A lack of previous lubrication to the tail rotor drive shaft forward fitting teeth, which resulted in their gradual wear, the eventual slippage of the shaft, and the subsequent loss of tailrotor thrust and forced landing.

THE PILOT'S ATTEMPT TO HOVER OUT OF GROUND EFFECT AT A DENSITY ALTITUDE AND GROSS WEIGHT IN TAILWIND WEATHER CONDITIONS THAT EXCEEDED THE AIRCRAFT PERFORMANCE LIMITS. FACTORS RELATING TO THE ACCIDENT WERE THE HIGH DENSITY ALTITUDE AND TAILWIND WEATHER CONDITIONS.