Incident Overview
During cruise flight, the pilot of a helicopter detected a severe vibration. Initially, the pilot decided to return to the departure airport but later elected to perform a precautionary landing. When the helicopter was brought to a hover, it rotated nose left. After landing and shutting down the engine, the pilot observed that the tail rotor gear box and vertical fin had separated from the helicopter.
Findings
Examination of the helicopter revealed that one of the tail rotor pitch link control rods had failed. Metallurgical analysis of the failed components found evidence of fatigue on the tail rotor pitch link control rod.
Maintenance and Inspection Issues
The manufacturer had specified an after last flight of the day (ALF) inspection, which is a detailed inspection of the helicopter that can be performed by pilots or maintenance personnel. According to the operator's Director of Maintenance, pilots were responsible for all daily checks. However, the pilot had not been trained to conduct the ALF inspection, and the FAA check airman who performed the pilot's initial FAR 135 checkride was unaware of the specifics of the ALF inspection. Additionally, the checklist found in the helicopter had not been updated with the latest, more detailed ALF inspection.