What was found
AFTER ROTATION, GOT IRU AND GPS DO NOT AGREE ON ECAM POSITION UPDATE ACCOMPLISHED O/HEAD. ECAM WARNING STILL PRESENT AFTER UPDATE. ECAM WARNING CLEARED AND POSITIONS CAME INTO AGREEMENT O/HEAD SUBIC VOR DURING RETURN TO SFS. AFTER LANDING, IRU NR 1 DISPLAYED DRIFT 99.9, NR 2 DISPLAYED 99.9 DRIFTS AND NR 3 NO DISPLAY. REMOVED AND REPLACED FMC 1 AND 2 IAW MM 34-60-00 AND UPDATED WITH VERSION FX4-0303-001, OPS CHK SATIS. REMOVED AND REPLACED IRU NR 3 IAW MM 34-25-34 AND BAT NR 3 IAW MM 24-31-11, OPS CHK SATIS. REMOVED AND REPLACED FCC NR 1 DUE, FAULTED ON GROUND SCAN IAW MM 22-18-34, AFS/LAND TEST IAW MM 22-40-00.