As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX- DEPARTED SEA HEADING FOR MFR, LEVELING AT 21,000 FT THE MASTER WARNING LIGHT FLICKERED A FEW TIME THEN CAME ON STEADY. THE NR 1 ENGINE OIL PRESSURE LIGHT WAS ILLUMINATED. STARTED THE OIL PRESSURE CHECKLIST. DURING CHECKLIST PROCESS, OIL PRESSURE DROPPED TO 20 PSI. SHUT DOWN NR 1 ENGINE. LANDED IN PDX WITHOUT INCIDENT. REPLACED THE NR 1 ENGINE AND OIL COOLER. OPS CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.