What happened
During an IFR flight, a pilot encountered low instrument meteorological conditions shortly after departure. Although the pilot had filed an IFR flight plan, no weather briefing was requested or provided prior to the flight. During the flight, the pilot communicated an intention to return to the departure airport, though no specific reason for the turnaround was provided, and no emergency was declared. The final communication from the cockpit indicated that a previously noted issue had been resolved and that the flight would proceed to its intended destination.
Witnesses at the scene observed the engines running at unsynchronized speeds and noted that the propellers appeared to be cycling. Additionally, dark smoke was seen trailing from the right engine. The aircraft subsequently impacted one ridge, traveled approximately 1,000 feet through the air, and struck a second ridge, resulting in a post-impact fire. Both propellers exhibited significant damage consistent with high rotational speeds at the time of impact.
Findings
Investigations into the mechanical components, including the engines, propellers, and turbochargers, did not identify a specific mechanical failure that would have necessitated the pilot's initial decision to return to the airport. However, an examination of the right engine's internal parts revealed black discoloration, which a representative from Textron Lycoming identified as evidence of an excessively rich fuel mixture.
Regarding the pilot, medical and toxicological records indicated a history of mental health challenges, including depression and bipolar disorder, as well as a history of substance abuse. Postmortem toxicology results confirmed the presence of the antidepressant Fluoxetine and its metabolite, Norfluoxetine, along with the opiate Hydrocodone.