Robinson Helicopter R44 N132TC accident near North Myrtle Beach, South Carolina

Probable cause

The fractured attachment lug on the forward clutch shaft yoke due to fatigue failure with multiple origins.

NTSB analysis

Seconds after liftoff to a hover, the helicopter began to “aggressively shudder.” Loud, rapid reports were heard, and the nose of the helicopter yawed to the left. The instructor assumed control of the helicopter, closed the throttle, and performed an autorotation from a hover, landing the helicopter upright on its skids; however, the airframe sustained substantial damage. The instructor completed an engine shutdown, egressed the helicopter, and noticed that the main rotor was still turning while the tail rotor remained stationary. A cursory examination of the helicopter revealed that the clutch shaft yoke fractured at one of its two bolt lugs where the yoke attached to the flex plate. All other damage depicted appeared to be impact damage from the rotating assemblies left unsecured by the fractured lug.

Examination of the damaged yoke and flexplate in the NTSB materials laboratory revealed a fractured attachment lug on the forward clutch shaft yoke due to fatigue failure with multiple origins.

Text from the NTSB. Open the NTSB docket for ERA22LA256 for the full record.