What was found
(CAN) DURING LEVEL CRUISE FLIGHT, IT WAS NOTED THAT THE NR 2 ENG PARAMETERS BEGAN TO FLUCTUATE & AN INCREASE IN ITT WAS OBSERVED. THE POWER LEVER WAS PULLED BACK TO REDUCE THE TEMP & THE TORQUED REDUCED FROM 80% TO 40%. THE POWER WAS ADJUSTED AGAIN TO STABILIZE THE ENG BUT THE PARAMETERS CONTINUED TO FLUCTUATE. THE CHECKLIST WAS CONSULTED FOR AN ERRATIC ENG & THE ENG SHUTDOWN & SECURED IAW THE REQUIRED PROCEDURES. THE ACFT LANDED UNEVENTFUL & WITHOUT INCIDENT. AN INSPECTION FOUND THAT THE ENG OIL SYS HAD LEAKED INTERNALLY THROUGH THE ENG AS EVIDENCED ON THE REAR TURBINE & OUT THE EXHAUST PIPE. AN INSPECTION OF THE ENG OIL SYSTEM, OIL FILTERS, CHIP DETECTOR & EXTERNAL COMPONENTS DID NOT INDICATE ANY OTHER OBVIOUS MALFUNCTIONS OTHER THAN THE INTERNAL LOSS OF ENG OIL. THE ENG WAS REPLACED & THE ASSEMBLY REMOVED TO BE EVALUATED BY THE ENG SHOP FOR INVESTIGATION & A REPORT ON THE CAUSE OF THE FAILURE.