What was found
(CAN) THE AIRCRAFT WAS ENGAGED IN FIRE FIGHTING DUTIES WHEN ENGINE VIBRATION WAS FELT. ALL AIRCRAFT SYSTEMS WERE IN NORMAL, OPERATIONAL AND PERFORMANCE LIMITS. SUBSEQUENT TROUBLESHOOTING OF THE POWER SECTION WAS COMPLETED AND THE POWER SECTION WAS REMOVED FROM THE AIRCRAFT FOR FURTHER INVESTIGATION. PRELIMINARY TEARDOWN FOUND THAT COMPRESSOR TURBINE WHEEL HAD THREE PARTIAL BLADES MISSING. ONE BLADE WAS MISSING HALF OF ITS LENGTH AND TWO OTHERS MISSING APPROXIMATELY .1250 INCH FROM THE TIP OF THE BLADES. THE POWER SECTION IS CURRENTLY AT AN ENGINE OVERHAUL SHOP FOR FURTHER INVESTIGATION. INVESTIGATION REPORTS ARE CURRENTLY PENDING.