What happened
On January 8, 2020, a Hughes OH-6A helicopter, registration N6186U, was performing a public aerial observation flight near Preston, Georgia, to conduct wildlife damage management. During the flight, the pilot identified a feral swine and communicated its location to a ground crew via radio. Shortly after this communication, the pilot experienced a loss of engine power and rotor RPM.
The pilot maneuvered the aircraft away from nearby trees to perform an autorotation into an open, plowed cornfield. As the helicopter landed on the rough terrain, the aircraft nosed forward and the main rotor blades struck the ground. The accident resulted in 2 minor injuries to the pilot and one crewmember, and the aircraft sustained substantial damage.
The investigation
An FAA inspector examined the wreckage at the accident site, noting that the tail boom had separated from the helicopter and three of the four main rotor blades had separated from the hub. The fuselage also sustained structural damage. An examination of the flight control system, drive train, main rotor system, and tail rotor system showed no evidence of a preexisting mechanical malfunction.
The engine was removed and sent to an authorized overhaul facility. Testing confirmed that the N1 and N2 rotors moved freely without binding, and control continuity was established from the collective twist grip to the fuel control unit. While the control linkage to the power turbine governor was found fractured at the engine firewall, this was attributed to impact forces from the accident.
Subsequent bench tests of the power turbine governor, fuel control unit, fuel nozzle, and fuel pump all performed within manufacturer specifications. Additionally, the fuel system was found to be free of obstructions or contamination, and laboratory analysis of a fuel sample yielded normal results. The engine performed satisfactorily during a 20-minute test run on a test stand.