As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) NR 2 ENGINE WAS SHUTDOWN AND PROPELLER FEATHERED DUE TO ROUGH RUNNING. THERE IS EVIDENCE OF ALUMINUM IN THE OIL SCREEN. SUSPECT PISTON FAILURE AS THE TEMPS AND PRESSURES WERE STABLE. THE ACFT WAS IN ACTIVE FIRE RETARDANT CONFIGURATION, SO THE ENGINE WAS REPLACED AS IS THE QUICKEST ACTION FOR SERVICEABILITY. FURTHER DETERMINATION OF FAILURE WILL BE ASSESSED POST FIRE SEASON.