What happened
The aircraft was engaged in an aerial application maneuver when it experienced a sudden loss of engine power. The pilot initiated an emergency autorotation to maintain control and attempt a safe landing. During the descent and subsequent touchdown, the helicopter landed with the tail section striking the ground first. This impact caused the main rotor blades to flex downward, resulting in them cutting through the tail boom. The aircraft sustained substantial damage as a direct result of this sequence of events.
The investigation
Following the accident, investigators examined the aircraft's mechanical systems and fuel components to determine the root cause of the engine failure. A thorough inspection of the carburetor bowl revealed the presence of water contamination. Further examination confirmed that water was also present within the aircraft's fuel tank and in the refueling vehicle used to supply the helicopter.
Findings
The primary factors contributing to this accident included the engine failure caused by water contamination in the fuel system. The substantial damage to the airframe resulted from the tail-low touchdown during the emergency landing procedure. The presence of water in the carburetor bowl, the aircraft fuel tank, and the refueling vehicle indicates a significant breach in fuel handling protocols that allowed contamination to enter the engine.
Safety message
This incident highlights the critical importance of strict fuel quality control and proper refueling procedures. Ensuring that fuel sources, including refueling vehicles and aircraft tanks, are free from water contamination is essential to prevent engine failures during flight operations.