As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN FLIGHT, NR 1 ENGINE OIL PRESSURE DROPPED TO 40PSI FOR 3 MINUTES. SHUT NR1 ENGINE DOWN IAW CHECK LIST, LANDED NORMALLY WITH 1 ENGINE. INVESTIGATED, FOUND HELICOIL BACKING OUT ON INPUT SIDE OF THE OIL COOLER. FOUND O-RING ON OUTPUT SIDE SLICED. R & R OIL COOLER AND O-RINGS IAW MM 79-20-11, OPS AND LEAKED CHECKED GOOD.