Bell 206 N49660 accident near Ozark, Alabama

Probable cause

The pilot's failure to maintain clearance from terrain while hovering, which resulted in the helicopter's skid impacting terrain, subsequent abnormal airframe vibrations, and a hard landing during the subsequent hovering autorotation.

NTSB analysis

According to the commercial pilot, he was hovering the helicopter in a field to position it for departure on a personal flight. He reported that the helicopter "moved out of ground effect," lost lift, and then began to settle. The left skid subsequently contacted terrain, and the helicopter began to roll left. The pilot arrested the rolling motion with flight control inputs, and the helicopter climbed to about 10 to 15 ft above the ground. However, the ground contact had placed the helicopter in an unusual attitude and generated a "rocking motion." Although the pilot attempted to correct for the unusual attitude, the main rotor system contacted portions of the upper cowling and the transmission, and the transmission driveshaft contacted its mounting system, which induced abnormal vibrations throughout the airframe. Due to these vibrations and the possible rotor system damage, the pilot initiated a hovering autorotation. The helicopter subsequently landed hard, which resulted in substantial damage to the tailboom.

A postaccident examination of the helicopter revealed substantial damage to the transmission drive system. The pilot reported that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.

Text from the NTSB. Open the NTSB docket for GAA15LA296 for the full record.