Accident Sequence
During liftoff for a banner tow flight, the top rear corner of the banner became tangled with the top front corner. The pilot continued the climb, believing the banner would untangle itself. When it did not, the pilot attempted to maneuver the helicopter and banner back to the drop point on the airport. During a slow descent, the banner rotated to a horizontal position, assumed an airfoil shape, and floated higher than the helicopter's position.
The pilot reported that he could no longer see the banner in his rear view mirror, only the tow rope extending up and aft, and was concerned that the rope might enter the tail rotor. The pilot chose not to release the banner as he descended slowly toward the drop point. Subsequently, the tow rope became entangled in the tail rotor system.
The entanglement resulted in the in-flight separation of the tail rotor and tail rotor gearbox. The helicopter began to rotate. The pilot reduced the throttle to idle in an attempt to reduce torque and rotations about the vertical axis. He then lowered the nose to gain airspeed. The helicopter impacted terrain in a near vertical attitude.
Additional Details
No information was provided about the helicopter type, registration, operator, location, date, time of day, weather conditions, ATC involvement, or occupants. The source did not specify whether any injuries occurred or the extent of damage beyond the separations described. The helicopter was equipped with both an electrical and manual release for the banner tow hook.