What happened
While conducting a sightseeing tour at 1200 feet AGL, the pilot of the helicopter noticed and heard a decrease in the main rotor RPM. In response to this decay, the pilot initiated a precautionary landing on a ledge covered with boulders, located approximately 50 feet from the surf line.
As the pilot applied power to facilitate the landing, the engine failed to respond, and the main rotor RPM horn activated. Upon touchdown, the main rotor and tail rotor blades made contact with the rocks, causing the aircraft to roll onto its right side. The occupants were not injured.
The investigation
An examination of the engine was performed following the accident. Investigators discovered a fatigue crack in a steel 'T' fitting used to attach the pneumatic PG accumulator to the power turbine governor. This crack was specifically located within the channel of the fitting where the adjacent nut retention wire is wrapped.
A metallurgical examination was conducted, which found no other contributing conditions regarding the initiation of the crack.