Incident Overview
Approximately 10 minutes after takeoff, while flying at an altitude of 300 feet above ground level (AGL) and an airspeed of 60 knots, the pilot encountered a severe vibration and a decrease in responsiveness to control inputs. The pilot initiated an autorotation to manage the descent.
Sequence of Events
As the helicopter descended during the autorotation, when it reached an altitude of approximately 10 to 15 feet AGL, the main rotor struck and separated the tail boom. Following the separation, the helicopter continued descending and impacted the terrain in a nose-first attitude.
Post-Accident Inspection
Examination of the helicopter after the accident revealed that a tension-torsion pin had failed at the location of the drag brace bolt hole. Additionally, pre-existing cracks were found extending from the pin shank to the bolt hole, indicating that the failure originated from these pre-existing flaws.