As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON SHUT DOWN NOTICED POOL OF OIL ON RAMP AND THICK ALONG ENTIRE BELLY. MEASURED 5 QTS OIL REMAINING. INSPECTION REVEALED FIBER GASKET SHOWED NICK AND DEFORMATION OF OIL FILTER ADAPTER GASKET SWIFT PN FM-07. ON REMOVAL IT WAS CONFIRMED THAT GASKET ON OIL FILTER ADAPTER [F&N, NOW SWIFT] WAS DEFORMED EXACTLY LIKE EXAMPLES IN NTSB ASR-20-05 SAFETY RECOMMENDATION.