As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE OIL LEAK FROM OIL FILTER HOUSING CAP FOUND TO BE CAUSED BY SEVERE CORROSION AROUND CAP RETAINER STUD BASES, WITH MISSING METAL MIGRATED TO O-RING SEAL AREA. INSTALLED TSO: 0.0 PN 23035102 HOUSING ASSEMBLY. RUNUP LEAK CHECKS FOUND PROBLEM RESOLVED. SUGGEST CLOSER INSPECTION THIS AREA ON AGING AIRCRAFT ENGINES DURING SCHEDULED MAINTENANCE.