19 Dec 2020: Sonex Tailwheel

19 Dec 2020: Sonex Tailwheel (N935EK) — Unknown operator

1 fatality • Burleson, TX, United States

Probable cause

A total loss of engine power due to engine seizure. Contributing to the accident was the pilot decision not to orbit the airport, as originally planned.

— NTSB Determination

Accident narrative

On December 19, 2020, about 1430 central standard time, a Sonex light sport airplane, N935EK, was substantially damaged when it was involved in an accident near Burleson, Texas. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations 91 personal flight.

A witness reported that the airplane had been built as a kit and this was the airplane’s first flight.   A review of air traffic control information revealed that the pilot contacted the Spinks Airport (FWS) controller and requested to orbit the airport for 30 minutes at 3,500 ft. Shortly after departure, the controller asked if the pilot needed any assistance. The pilot reported that he was unable to climb and needed to return to the airport. The controller cleared the pilot direct to the airport and to land on runway 35. The pilot reported that he had a “sick engine,” and he was “just trying to make the field.” The controller reported to the pilot that smoke appeared to be coming from the engine.

A review of Automatic Dependent Surveillance–Broadcast (ADS-B) data revealed the airplane departed from FWS, turned, and flew south for about 2 miles before it turned north back to the airport. (see Figure 1.)

During the forced landing, the airplane impacted powerlines and terrain and came to rest inverted near a business about 1 mile south of the airport.

Figure 1: Airplane’s Flight Track

An engine examination revealed a light film of oil on the underside of the airplane’s fuselage. No evidence of an inflight fire was observed. A visual inspection of the engine did not reveal any obvious discrepancies in the engine or an avenue for engine oil to escape. An attempt to rotate the engine by turning the propeller by hand revealed that the engine was seized. The engine was equipped with a remote oil filter mounted on the firewall. Two oil lines from the oil filter adapter ran to the front of the engine where the engine’s oil pump was located; one line ran from the “inlet” side of the oil filter adapter to one side the oil pump. On the other side of the pump, an oil line ran to the “outlet” side of the oil filter adapter.

The oil filter was removed and cut open; small, fine metal pieces/powder were in the oil and on the filter element. Small metal pieces were seen when looking into the engine’s oil filter port and oil was present on the dip stick. The engine was not dissembled further and the source of the metal filings was not determined.

The airplane was equipped with a Dynon EMS D10 engine monitoring system. Review of recorded data did not reveal any information that could be correlated to the accident flight. The airplane’s hour meter showed 213.9 hours which was not consistent with the accident flight being the first flight for the airplane.

Contributing factors

  • Malfunction
  • Oil

Conditions

Weather
VMC, wind 300/09kt, vis 10sm

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