Incident Details
During cruise flight, the airplane experienced a complete loss of engine power. The pilot responded by switching fuel tanks and activating the electric fuel boost pump. Despite these actions, the engine did not restart. The airplane subsequently performed a forced landing in a rocky riverbed, during which it nosed over.
A witness at the accident site observed fuel leaking from both wings and noted that the magnetos and electric fuel boost pump switches were in the ON position.
Investigation Findings
The National Transportation Safety Board (NTSB) investigator-in-charge (IIC) and a Federal Aviation Administration (FAA) airworthiness inspector conducted a post-accident examination. They operated the engine on the airplane and found no anomalies. All flexible fuel lines were removed and internally inspected, and the electric fuel pump and bypass valve were removed and tested. Additionally, all troubleshooting procedures from the IO-520 maintenance manual were followed by the IIC and FAA inspector. No anomalies were identified in any of these components.