N91MKPiper Aircraft PA 46-350P · 2014

On January 24, 2026, about 0712 central daylight time, a Piper PA-46-350P airplane, N91MK, was substantially damaged when it was involved in an accident near Sioux City, Iowa. The pilot and passenger were uninjured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot reported that after the initial climb and immediately after leveling off at 2,500 ft mean sea level, he felt the airplane make two “thugs” and observed the manifold pressure fluctuate. He subsequently observed a drop in engine oil pressure. He stated that he told the Air Traffic Control tower controller that he was going to turn back toward the airport. Once the airplane was on a north heading, a loud “boom” was heard, and a subsequent loss of engine power occurred.

The pilot executed a forced landing to a field. During the forced landing, the airplane’s engine and left wing impacted terrain and were separated. The forward fuselage and right wing sustained substantial damage.

The pilot stated that on a previous flight, four days before the accident flight, a similar “thug” was observed, but it did not result in any other abnormal indications.

The wreckage was retained for further examination.

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 the provisions of Title 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, and therefore had to be hand-propped to start it. On the day of the accident, the pilot sat in the airplane, while an acquaintance hand-propped the engine. The engine idled for a brief time before it stalled. The pilot then exited the airplane, and hand-propped the engine himself, while the acquaintance kept the airplane from moving by holding onto the tail. After the engine started, the pilot re-boarded the airplane, and closed the canopy. The acquaintance notified the pilot that a seat belt was protruding from the cockpit, and the pilot re-opened the canopy to secure the seat belt. He then informed the acquaintance that he would return shortly, since he was only planning to conduct some high-speed ground runs on the runway.

The pilot made one successful high speed ground run on runway 22, and taxied back for a second run. During the second high speed ground run, at a point that was more than half-way along the runway, the airplane became airborne, and it was observed to move erratically in all three axes. The airplane then appeared to stabilize slightly, and it initially flew away from the airport, on the runway heading. Witnesses reported that the airplane made several turns, but their accounts about the number and direction of the turns varied. The airport manager stated that the airplane became established on a left downwind leg for runway 22. Several witnesses heard the engine "sputter," and then the engine ceased operating. The airplane descended and impacted the ground at a steep angle. A post-impact fire erupted, and consumed the cockpit and part of the forward fuselage and engine compartment.

Federal Aviation Administration (FAA) records indicated that 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. The pilot also held an experimental repairman certificate, which was issued on February 25, 2009.

According to the manager of DYA, the pilot had lived in the area for several years, but he first came to the airport about 3 months before the accident, when he arrived in a Cessna 150. The pilot kept the Cessna at DYA for a few weeks, and he was seen to fly the airplane on several occasions. The pilot then reportedly traded the Cessna for the accident airplane.

According to FAA information, the airplane was an all-metal, single-place, low wing monoplane, and was equipped with fixed landing gear, and a converted Volkswagen engine of 1,915 cubic centimeters displacement. FAA documentation indicated that the pilot and another individual were listed as co-builders of the airplane. The airplane was first registered with the FAA in February 2009, and the pilot was listed as the sole registered owner. The FAA inspector reported that no airplane construction or maintenance documentation was found at the accident site, at the pilot's home, or in the pilot's hangar.

According to the individual who was listed as the co-builder, the airplane was a "Hummel Bird," and he began constructing the airplane from plans in 1996. He completed the engine and most of the fuselage, but ceased construction of the airplane for personal reasons. Sometime thereafter, when the co-builder lived in Arizona and the pilot lived in Alabama, he transferred full ownership to the pilot. The pilot subsequently traveled to Arizona, and completed construction of the airplane. Once construction was completed, the pilot returned to Alabama, and the former co-builder delivered the airplane, with the wings detached, to Alabama on a trailer.

The former co-builder stated that he did not substantially assist the pilot with the completion of the airplane. He did not recall the fuel tank configuration with certainty, but he believed that the airplane was equipped with a center tank, situated forward of the instrument panel, and one or more wing tanks. He did not recall the fuel pump configuration, or other fuel system details.

