Robinson Helicopter Company R44 II N512RT accident near Princeton, Kentucky

Probable cause

The pilot’s inadequate preflight planning in that he failed to accurately determine the takeoff weight of the helicopter, which resulted in exceeding the helicopter’s maximum weight capability.

NTSB analysis

Before takeoff to spray a nearby cornfield, the helicopter was filled with about 50 gallons of spraying solution and a passenger was onboard to assist the pilot with the navigation system. According to the pilot, shortly after takeoff, the low rotor rpm warning light illuminated, and the helicopter “just wouldn’t fly.” The pilot was unable to stay aloft and made a hard landing in a field.

An examination of the helicopter revealed substantial damage to the airframe and partial separation of the tail boom. Examination of the engine and its components revealed no anomalies that would have resulted in a loss of power.

The helicopter’s estimated takeoff weight was 2,641.4 lbs., which was 141.4 lbs. over its maximum gross weight of 2,500 lbs. After the accident, the pilot told his spouse that he knew the helicopter was “barely overweight but felt it would be fine.” Given that no mechanical anomalies were found, it is likely that the loss of rotor rpm was the result of operating the helicopter in an overweight condition.

Text from the NTSB. Open the NTSB docket for ERA21LA292 for the full record.