What was found
AFTER TAKEOFF AT DTW EN ROUTE FOR PHX RECEIVED ECAM MESSAGE AUTO FLIGHT FCU 1 & 2 FAULT. ALTIMETER FLIGHT CONTROL UNIT (FCU) WINDOWS WENT BLACK, AND HAD LOSS OF AUTO THRUST & HEADING SELECT, TURNED BACK TO DTW AND LANDED WITHOUT EVENT. MAINTENANCE REMOVED AND REPLACED FLIGHT CONTROL UNIT IAW 22-81-12, OPERATIONAL CHECK WAS GOOD. BENCH TEST OF FLIGHT CONTROL UNIT S/N C12850003088 COULD NOT DUPLICATE REASON FOR REMOVAL. POWER TRANSIENT PERFORMED ON SIDE, THEN SIDE 2 WITH NFF, PREFORMED TEMPERATURE TEST AT 0ºC TO POWER, NFF. RAN ENDURANCE TEST FOR 70 HOURS, NFF. UNIT MODIFIED WITH SB C12850A-22-006.