47 G N43762 accident near North Little Rock, Arkansas

Probable cause

The flight instructor’s failure to maintain adequate rotor rpm during the practice touchdown autorotation, which resulted in a subsequent loss of helicopter control and impact with terrain.

NTSB analysis

The flight instructor reported that he was demonstrating a power-off touchdown autorotation to a large, open paved ramp area. He added that, while flaring the helicopter for touchdown, the rotor "seemed to run have out of energy" but that the rotor tachometer indications did not indicate a reduction in rotor rpm. The tail skid subsequently contacted the asphalt, and the helicopter bounced into a nose-low attitude. The main rotor blades then struck the pavement and the tailboom, which resulted in the complete separation of the tail rotor assembly, the partial separation of both main rotor blades, and damage to the skid gear. The helicopter rotated right about 180 degrees from the landing direction and came to rest upright.

A postaccident examination of the helicopter, including the dual tachometer indicator and the rotor tachometer indicator, found no preaccident anomalies that would have precluded normal operation. The accident sequence is consistent with an inadvertent loss of rotor rpm and subsequent loss of helicopter control.

Text from the NTSB. Open the NTSB docket for CEN15LA131 for the full record.