C-FIVS, a Boeing 777-300 aircraft operated by Air Canada, was conducting flight ACA001 from Toronto/Lester B. Pearson Intl, ON (CYYZ) to Tokyo/Haneda, Japan (RJTT) with 15 crew members and 365 passengers on board. During cruise flight approximately 1200 nm North East of RJTT, the flight crew noted a decreasing oil quantity on the number 2 engine (GE90-115B). The flight crew continued to monitor the indication and subsequently elected to shut the engine down while in Tokyo airspace. A MAYDAY was declared, and the aircraft landed without incident 35 minutes later on Runway 23. The aircraft stopped on the runway for inspection, and was authorized to taxi to the gate.
The operator’s maintenance found the oil pressure line from the fuel/oil heat exchanger to the number 4 bearing was leaking.
The line was replaced and the aircraft was returned to service