Incident Overview
A helicopter was utilized to transport workers and rigging to the top of a transmission tower. The operation involved placing personnel and equipment on designated spots on the tower structure. The pilot, on his third flight of this type, had been previously instructed that landing on the tower's 'bridge' was not a desired location. During a pre-flight briefing, the pilot informed the work crew that he would disembark them on the 'goats peak' and would not land on the bridge.
Sequence of Events
The helicopter took off and successfully placed one worker on the north 'goats peak.' Contrary to the plan, the helicopter then landed on the 'bridge' to offload the second worker and rigging. After the worker and rigging were clear, the helicopter began to back away from the bridge. At that moment, the main rotor system made contact with the tower structure. Subsequently, the helicopter descended and impacted the terrain below.
Environmental Conditions
Witnesses on the surface estimated the wind to be from the southwest at 15 knots at the time of the event.
Damage
The main rotor system struck the tower, and the helicopter impacted the terrain, resulting in damage to the aircraft.
Pilot Experience and Training
The pilot had been briefed prior to the operation that landing on the bridge was not preferred, and he had been given instructions to use the goats peak locations instead. Despite this, the pilot chose to land on the bridge during the final approach.
Operational Context
The helicopter was performing a specialized task involving precision placement of personnel and equipment on a transmission tower. Such operations require careful consideration of landing zones and obstacle clearance. The bridge area was not designated for landing due to proximity to tower structure.
Conclusion
The incident occurred when the helicopter's main rotor contacted the transmission tower after landing on a non-designated area and backing off. No further details on causal factors are available from the source.