Accident Details
A helicopter operating a powerline patrol flight with three occupants on board crashed after maneuvering to avoid overhead wires. The pilot sustained fatal injuries when the transmission sheared and moved forward during the impact.
Sequence of Events
The flight was proceeding along a powerline with a tailwind. The pilot began to climb over a hill but informed passengers that he could not out-climb it. He then circled to the right to gain additional airspeed to top the hill. After clearing the hill, the pilot descended on the left side, approximately 10 feet above the powerline, with an airspeed between 0 and 20 knots.
About one-quarter mile down the hill and 200 feet lower in elevation, the helicopter approached another line crossing the one being patrolled. At that moment, the helicopter entered a steep turn over the patrol line and beneath the crossing line. The helicopter avoided the wires but subsequently crashed.
Investigation Findings
Examination revealed that the transmission sheared during the crash sequence and moved forward, causing fatal injury to the pilot. The passengers suspected a power loss, but no pre-crash mechanical failure was identified. Advisory Circular 61-13B warns of possible 'settling with power' during steep power approaches near zero airspeed.