As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NO 1 OIL PRESSURE LOW LIGHT. OIL LEAKING NO1 SIDE. FOUND O-RING ON R/H SIDE OF OIL COOLER CUT. R/R O-RINGS ON R/H SIDE OF OIL COOLER. LEAK AND OPS CHECK GOOD. ON RETURN FLIGHT BACK OIL CONTINUED TO LEAK AND IT WAS DISCOVERED THE OIL COOLER CORE IS AT FAULT WHEN PRESSURIZED. REPLACED OIL COOLER.