Accident Details
A helicopter was being used to transport a radio to a county emergency operations center for a reception test at 500 feet above ground level (AGL). The aircraft was loaded with the radio, 27 gallons of fuel, and one passenger, and was within its weight and balance limits.
As the helicopter approached the test location and slowed in light wind (estimated from 160 degrees at 5 knots), the pilot felt a moderate vibration. He interpreted this as a tail rotor problem and reacted by adjusting the throttle and operating the pedals. The pilot stated that this action seemed only to oscillate the tail and cause a loss of lift. He also noted that the vibration slowed in frequency and became more violent.
Pilot Actions
Attempting to regain control, the pilot tried to increase engine RPM and raise the collective to gain altitude. However, the helicopter began spiraling. It then crashed on wooded terrain and began burning, but the occupants egressed.
Witness Observations
Several witnesses indicated that before the accident, the helicopter approached the area from the northeast and began slowing, as if the pilot intended to hover. It then began rotating to the right and subsequently crashed.
Investigation Findings
No preimpact part failure or malfunction was found that would have resulted in the accident. However, some binding was noted in the pitch change mechanism.