Accident Details
While cruising at approximately 2,500 feet above ground level (agl), the pilot heard a "pop" and felt the helicopter yaw to the right. Almost immediately, the engine began to lose power. The pilot lowered the collective and initiated a partial autorotation. He then attempted to accelerate the engine, but continued to hear "sputtering and popping," and the engine gradually lost more power.
Pilot Actions
The pilot elected to perform a full autorotational landing in a nearby opening within the heavily wooded area. He was able to touchdown with only a very slow forward speed. However, the terrain turned out to be a wet and muddy bog or swamp. As the helicopter touched down, one of the skids sank into the mud, causing the aircraft to roll over onto its side.
Post-Accident Inspection
A post-accident inspection of the helicopter's engine and fuel system was conducted by an FAA Airworthiness Inspector and a fixed base operator's (FBO's) maintenance personnel. The inspection did not find any evidence of an anomaly that would have led to a loss of power. After the initial inspection, the engine was mounted on an engine stand and run at various speeds for approximately eight minutes. During the test run, the engine started easily and ran smoothly at all tested speeds, up to and including a maximum of 3,100 rpm.