ERA24FA265 · Vans RV6 A

Shortly after takeoff, the airplane’s engine lost power and the pilot made a forced landing to a river. The airplane came to rest inverted in about 3 ft of water and the pilot was fatally injured. Fuel and engine performance data downloaded from the airplane’s onboard engine monitor revealed that the loss of engine was immediately preceded by a loss of fuel pressure. The data also showed that when the pilot first started the engine prior to takeoff, the left fuel tank was nearly full, and the right fuel tank was empty. The fuel selector was positioned to the right tank at the accident site. Postaccident examination of the airplane revealed that neither wing fuel tank was breached, and no evidence of any preexisting fuel leaks were observed. The engine was test-run on the airframe using the airplane’s fuel system. The engine started and ran without interruption though its full power band with the fuel selectors on both the left and right tanks. The examination of the engine and fuel system revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. An autopsy of the pilot’s remains, along with the results of postaccident toxicological testing, indicated that he had medical conditions (diabetes, high blood pressure, and atherosclerosis) that, in conjunction with his age (80 years), were associated with some increased risk of an impairing or incapacitating cardiovascular event. There was no autopsy evidence that such an event occurred, although such an event does not leave reliable autopsy evidence if it occurs just before death. The pilot’s postmortem HbA1c indicated that he had diabetes, and that it was marginally controlled in the few months prior to the accident. Toxicology results indicated that he was using diabetes medications. He was at increased risk of both abnormally high blood glucose (from diabetes) and abnormally low blood glucose (from medication effects). The negative vitreous glucose result makes it unlikely that the pilot was experiencing severe high blood sugar with major metabolic disturbance at the time of the accident. The combination of the negative vitreous glucose result with the elevated urine glucose measurement does not exclude the possibility of low, somewhat high, or fluctuating blood sugar at the time of the accident; furthermore, some common diabetes symptoms, such as fatigue and blurry vision, do not directly correspond to blood sugar values in a simple way. The pilot received a third-class aviation medical certificate roughly 8 months before the accident, and the likelihood is low that any chronic diabetes-related retinopathy or neuropathy progressed rapidly since then; however, because diabetes was not reported to the FAA as of that date, no targeted FAA evaluation for chronic diabetes complications was performed. Overall, there is no specific evidence that the pilot was impaired by effects of his diabetes at the time of the accident, although the possibility of some impairing effects, such as fatigue, blurry vision, or diminished concentration, cannot be excluded.

Verbatim NTSB analysis and probable cause from the NTSB dataset