What happened
During a flight involving a practice stall maneuver, the aircraft experienced a sudden and violent rightward yaw as the throttles were advanced. As the flight instructor took control of the aircraft to attempt a recovery, both engines suffered a significant loss of power. The crew was forced to perform an emergency landing in a nearby field. During the descent and touchdown phase, the left wing of the aircraft type struck trees, which led to the aircraft being consumed by flames.
Findings
Investigations into the mechanical state of the engines revealed that while the left engine showed no notable discrepancies, the right engine had several critical issues. Specifically, a fuel controller line tee fitting was found to be cracked approximately halfway around its circumference due to ductile overload. Additionally, the turbocharger gasket on the turbine inlet side exhibited leakage across roughly 70% of its surface area.
Evidence suggests that the aircraft had previously experienced symptoms related to fuel vaporization, a condition that typically subsides when using the auxiliary fuel pump as recommended by the manufacturer. It remains unconfirmed whether the crew utilized the auxiliary pump during this specific flight. The investigation identified several contributing factors, including fuel starvation caused by leaks in the fuel system and turbocharger, as well as potential issues related to improper maintenance or installation of components.