Accident Overview
A helicopter conducting a tour flight sustained damage during a hard landing following a loss of tail rotor control. The pilot performed an emergency landing, and the helicopter landed hard after encountering a gust of wind.
Examination of Tail Rotor System
Post-accident examination of the tail rotor system revealed that the tail rotor control rod had failed approximately 6.5 inches forward of its aft attach point, where the control rod connects to the tail rotor pitch change bell crank. The control rod fractured perpendicular to its longitudinal axis, exhibiting a flat fracture surface.
Metallurgical Analysis
Metallurgical examination of the fracture determined that the control rod failed due to fatigue cracking that propagated from the outside inward. The origin of the crack could not be identified because of severe mechanical damage caused by relative movement between the fracture mating surfaces. Due to this damage, the size of the crack could not be determined, and therefore an assessment of the crack's age was not possible.
Inspection History
It was not possible to determine whether the crack would have been visible during the last inspection, which occurred 91.2 hours prior to the accident. The inspection checklist for that maintenance event required the removal and inspection of the tail rotor control rod.