What happened
The pilot was performing low-altitude maneuvers to herd antelope when the helicopter struck the terrain. The impact resulted in the total destruction of the aircraft. Although the pilot remained conscious immediately following the accident, he passed away approximately three hours later.
Prior to his death, the pilot stated that the engine had lost power during the flight.
The investigation
Investigators examined the wreckage and determined that the aircraft impacted the ground in a nose-low attitude with a left bank. Evidence found on all three main rotor blades indicated high flapping angles at the time of impact.
Mechanical inspections of the engine and aircraft components were conducted to investigate the pilot's claim of power loss. However, no preimpact part failure or malfunction of the aircraft or engine was identified that could have caused a loss of power.
Findings
Toxicology analysis of the pilot's blood, liver, and kidney revealed levels of nordiazepam at 0.104 mg/L, 0.846 mg/L, and 0.427 mg/L, respectively. The toxicologist noted that the therapeutic range for nordiazepam in the blood is between 0.02 and 0.18 mg/L. Nordiazepam is a sedative and central nervous system depressant that is not approved for use while flying.