What was found
IN CRUISE FLIGHT AT FL390 ECAM SHOWED YELLOW HYD RESERVOIR OVERHEAT FOLLOWED BY ECAM ACTION OVERHEAT ON LOWER DISPLAY UNIT, INDICATION FLASHED ON AND OFF THEN WENT AWAY, DIVERTED TO MCI. MX RECALLED EVENT THAT INDICATED YELLOW ELECTRIC HYD PUMP CAUSED RESERVOIR OVERHEAT. REMOVED AND REPLACED YELLOW ELECTRIC HYD PUMP. CHECK VALVE, LEAK CHECK WAS GOOD. AFTER REVIEWING HISTORY OF RECENT RESERVOIR OVERHEAT PROBLEMS NR 1 SYS DATA ACQUISITION CONCENTRATOR (SDAC) WAS IDENTIFIED AS A SUSPECT PART AND REPLACED. OPERATIONAL CHECK OF YELLOW HYD SYS GOOD. VENDOR BENCH TEST OF SDAC CONFIRMED FAILURE. UNIT FAILED ANALOG TEST DUE TO DEFECTIVE SRU. UNIT RETURNED TO SERVICE BY REPLACING THE DEFECTIVE ANALOG SRU.