What was found
(CAN) WHILE ON 5TH SCENIC TOUR OF DAY, AT 2,500 FT ASL IN QUIET MODE CRUISE, A/C SOUND & VIBRATION LEVEL SUDDENLY CHANGED FROM NORMAL TO LOUD WITH HEAVY VIBRATION FROM TAIL ROTOR DRIVE AREA. PILOT IMMEDIATELY RETURNED A/C TO NORMAL MODE CRUISE RPM & EXITED SCENIC ROUTE. HE RETURNED DIRECTLY TO MAIN BASE AT PQ3 WITH PRECAUTIONARY LDG & SHUTDOWN WITHOUT FURTHER INCIDENT. TAIL ROTOR CONTROL AUTHORITY NEVER LOST. AFTER ENGINE SHUTDOWN, INSPECTION REVEALED A COMPLETELY FAILED FWD FAN SHAFT BEARING WITH DISINTEGRATED BEARING CAGE.