As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING INSPECTION OF OIL FILTER, THE METAL RETAINING RING BETWEEN FILTER AND RUBBER GASKET (ALL PARTS INTERNAL) WAS FOUND BROKEN WITH ONE-THIRD OF THE RING MISSING. THE REMAINING PARTS OF THE RING WERE FOUND IN FILTER, ALL PIECES. FOUND ON TWO FILTERS.