AN A320 CREW; ON APCH TO LAX; EXPERIENCED AN FCU PROB; REQUIRING THE ILS TO BE FLOWN MANUALLY. A R DEV OF COURSE RESULTED IN A TWR INITIATED GAR.

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FL240 JUST E OF CIVET; I WAS GETTING READY TO ENTER LNDG FLT DATA WHEN THE MCDU DISPLAYED 'ENTER FIELD DATA' THEN 'SPD ERROR' AT CIVET. I ATTEMPTED TO CLR AND THE FO'S AND CAPT'S MCDU'S FROZE. WE CHKED THE FLT MANUAL AND ACARS MAINT. ONLY INPUT WAS TO PULL AND RESET THE CIRCUIT BREAKERS. THIS WAS ACCOMPLISHED WITH NO CHANGE. THE CAPT CONTINUED TO FLY THE CIVET 4 ARR AS I TROUBLESHOT AND WORKED THE RADIO; AND SET ALTIMETER. IT WAS DECIDED TO LOAD THE ILS RWY 25L AT LAX MANUALLY VIA THE RMP. THIS WAS ACCOMPLISHED AND THE CAPT FLEW THE APCH. WE ENTERED WX APPROX 4000 FT AND BROKE OUT AT 2000 FT. WE COULD NOT ARM THE APCH AND THE LOC FAILED TO ARM 2 TIMES. WE COULD NOT ENTER FIELD DATA; APCH; OR ACTIVATE AND CONFIRM THE NAV DISPLAY SHOWED US SLIGHTLY R OF COURSE AND THE CAPT BEGAN TO CORRECT; THEN WE BROKE OUT. THIS WAS WHEN TWR ASKED IF WE HAD THE PER COURSE AND WERE FLYING IT. I REPLIED CORRECTING; AND THEN TWR DIRECTED A GAR; HDG 180 DEGS; ALT 2000 FT; CONTACT APCH. WE APPLIED MISSED APCH PROC AND WERE VECTORED AROUND FOR ANOTHER UNEVENTFUL APCH AND LNDG. LESSONS LEARNED; XCHKS ARE DIFFERENT DUE TO MANUALLY ENTERING DATA AND COMPUTERS LOCKED UP. LACK OF FAMILIARITY WITH MANUAL ENTERY AND FLYING ILS PROCS. WE SHOULD HAVE INFORMED ATC OF OUR EQUIP DEGRADE SO CLOSER MONITORING COULD HAVE BEEN ACCOMPLISHED. SUPPLEMENTAL INFO FROM ACN 543856: SOME MINOR CONFUSION MAKING SURE RADIOS WERE CORRECTLY SETUP. DRIFTED N OF COURSE. TWR INITIATED GAR. NORMAL APCH AND LNDG FOLLOWED. MOSTLY VISUAL.