History of Flight
On September 29, 2023, at about 1200 eastern daylight time, an experimental amateur-built Smith Cozy Mark IV, registration N95SF, was substantially damaged during an accident near Cullman, Alabama. The pilot, who held an airline transport pilot certificate, was fatally injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
A witness and friend of the pilot reported speaking with him earlier that day. The pilot mentioned he had recently replaced the airplane's propeller governor and planned to fly to the witness's field. The witness stated the pilot occasionally performed a low flyby as a greeting and did not engage in unsafe maneuvers during such visits. While working outside, the witness heard the airplane approaching from the east. He and others observed the airplane turn north, then south, and execute a low pass. The pilot waved from the cockpit before initiating a climbing left turn. During the turn, witnesses noted an unusual "wiggle" in the rear of the airplane and heard a droning noise from the propeller with fluctuating pitch. The airplane then appeared to stall and subsequently impacted a field in a level attitude.
Aircraft Information
The pilot owned the airplane. According to interviews with witnesses and friends, the accident flight was the first following the replacement of the propeller governor with a new unit. Access for the governor replacement required removal of the rear-mounted pusher-configuration engine from its truss mount. The pilot removed and replaced the engine with assistance from an individual who was not a mechanic and whose involvement was limited. The airplane's maintenance logbooks were not located.
Wreckage and Impact Information
The airplane impacted terrain in a flat attitude in a field. Several propeller strikes were observed along the wreckage path. The wooden MT three-blade propeller remained attached to the hub, and all three blades were splintered. The fuselage was fractured, and both wing assemblies were displaced aft at the inboard fuel tanks.
Inside the cockpit, the throttle, mixture, and propeller controls were intact but had bent ends. The associated control cables remained attached and, when manipulated, moved through full travel at the engine controls. The fuel selector was positioned to the right fuel tank, which contained more than 5 gallons of fuel. A fuel sample from that tank was blue and free of debris. Fuel obtained from the source where the airplane was last refueled also tested satisfactory. No anomalies were noted in the fuel system.
All flight control surfaces remained attached, and control continuity was established from the cockpit to each surface. No anomalies were observed in the flight control system that would have precluded normal operation.
The engine remained within the cowling but was partially separated from the engine mount. All four engine mount bolts and nuts were present and tight, but the required bushings and large-area washers on the engine side of the mount were missing. Both upper engine vibration isolator bolts (truss mount to engine case) lacked the required washers beneath the nuts. The upper two engine mount bolt/nut assemblies appeared to have pulled through their respective rubber vibration isolators. The two lower engine mount bolts were severely bent and exhibited thin, non-aircraft-grade washers with hex-shaped extrusion marks consistent with the nuts bearing against the washers under load. Two of the nonstandard washers were recovered within the engine cowling near the lower attachment points.
Medical and Pathological Information
The Cullman County, Alabama, Medical Examiner's Office performed an autopsy on the pilot. The cause of death was determined to be blunt force trauma. Toxicological testing by the FAA Forensic Sciences Laboratory detected ethanol at 0.038 g/dL in blood and at 0.01 g/dL in urine; ethanol was not detected in vitreous fluid. N-butanol and n-propanol were detected in blood and not in urine or vitreous fluid. Diphenhydramine was detected at 197 ng/mL in blood and 3592 ng/mL in urine. Glucose was measured at 680 mg/dL in urine and 14 mg/dL in vitreous fluid.
Tests and Research
The airplane was equipped with an EDM-900 engine monitoring system. Data from the system included exhaust gas temperatures, cylinder head temperatures, oil temperature, oil pressure, fuel flow, and engine rpm. The data indicated that the engine was producing power throughout the accident flight and that recorded parameters were consistent with expected operating ranges. The final seconds of data showed a rapid decrease in rpm and fuel flow, consistent with a sudden loss of power associated with ground impact.