What happened
During preparations for a coyote eradication mission, a HU-269C helicopter established initial radio contact with ground personnel. Approximately five minutes after this communication, all contact with the aircraft was lost. There were no witnesses to the accident reported by the ground crew.
The wreckage of the aircraft was located approximately 2 miles from its original launch point. The debris field showed evidence of a high rate of descent and a collision with terrain. At the time of impact, the engine and rotor speeds were recorded as low or non-existent.
The investigation
Investigators conducted an on-site and subsequent examination of several critical systems, including the engine, engine components, transmission, clutch, flight controls, and both the main and tail rotor drive trains. This examination revealed no mechanical malfunctions or failures in these components.
During the search of the wreckage, investigators discovered a spent shotgun shell lying loose under the seat panel. The shell exhibited a crush mark that appeared to correspond with two specific surfaces: the throttle bell crank and the correlator assembly for the right seat, where the right collective control column had been removed.
To test the impact of this finding, investigators from both the NTSB and the USDA performed numerous simulations using an undamaged HU-269C. Using identical spent shotgun shells, they determined that the presence of the shell only interfered with throttle movement toward a decreased power setting and could be overcome by applying a stronger twisting action.