Primary finding
Probable cause
The failure of the pilot and company maintenance personnel during preflight and periodic inspections to identify the signs of fretting and looseness in the "red" main rotor blade pitch change horn to main rotor blade grip attachment, resulting in the helicopter continuing in service with a loose pitch change horn, separation of the pitch change horn from the blade grip, and inflight breakup of the helicopter due to the main rotor striking the tailboom. Contributing to the accident was the pilot's failure to respond to increased vibration in the main rotor system and land immediately.