What was found
DURING CRUISE, NR 1 ENGINE OIL PRESSURE FLUCTUATED AND DROPPED BELOW YELLOW BAND. OIL PRESSURE LIGHT ON AT PILOT'S PANEL. ENGINE FAILURE CHECK LIST ACCOMPLISHED. ENGINE SHUT DOWN ON FINAL APPROACH. ENGINE OIL PRESSURE 7 PSI. FLIGHT DIVERTED TO JFK. MAINTENANCE FOUND BREATHER PRESS PORT FITTING AT MAIN GEARBOX LIBERATED DUE TO FAILED THREADS. INSTALLED BUSHING AND PLUG PER EA 72-075. REMOVED AND REPLACED MAIN OIL SCREEN PER MM 72-61-05. RAN ENGINE. OPS CHECKED NORMAL. AIRCRAFT RETURNED TO SERVICE. (X)