What happened
The pilot landed the aircraft in a remote location to facilitate the transport of three U.S. Forest Service employees into a national forest. Upon landing, the employees exited the helicopter and began walking away from the aircraft.
While the helicopter remained at full operating RPM, it rocked backwards. This movement caused the tail rotor to strike a rock on the ground. The impact resulted in substantial damage to several critical components of the tail assembly.
The investigation
Examination of the aircraft revealed specific mechanical failures resulting from the tail rotor contact with the rock. The damage was extensive and affected multiple systems within the tail section.
- Tail rotor blades sustained visible damage
- The gearbox incurred structural harm
- The tail boom showed signs of impact
- The drive shaft was compromised