N569SXMartin Richard B SONEX · 2005

On September 10, 2023, about 1200 eastern daylight time, an experimental Sonex airplane, N569SX, was substantially damaged when it was involved in an accident near Dowagiac, Michigan. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. (Note: The accident time was estimated based on the departure time and nominal fuel consumption.)

The pilot departed Dowagiac Municipal Airport (C91), Dowagiac, Michigan, about 1100, for a local area flight. An alert notice (ALNOT) was issued at 2021 when the pilot had not returned. The accident site was located 4 days later in a heavily wooded area about 4 miles north-northeast of C91. An open agricultural field was about 60 yards west of where the wreckage was located. There were no known witnesses to the accident. The airplane came to rest inverted. Trees in the immediate vicinity were up to about 100 ft tall. Fresh tree breaks and a downed tree were located about 30 ft north and 25 ft northwest of the wreckage, respectively.

The aft fuselage was crushed and resting on a fallen tree. Both wings exhibited leading-edge crushing damage consistent with impact to the trees and terrain. The empennage was damaged consistent with impact forces. The flight control surfaces remained attached to the airframe, and control continuity was confirmed to the cockpit controls. The engine appeared intact and undamaged with the exception of minor impact damage to the air filter/intake assembly. The propeller was secured to the engine; however, both blades were damaged consistent with impact. The fuel tank was intact and contained about 10 gallons. The remaining fluid in the tank exhibited a blue tint and appeared consistent with 100 low lead aviation fuel. The fluid was clear and free of sediment.

Figure 1 – Accident Site

A postrecovery examination of the automobile engine revealed the ignition distributor rotor was fractured and separated from the driveshaft, as seen in figures 1 and 2. The interior of the distributor cap exhibited rotational scoring with fine powder residue but was otherwise intact. Each ignition harness lead was secure and undamaged. The engine examination was otherwise unremarkable. A new distributor cap and rotor were installed, and an engine test run was conducted. The engine subsequently started and ran normally at idle power.

Figure 2 – Distributor Housing/Cap and Rotor

Figure 3 – Distributor Rotor

According to the Federal Aviation Administration, no ADS-B data associated with the airplane or the accident flight was available. At the time of the on-scene examination, the transponder was observed in the OFF position.

The airplane was equipped with an emergency locator transmitter (ELT). However, the ELT unit was separated from its mounting cradle and the antenna cable was separated at the coaxial cable connector at the unit. The remaining portion of the cable and the airframe-mounted antenna appeared intact. The ELT switch was in the OFF position when initially observed by NTSB investigators at the accident site. During the postrecovery examination, the ELT was activated momentarily. The associated transmission was heard on an adjacent handheld transceiver tuned to 121.5 MHz.

The Corvair engine had been installed on the airframe just over three years before the accident. The last condition inspection was completed on August 14, 2022, following a Sonex Condition Inspection checklist. While the checklist included checking the distributor cap for condition and continuity, it did not specifically list inspecting the distributor rotor. At the time of the inspection, the engine had accrued 47.5 hours of operation since installation.

An autopsy of the pilot was performed by the Western Michigan University Homer Stryker M.D. School of Medicine. According to the autopsy report, the cause of death was blunt force injuries, and the manner of death was accident.

Toxicology testing performed at the FAA Forensic Sciences Laboratory found no drugs of abuse.