What was found
ON RIA FLT 1712 (CDG/MIA) - DURING CRUISE AT APPROXIMATELY 1830Z, NR 4 ENGINE WAS SHUT DOWN DUE TO OIL PRESSURE LIGHT ON, ENGINE OIL PRESSURE FLUCTUATING AND DECREASING BELOW 35 PSI. AT MIA ON GROUND, MAINTENANCE FOUND LEAKING GEARBOX TOWER SHAFT SEAL. SEAL WAS REPLACED, AIRCRAFT WAS RUN-UP, LEAK CHECK OK. AIRCRAFT RETURNED TO SERVICE. (X)