As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 4 ENGINE HAD A LOW OIL PRESSURE INDICATION. SHUTDOWN THE NR 4 ENGINE AND ENGINE MAINTAINED 6 PSI OIL PRESSURE WHILE WINDMILLING. REPLACED NR 4 OIL FILTER FOR PRECAUTIONARY PROCEDURE IAW PWA MM, CHAPTER 72-00. GROUND RAN ENGINE AND OIL PRESSURE INDICATION WAS WITHIN LIMITS, NO DEFECTS NOTED.