What was found
CAPTAIN REPORTED THAT DURING CRUISE, THE RT ENGINE OIL QUANTITY DECREASED AND THE OIL QUANTITY REACHED 1 QUARTER DURING DESCENT, SO FLIGHT CREW ACCOMPLISHED THE QRH 7.21 AND 7.14 PROCEDURES AND SHUT DOWN THE ENGINE. ACFT WAS SENT TO THE HANGAR AND DURING OVERNIGHT CHECK MX PERFORMED RT ENGINE RUN, DETECTING OIL LEAK IN THE IDG GEARBOX CARBON SEAL. THE RT ENGINE IDG GEARBOX CARBON SEAL WAS REPLACED IAW MM 72-60-00 AND OPS TEST WAS PERFORMED IAW MM 71-00-00, ALL CORRECT.