As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE FLIGHT, NOTICED FLUCTUATION IN OIL PRESSURE INDICATION ON LT ENGINE. INITIATED PRECAUTIONARY SHUTDOWN AND PROCEEDED WITHOUT INCIDENT. MAINTENANCE OPENED LOWER COWL AND FOUND IB OIL TANK SERVICE CAP DISLODGED AND LAYING IN LOWER COWLING. INSTALLED CAP AND LOCKWIRED, SERVICED OIL LEVEL AND WASHED ENGINE. PERFORMED ENGINE GROUND RUN, NO DISCREPANCIES FOUND.