What was found
(CAN) DURING FIREFIGHTING OPERATIONS THE PILOT NOTICED AN INCREASE IN OIL TEMPERATURE AND A DECREASE IN OIL PRESSURE. POWER WAS REDUCED AND THE PROPELLER WAS FEATHERED. THE AIRCRAFT RETURNED TO YKA. THE MAIN OIL SCREEN AND THE HIGH CAPACITY OIL SCREENS WERE REMOVED FOR INSPECTION. BOTH FILTERS HAD STEEL AND ALUMINUM CONTAMINATION. THE ENGINE WAS REMOVED AND A SERVICEABLE ENGINE QCU WAS INSTALLED. THE AIRCRAFT WAS TEST FLOWN AND RETURNED TO SERVICE.