What was found
AT 31,000 FEET HYDRAULIC PUMP 3A PRODUCED A HYDRAULIC 3 HIGH TEMPERATURE CAUTION TEMPERATURE WAS 89 CELSIUS. SUBSTITUTED PUMP 3B FOR 3A AND TEMPERATURE REMAINED 89 CELSIUS, TURNED BOTH PUMPS OFF AND TEMPERATURE STARTED TO GET COOLER. TURNED BOTH PUMPS ON AND PRESSURE STILL DID NOT INCREASE FOR 15 MINUTES. PRESSURE RETURNED TO NORMAL. BOTH HYDRAULIC PUMPS CONTINUED TO INCREASE IN TEMPERATURE. REMOVED AND REPLACED NR 3 HYDRAULIC FLUID RESERVOIR, IAW CRY AM 29-12-30. SERVICED SYSTEM IAW CRY AM 12-12-29. OPERATIONAL CHECK GOOD, IAW CRY AM 29-10-00. RETURNED AIRCRAFT TO SERVICE. (M)