As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE BEARING FAILED ON THE PROP BRAKE SPLINE SHAFT CAUSING THE RETAINING RING TO DISENGAGE FROM ITS SLOT. THE CONFIGURATION OF THE PROP BRAKE HOUSING KEPT THE SPLINE FROM DISENGAGING WITH THE REDUCTION GEARBOX BUT DID ALLOW AN EXCESSIVE AMOUNT OF OIL BLOW BY. THIS FAULT HAD NO NOTICEABLE EFFECT DURING FLIGHT AND WAS ONLY IDENTIFIED AFTER MAINTENANCE ACTION TO FIX THE OIL LEAK. THE PROP BRAKE WAS 501 HOURS FROM OVERHAUL LIMITS.