SONEX AIRCRAFT WAIEX — Maxwell, CA

What happened

The pilot departed in the experimental airplane for a personal flight. A review of the onboard recorded data showed that shortly before the data terminated, the airplane went from a straight and level attitude to a nose-down attitude. A review of the recorded engine parameters did not show any signatures consistent with a loss of engine power. The airplane came to rest nose down, in a flat dirt field. The wreckage, which was destroyed, sustained fire damage.

Postaccident examination did not reveal any preimpact mechanical malfunctions or failures with the airframe and the engine. No fire damage specifically related to an in-flight fire was found in the wreckage.

The pilot purchased the airplane with a partner about 1 year before the accident. According to his logbook, he had flown the airplane 26.2 hours, of which 20.0 hours were with a flight instructor.

Toxicological tests revealed ethanol was detected in lung, liver, kidney, and heart tissue samples along with N-propanol detected in lung tissue, kidney tissue, and heart tissue. Based on the pattern of toxicology results, some or all the ethanol detected in the pilot’s postmortem specimens likely was from sources other than ethanol consumption. Given the unclear accident circumstances, there was insufficient evidence to determine whether low-level ethanol effects may have contributed to the accident. The pilot’s autopsy was severely limited by the extent of the injuries sustained and therefore reduced the potential for determining if the pilot suffered from impairment or incapacitation due to medical reasons during the flight.

Based on the available evidence, it is likely the airplane departed from controlled flight for unknown reasons, entered a nose-down attitude that was not recovered from, and the airplane impacted terrain. The reason for the loss of control in flight was undetermined.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.