What was found
(CAN) PARTIAL COMM/NAVIGATION SYS FAILURE ON APPROACH. DURING APPROACH THE CAPTAIN`S MCDU WAS TEMPORARILY LOST, FOLLOWED BY A LOSS OF BOTH NDS WITH "MAP NOT AVAILABLE" FOR 5-SECONDS. BOTH RMP DISPLAYS WENT BLANK. LANDING CLEARANCE OBTAINED THROUGH YOW ARRIVAL FREQUENCY. NORMAL LANDING IN VMC CONDITIONS. TROUBLESHOOTING IAW FLEET RECOMMENDATIONS CARRIED OUT. CFDIU REPLACED IAW AMM 31-32-34 AND TESTED OK. RMP 1 REPLACED IAW AMM 23-13-13 AND TESTED OK. AMM TASK 31-21-00-750-002A CARRIED OUT TO SET ACFT CLOCK.