As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ENG RUN UP FOR TAKEOFF, WHEN ENG REACHED 100% RPM THE ACFT EXPERIENCED AN INCREASED MAIN ROTOR VIBRATION. AFTER TROUBLESHOOTING, DETERMINED MAIN ROTOR HUB ASSEMBLY BEARINGS WORN. THIS ACFT REMAINS OUT OF SERVICE AT THIS TIME AWAITING A REPLACEMENT MAIN ROTOR HEAD ASSEMBLY.