NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The commercial pilot was conducting an agricultural aerial application flight. The pilot reported that the helicopter made an uncommanded right yaw during a turn. The pilot stated that he applied full left pedal to counter the yaw and that the helicopter centered briefly, but then the right yaw started again, which continued as the helicopter descended and impacted the ground.
Because the helicopter was likely operating out of ground effect at a high power setting, the uncommanded right yaw was likely the result of a loss of tail rotor effectiveness (LTE). According to Federal Aviation Administration guidance, the procedures to recover from LTE are early detection followed by applying forward cyclic to regain airspeed, applying right (not left) pedal to maintain rotor rpm, and reducing collective to reduce the high power demand on the tail rotor. On the basis of the available information, the pilot lost control of the helicopter when he responded improperly to the LTE by adding left pedal rather than by applying forward cyclic and right pedal and reducing collective.