A loss of tail rotor thrust due to the improper installation of the tail rotor assembly by maintenance personnel resulted in the pilot’s inability to maintain control of the helicopter as he began transition into forward flight from a hover, which resulted in a hard landing. Contributing to the accident was the failure of company quality control personnel to identify the improper installation of the tail rotor assembly before certifying the helicopter for flight, and the pilot’s inadequate preflight inspection.

BLOCKAGE OF THE OIL SCAVENGE PUMP BY FOREIGN MATERIAL WHICH WAS INTRODUCED INTO THE ENGINE DURING MAINTENANCE. A FACTOR WAS THE LACK OF SUITABLE TERRAIN FOR THE FORCED LANDING.