As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AT INSPECTION, A VERY SMALL AMOUNT OF FERROUS MATERIAL FOUND IN PRESSURE FILTER.ADDITIONAL INSPECTION FOUND A PISTON WITH BROKEN TOP COMPRESSION RING.INSPECTION OF OTHER PISTONS FOUND THEM TO HAVE BEEN WORN BEYOND LIMITS IN THE TOP RINGGROOVE WIDTH. WORN PISTONS WERE REPLACED WITH NEW.