What was found
NR 4 ENGINE OIL QUANTITY STEADILY DECREASED TO ZERO FROM FULL, APPROXIMATELY 1 HOUR AFTER DEPARTURE. ENGINE SHUT DOWN WHEN OIL PRESSURE LIGHT ILLUMINATED. REPLACED NR 4 ENGINE CSD DRIVE SEAL, SEAL RETAINER O-RING, CSD INPUT AND OUTPUT SHAFT PACKING PER BOEING M/M 24-11-01 AND 72-61-07. A 5 MINUTE ENGINE RUN AT IDLE AND SLIGHTLY ABOVE SHOWS NO FURTHER LEAKAGE FROM CSD DRIVE PAD DRAIN.