Accident Overview
A private pilot, experienced in operating the single-engine turboprop airplane, was conducting a personal flight with three passengers. Earlier that day, the pilot had flown uneventfully from his home airport to another airport approximately one hour away. During the takeoff for the return flight, the airplane impacted wooded terrain about 0.5 mile northwest of the departure end of the runway. There were no witnesses to the accident. The pilot's radio communications with flight service and on the common traffic advisory frequency were routine, and no distress calls were received. A postcrash fire consumed a majority of the wreckage.
Investigation Findings
Examination of the remaining wreckage revealed no preimpact mechanical malfunctions. The propeller was examined, and it was discovered that the propeller reversing lever guide pin had been installed backward. However, further examination indicated that the carbon block was in place and that the propeller was in the normal operating range at the time of impact. The airplane had been operated for about 9 months and 100 flight hours since the most recent annual inspection, which was the last time the propeller was removed from and reinstalled on the engine. Therefore, the improper installation of the propeller reversing lever guide pin likely did not cause the accident.
Pilot Medical Condition
Review of the pilot's autopsy report revealed that he had severe coronary artery disease with 70 to 80 percent stenosis of the right coronary artery, 80 percent stenosis of the left anterior descending artery, and mitral annular calcification. This combination placed the pilot at high risk for an acute cardiac event such as angina, a heart attack, or an arrhythmia. Such an event would have caused sudden symptoms including chest pain, shortness of breath, palpitations, or fainting/loss of consciousness and would not have left specific evidence in the autopsy. It is likely that the pilot was acutely impaired or incapacitated at the time of the accident due to an acute cardiac event, which resulted in his loss of airplane control.
Probable Cause
The pilot's loss of airplane control during takeoff, which resulted from his impairment or incapacitation due to an acute cardiac event.