What was found
YYZ - CREW REPORTED NO ODORS DURING TAXI-OUT. ON TAKEOFF THRUST OUT OF CLT, AN ODOR LIKE DIRTY SOCKS WAS NOTED. AFTER THRUST REDUCTION, NO ODORS WERE PRESENT IN COCKPIT. IN CRUISE AFTER TWENTY MINUTES, FLIGHT ATTENDANT REPORTED A FOUL SMELL IN AFT CABIN (ROW 21). LAVATORIES WERE NOT THE SOURCE. FLIGHT LANDED WITHOUT FURTHER INCIDENT AT YYZ AND TAXIED TO THE GATE. MAINTENANCE BOROSCOPED BOTH ENGINES. IN NR 1 ENGINE (BOROSCOPE HOLE S5 LOOKING AFT), MAINTENANCE FOUND LIGHT TO MODERATE OIL STREAKING ON LEADING EDGE OF BLADES. NO FINDINGS IN NR 2 ENGINE. MAINTENANCE REMOVED AND REPLACED THE NR 1 ENGINE IN ASSOCIATION WITH JOB CARD 03L50671003. ALSO, REMOVED AND REPLACED HYDRAULIC PRESSURE MODULE PER MM 29-09-11.