What was found
(CAN) PILOT REPORTED AFTER LANDING THE ACFT, & TAXING OFF THE RUNWAY HE PULLED THE CLA FROM HIGH TO LOW IDLE & THE ENG SHUTDOWN. HE ATTEMPTED TO RESTART THE ENG, BUT ABORTED THE START AS ITT REACHED 800 C. THE MECHANICS ALLOWED THE ENG TO COOL & AGAIN TRIED TO START THE ENG AT 12% NG. THE MECHANIC WAS GOING TO ADD FUEL WHEN HE NOTED THAT THE PROPELLER WAS NOT SPINNING & ABORTED THE START ATTEMPT. TRIED TO TURN THE PROPELLER BY HAND, THE PROPELLER WOULD NOT TURN & WHEN HE DID GET THE PROPELLER TO TURN HE HEARD A PIECE OF MATERIAL COME OUT OF THE EXHAUST STACK & ALL ON THE FLOOR.