Overview
Ground witnesses observed a helicopter performing a normal turn at approximately 500 feet above ground level (AGL). The maneuver was followed by a violent right turn. During the violent turn, the tail rotor assembly separated from the helicopter, and the main rotor blades coned upward. The helicopter subsequently entered a near-vertical descent and impacted the ground.
Wreckage Examination
Examination of the wreckage revealed that the tail rotor hub teetering fork bolt and both pitch change links had sustained overload fractures. The fork assembly exhibited extensive blade impact marks. Both tail rotor blades showed abrasive signatures on their trailing edges and were delaminated. The tail skid had separated and was fractured at midspan; the left side of the tail skid displayed tail rotor blade rub marks.
Metallurgical and Chemical Analysis
Metal and chemical analysis of the tail rotor blades disclosed that the epoxy bonding material had been weakened by a foreign substance. Both tail rotor blades had been x-rayed and painted 25 flight hours prior to the accident.
Pilot Information
No evidence was found to indicate that the pilot had flown a helicopter within the 11 months preceding the accident. The pilot had accumulated a total of 50 helicopter flight hours, of which 15 were as pilot-in-command.