As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING THE FIRST 2500 HOUR OVERHAUL, FOUND CORROSION ON INBOARD SPLINES AND PITTING BEYOND LIMITS. PROBABLE CAUSE DUE TO BREAKDOWN GREASE. SUGGEST THAT TAIL ROTOR BUB AND BLADES ASSEMBLY NEEDS TO BE REMOVED PERIODICALLY AND SPLINES INSPECTED AND LUBRICATED WITH PROPER GREASE, THEN REINSTALLED ON AIRCRAFT. THE ABOVE PROBLEM WAS FOUND DURING THE 2500 HOUR OVERHAUL OF THE TAIL ROTOR GEAR BOX.