Robinson R22 N830J accident near Georgetown, Texas

Probable cause

A partial loss of engine power for reasons that could not be determined based on the available information, which resulted in an impact with terrain during the subsequent forced landing.

NTSB analysis

The flight instructor and commercial pilot were about to make the base leg turn for a local instructional flight when the low rotor rpm horn activated. The flight instructor got on the flight controls with the pilot, immediately reduced the collective, and applied throttle. The flight instructor heard the low rotor rpm horn stop and observed the low rotor rpm light extinguish; he visually confirmed the engine and rotor rpm were about 97%. The flight instructor began the base leg turn and heard the low rotor rpm horn again. After noticing that the engine and rotor rpm were decaying, the flight instructor felt that the engine was not capable of maintaining the rotor rpm within safe operating limits and entered an autorotation. The helicopter touched down with a small amount of forward airspeed in a yard at a private residence, which resulted in substantial damage to the tailboom and the vertical stabilizer.

A postaccident examination of the engine found no preimpact mechanical malfunctions or failures that would have precluded normal operation. Although the weather conditions at the time of the accident were conducive for the formation of carburetor icing at glide and cruise power, the helicopter was equipped with a carburetor heat assist device. The helicopter had an adequate amount of fuel on board at the time of the accident. The reason for the loss of engine power could not be determined.

Text from the NTSB. Open the NTSB docket for CEN18LA251 for the full record.