According to the FAA-designated airworthiness representative (DAR) who signed off the airplane on February 18, 2009, his role as DAR was to ensure that the FAA-required airworthiness paperwork for the airplane was completed correctly, that the workmanship, materials, and methods of construction were appropriate, and that the airplane weight and balance was in accordance with the design limitations. He stated that the airplane was an original composite design, derived by the co-builder and the pilot from two or three other designs. The DAR stated that the co-builder did the majority of the construction, and that the airplane was "exceptionally well-constructed" with respect to the workmanship. He recalled that the fuel system consisted of a center tank and two wing tanks, that the wing tanks provided fuel to the center tank, and that the airplane was equipped with an electric fuel pump and an engine-driven fuel pump. The DAR stated that the flight controls were of conventional design, that all were activated by push-pull tubes, and that the airplane maximum gross weight was 781 pounds.

According to the manager of DYA, the pilot brought the airplane to DYA several weeks prior to the accident; the airplane was on a trailer, and the wings were detached. The manager believed that the airplane only had a single fuel tank, located just forward of the instrument panel, "above the pilot's knees." He stated that the tank was made of "fiberglass," and that the pilot explained the fuel system as "having a pump between the tank and the engine, and if the pump quits, fuel will not get to the engine," since it would not gravity-feed to the engine. The manager stated that he advised the pilot that it was his opinion that the fuel tank and fuel pump arrangement was "unsatisfactory." He also stated that the propeller was "very small," and that he did not believe that the propeller would windmill in flight if the engine stopped.

The airport manager stated that he had personally witnessed the pilot conducting a ground test run on the runway two to three weeks prior to the accident; during that test run, the engine quit, and the manager helped the pilot pull the airplane off the runway. Also during that run, the fuel tank developed one or more leaks, and the airport manager advised the pilot to replace the composite fuel tank with a metal tank. The airport manager was not aware of how, or whether, the pilot repaired the leaking fuel tank.

The airport manager and an airport worker stated that there was at least one other time when the pilot was conducting ground test runs, and the airplane had to be pulled from the runway because the engine had stopped operating. Neither individual knew the reason(s) for the engine failures.

The automated weather observation at an airport located 31 miles west of the accident site, at about the time of the accident, included variable winds at 6 knots, few clouds at 6,000 feet, broken cloud layer at 25,000 feet, 10 miles visibility, temperature 29 degrees C, dew point 14 degrees C, and an altimeter setting of 30.02 inches of mercury.

FAA information indicated that DYA was public airport equipped with a single asphalt runway that measured 5,000 feet long by 100 feet wide. Airport elevation was 113 feet above mean sea level. The airport was not equipped with an air traffic control tower. The DYA airport common traffic advisory and Unicom radio frequencies were the same, and the communications on that frequency were not recorded.

According to the FAA inspector who responded to the accident, the accident site was located approximately 1.9 miles east-southeast of the threshold of DYA runway 22. The airplane impacted the ground in a nose-down attitude, and came to rest upright. The accident site was a grassy field, and except for the disturbed earth directly 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, located approximately 2 feet outboard of the fuselage mold line, was fracture-separated at its aft end, and the left wing was canted approximately 10 degrees forward from its normal orientation. The vertical stabilizer was canted several degrees aft and to the right of its normal orientation. The two-bladed wood propeller was oriented vertically, and the propeller spinner was crushed on its lower side. The upper propeller blade was intact, and the lower propeller blade was fracture-separated approximately 2 inches outboard of the spinner.

The single-piece canopy transparency was fractured, with multiple fragments completely separated from the canopy. 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 of the airplane. A landing gear wheel and tire was 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 of the airplane.

According to the FAA inspector, flight control continuity for the 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 that 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 that stated "100 LL Cap 9 U.S. Gal."

Although requested by the FAA and the National Transportation Safety Board, neither an autopsy nor toxicological testing was performed on the pilot.