Incident Overview
A helicopter was maneuvering at a slow airspeed approximately 50 to 100 feet above ground level when a loss of power occurred. The pilot initiated an autorotation to an open field. During the landing, main rotor rpm was low, resulting in a hard impact. The main rotor blades flexed downward and struck the tailboom, causing it to separate from the fuselage.
Examination Findings
Following the incident, an examination of the fuel system was conducted. The investigation identified organic matter that had contaminated the fuel supply.
Conclusion
The accident sequence involved a power loss while at low altitude and airspeed, leading to an autorotation with insufficient rotor rpm, and subsequent contact between the main rotor and tailboom due to blade flexure. Fuel contamination was noted in the system.