During the second run, more than halfway along the runway, the airplane became airborne and moved erratically in all three axes. It then stabilized slightly and initially flew away from the airport on the runway heading. Witnesses reported several turns, with varying accounts of number and direction. The airport manager stated the airplane became established on a left downwind leg for runway 22. Several witnesses heard the engine sputter before it ceased operating. The airplane descended and impacted the ground at a steep angle. A post-impact fire erupted, consuming the cockpit and part of the forward fuselage and engine compartment.
Personnel Information
Federal Aviation Administration (FAA) records indicated the pilot, age 61, held a private pilot certificate with airplane single-engine and multi-engine land ratings. His most recent FAA third-class medical certificate was issued in June 2008, at which time he reported 1,200 total hours of flight experience. He also held an experimental repairman certificate issued on February 25, 2009.
According to the manager of DYA, the pilot had lived in the area for several years but first came to the airport about three months before the accident, arriving in a Cessna 150. He kept the Cessna at DYA for a few weeks and was seen flying it on several occasions. The pilot then reportedly traded the Cessna for the accident airplane.
Aircraft Information
According to FAA information, the airplane was an all-metal, single-place, low-wing monoplane with fixed landing gear and a converted Volkswagen engine of 1,915 cubic centimeters displacement. FAA documentation indicated the pilot and another individual were listed as co-builders. The airplane was first registered with the FAA in February 2009, with the pilot as sole registered owner. No construction or maintenance documentation was found at the accident site, the pilot's home, or hangar.
The co-builder stated the airplane was a "Hummel Bird" and that he began construction from plans in 1996, completing the engine and most of the fuselage before ceasing for personal reasons. He later transferred full ownership to the pilot, who traveled to Arizona to complete construction. The co-builder delivered the airplane to Alabama on a trailer with wings detached. He did not substantially assist with completion and did not recall fuel tank configuration with certainty, but believed there was a center tank forward of the instrument panel and one or more wing tanks.
The FAA-designated airworthiness representative (DAR) who signed off the airplane on February 18, 2009, stated it was an original composite design derived from two or three other designs. He noted the co-builder did most of the construction and that workmanship was "exceptionally well-constructed." The DAR recalled the fuel system consisted of a center tank and two wing tanks, with wing tanks feeding the center tank, and the airplane was equipped with an electric fuel pump and an engine-driven fuel pump. Flight controls were conventional, activated by push-pull tubes, and the maximum gross weight was 781 pounds.
The airport manager reported the pilot brought the airplane to DYA several weeks prior on a trailer with wings detached. He believed the airplane had a single fiberglass fuel tank forward of the instrument panel, above the pilot's knees. The pilot explained that a pump between the tank and engine prevented gravity feed if the pump failed. The manager advised the pilot that the fuel tank and pump arrangement was "unsatisfactory" and noted the propeller was "very small," unlikely to windmill if the engine stopped. He witnessed a previous ground test two to three weeks prior when the engine quit and the fuel tank developed leaks; he advised replacing the composite tank with a metal tank but did not know if repairs were made. The airport manager and a worker stated there was at least one other occasion when the engine stopped during ground tests, with reason unknown.
Meteorological Information
The automated weather observation at an airport 31 miles west of the accident site, about the time of the accident, included variable winds at 6 knots, few clouds at 6,000 feet, a broken cloud layer at 25,000 feet, 10 miles visibility, temperature 29°C, dew point 14°C, and an altimeter setting of 30.02 inches of mercury.
Airport Information
FAA information indicated DYA was a public airport with a single asphalt runway measuring 5,000 feet long by 100 feet wide. Airport elevation was 113 feet above mean sea level. The airport had no air traffic control tower. The DYA common traffic advisory and Unicom radio frequencies were the same, and communications were not recorded.
Wreckage and Impact Information
According to the FAA inspector, the accident site was approximately 1.9 miles east-southeast of the threshold of runway 22. The airplane impacted the ground in a nose-down attitude and came to rest upright. The site was in a grassy field with disturbed earth only under the nose; no other ground scars were present. Neither wing exhibited impact damage to its leading edge. The manufacturing joint for the left wing, about two feet outboard of the fuselage mold line, was fracture-separated at its aft end, and the left wing was canted about 10 degrees forward. The vertical stabilizer was canted several degrees aft and to the right. The two-bladed wood propeller was oriented vertically; the spinner was crushed on its lower side. The upper propeller blade was intact; the lower blade was fracture-separated approximately two inches outboard of the spinner.
The single-piece canopy transparency was fractured, with multiple fragments completely separated. Miscellaneous small items—including canopy fragments, a flight instrument, and the pilot's eyeglasses—were scattered within a 20-foot radius quarter-circle forward and to the right. A landing gear wheel and tire were found approximately 30 feet forward and to the right of the airplane. The pilot's cap was found approximately 30 feet forward and to the left.
Flight control continuity for rudder, ailerons, and elevator was established from the respective controls to the cockpit area, but fire consumed portions of the push-pull tubes near the cockpit. Detailed examinations of the engine and fuel system components were not conducted. Examination of FAA-provided photographs indicated the airplane was equipped with a fuel tank in each wing root and a fuel tank forward of the cockpit. An access door in the forward cowl contained a hand-written annotation: "100 LL Cap 9 U.S. Gal."
Medical and Pathological Information
Although requested by the FAA and the National Transportation Safety Board, neither an autopsy nor toxicological testing was performed on the pilot.