CEN21LA173

The pilot’s insufficient monitoring of the helicopter’s power while flying at low altitude and at low airspeed, which resulted in the loss of rotor rpm and impact with a tree and terrain.

The pilot of the helicopter stated that, while maneuvering “low and slow” with three passengers onboard, he noticed “insufficient power” and shortly thereafter, the low rotor rpm warning annunciated. He applied full throttle and attempted to regain rotor rpm but was unsuccessful. The pilot stated that he was forced to land immediately, during which the helicopter impacted a tree then terrain, resulting in substantial damage. The pilot reported that there were no mechanical malfunctions or failures of the helicopter and recommended operating “at a lower gross weight.” Postacccident examination of the helicopter revealed no anomalies that would have precluded normal operation.

On March 26, 2021, about 1515 central daylight time, a Robinson Helicopter Company R44 II, N178DF, was substantially damaged when it was involved in an accident near Dustin, Oklahoma. The private pilot and one passenger received serious injuries, and two passengers received minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 aerial observation flight. The pilot stated that while maneuvering “low and slow” with three passengers onboard, he noticed “insufficient power” and shortly thereafter, the low rotor rpm warning annunciated. He applied full throttle and attempted to regain rotor rpm but was unsuccessful. The pilot stated that he was forced to land the helicopter immediately, during which the helicopter impacted a tree then terrain, resulting in substantial damage that included damage to the main rotor, fuselage, and tailboom. The pilot reported that there were no mechanical malfunctions or failures with the helicopter, and recommended operating “at a lower gross weight.” Postacccident examination of the helicopter revealed no anomalies that would have precluded normal operation.