Robinson Helicopter R22 N7514S accident near Long Beach, California

Probable cause

The student pilot's failure to maintain rotor rpm during the crosswind landing approach and his subsequent improper decision to initiate an autorotation instead of applying corrective control inputs after the helicopter experienced normal airframe vibration. Also causal was his failure to raise the collective during the landing flare, which resulted in a hard landing.

NTSB analysis

During the final phase of a crosswind landing approach, the solo student pilot felt the helicopter shudder and heard the low rotor rpm horn sound. Instead of applying corrective control inputs, he immediately initiated an autorotation. He did not raise the collective control during the flare, as required, and the helicopter then landed hard and rolled over.

Postaccident examination did not reveal any preimpact anomalies with the airframe or engine that would have precluded normal operation, and the engine appeared to be operating at the time of ground impact.

Airframe vibration during the final phase of a landing approach is not an unusual phenomenon, and a low rotor rpm warning under high-load conditions (such as when landing with a crosswind) can also occur if rotor speed and engine power are not properly managed. The pilot improperly decided to initiate an autorotation instead of applying corrective control inputs to address the vibrations and improperly performed the landing flare.

Text from the NTSB. Open the NTSB docket for WPR17LA211 for the full record.