What happened
The pilot was performing a maneuver to compensate for a stuck left pedal when the helicopter was flown with a 5-degree yaw to the left. As the airspeed reached zero, the pilot reduced the collective to bring the nose around, which resulted in light contact with the ground.
Following this contact, ground resonance began and progressed so rapidly that the aircraft was destroyed almost immediately.
The investigation
Post-accident examination of the three blade friction dampers provided evidence suggesting that the majority of the bronze plates inside the dampers were worn beyond acceptable limits. Additionally, the pilot reported having stopped three times during the flight to re-phase the main rotor system.