What was found
(CAN) FOLLOWING 1.8 HOUR FLIGHT AND AT BEGINNING OF APPROACH TO AIRFIELD, A BANG WAS HEARD AND A LOW POWER AUTOROTATION WAS CARRIED OUT. ROTORCRAFT WAS LEFT RUNNING FOR ENGINEER TO INSPECT. A VIBRATION WAS FELT THROUGHOUT THE CABIN (MOSTLY IN THE FLOOR) & LOWER PULLEY WAS VIBRATING. INSPECTION AFTER SHUT-DOWN REVEALED A VISUAL CRACK ON THE FORWARD PART OF SHAFT LOCATED UNDER THE BEARING (SHAFT IS STAINLESS). THE CRACK WAS 1.5 INCH LONGITUDINAL AND 2 ING AROUND THE SHAFT CIRCUMFERENCE.