History of Flight
On May 28, 2023, at 1815 eastern daylight time, an experimental, amateur-built Luce Buttercup, registration N18263, was destroyed when it broke up in flight near Lyndonville, New York. The pilot and a pilot-rated passenger sustained fatal injuries. The flight was conducted under 14 CFR Part 91 as a personal operation. Earlier that day, the pilot had provided airplane rides during a picnic using a different aircraft. After the passenger expressed interest in flying, the pilot performed a preflight inspection of the accident airplane, and the two departed on a flight intended to last 15 to 20 minutes. The pilot occupied the left seat, and the passenger occupied the right seat. A witness reported hearing a low-flying airplane heading southwest, then observed pieces falling into an orchard before losing sight of the aircraft. Another witness saw the airplane flying southeast and banking right; as it leveled off, the left wing detached, followed by the right wing, and the airplane spun into a field. No flight tracking data was available for the accident airplane.
Aircraft Information
The accident airplane was a Luce Buttercup, built by the pilot using dimensions from the original Wittman Buttercup, for which no plans existed. The pilot produced and sold his own plans for the Luce Buttercup, which were not based on structural engineering analysis; design safety margins and limitations were unknown. There were no regulatory design requirements due to its experimental classification. The plans included a warning stating that the builder was solely responsible for craftsmanship and the outcome. During initial certification, an FAA inspector found 20 discrepancies, which were resolved, and a special airworthiness certificate was issued in December 2001. The original configuration included a Continental O-200-A engine (100 hp), an Aymar-DeMuth propeller, a maximum gross weight of 1,350 lbs, empty weight of 819 lbs, and fuel capacity of 20 gallons. At the time of the accident, the airplane had been modified with a Lycoming O-290-D2 engine (135 hp, 233 lbs) and a Prince Aircraft Company propeller. Airframe, engine, and propeller logbooks were not found, so operational times and inspection history could not be determined. Pilot and passenger weights were 212 lbs and 170 lbs respectively, per medical records.
Wreckage and Impact
The main wreckage came to rest in a field oriented on a magnetic heading of 150°. The engine and propeller were embedded about 15 ft from the main wreckage. The left and right wings came to rest approximately 1,285 ft east of the main wreckage, with internal wood wing pieces another 150 ft east/southeast. Examination of the engine and propeller found no pre-impact mechanical anomalies. Flight control continuity was confirmed, and there was no evidence of flutter. Laboratory examination of the wings, struts, horizontal stabilizer, and propeller indicated that wing separations were consistent with upward and aft bending and/or torsional loading. Fracture surfaces of wing attachment brackets and front strut fittings showed overstress separation. The thickness of rear spars matched the drawings. The left front strut fracture exhibited a flat crack through the weld, with dimpled fracture features and faint features resembling fatigue striations in a small area.
Additional Information
The NTSB inspected an original Wittman Buttercup at an Experimental Aircraft Association museum. No plans existed by Steve Wittman. The museum aircraft lacked inspection ports, limiting documentation. It had a compression rib at the sixth rib. A hand-shake comparison with a local Luce Buttercup showed no clear qualitative difference, but the workmanship and materials of that comparative aircraft were unknown.
Medical and Pathological Information
The 69-year-old pilot's last aviation medical examination was in May 2016, reporting high blood pressure and seasonal allergies. He was taking lisinopril/hydrochlorothiazide, amlodipine, omeprazole, and loratadine. He was issued a third-class medical certificate with corrective lenses, which expired in 2018; he completed BasicMed requirements in July 2022. Autopsy listed cause of death as diffuse blunt force trauma. Mild coronary artery disease was noted. Toxicology detected cyclobenzaprine, ethanol (0.4 g/hg), toluene, xylenes, methyl ethyl ketone, chloroethane, n-butanol, and other substances. The FAA lab also found gabapentin, hydrochlorothiazide, and acetaminophen; ethanol was not detected in brain or liver. The 72-year-old passenger's last medical was in March 2023, reporting high blood pressure, high cholesterol, and prediabetes, with medications including metformin, lisinopril, diltiazem, and atorvastatin. He received a third-class medical with corrective lenses and a SODA for color vision. Autopsy listed cause of death as diffuse blunt force trauma; the brain was absent due to injury. Coronary artery disease with up to 50% narrowing was found. Toxicology detected citalopram, diltiazem, and caffeine. The FAA lab also found diazepam, nordiazepam, oxazepam, temazepam, atorvastatin, meloxicam, tadalafil, and pramoxine.
Probable Cause
The NTSB has not stated a probable cause in the available source material.