As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE ENROUTE, THE RT ENG OIL PRESSURE DROPPED TO THE YELLOW ARC AND FLUCTUATED BETWEEN 60-70 PSI. THE RT LOW OIL PRESSURE ANNUNCIATOR STARTED FLASHING, SECURED THE RT ENGINE. PERFORMED EMERGENCY CHECKLIST, DECLARED AN EMERGENCY WITH ATC AND RETURNED TO DEPARTURE. ACFT LANDED WITHOUT FURTHER INCIDENT. REMOVED AND REPLACED RT GAS GENERATOR MODULE.