Incident Overview
A helicopter was engaged in inspecting a transmission wire tower when its left skid became entangled with a power line guide. This entanglement pulled the helicopter out of its center of gravity (CG) limits. While the pilot attempted to correct the resulting instability, the main rotor blade contacted the tower and struck the tail boom, causing the tail rotor to separate.
Pilot Statement
The pilot reported that similar operations had been performed previously without incident. The pilot also stated that the crewmember responsible for inspecting the power line guide had failed to check the aircraft's clearance before signaling the pilot to maneuver toward the tower.
Sequence of Events
The inspection involved the helicopter positioning near the tower to allow the crewmember to examine the power line guide. During this maneuver, the left skid snagged the guide wire, pulling the helicopter off balance. The pilot's corrective actions were unable to prevent the main rotor blade from impacting the tower structure. The blade then struck the tail boom, severing the tail rotor assembly.