As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER SITTING OFFSHORE IN MODERATE WINDS, THE PILOT NOTICED AN INCREASE IN VIBRATION LEVEL OF THE MAIN ROTOR ON THE NEXT FLIGHT. THE MAIN ROTOR CENTER CONE SET P/N 407-010-111-101 HAS A THICK TEFLON COATING ON THE INSIDE OF CONES. THIS COATING WAS DAMAGED ALLOWING THE HUB TO SHIFT. NOTE: BEFORE THE MAIN ROTOR HEAD WAS REMOVED, A MAST NUT RE-TORQUE WAS PERFORMED. NO LOSS OF TORQUE WAS FOUND.