FLC OF LGT HAS CARGO COMPARTMENT SMOKE WARNING INDICATION; MOMENTARY AT FIRST; THEN CONTINUOUS. AFTER DISCHARGING THE BOTTLE THEY DECLARE AN EMER AND RETURN TO LAND.

Narrative

WE DEPARTED ORD AT XA41 CDT FOR MEX ONBOARD AN AIRBUS 320. I WAS THE CAPT AND PF. WHILE CLBING THROUGH FL310 FOR FL350; ABOUT 250 NM S OF ORD; A MOMENTARY FORWARD CARGO COMPARTMENT SMOKE WARNING APPEARED ON THE UPPER ECAM; ACCOMPANIED BY 4 OR 5 BELL RINGINGS. A FEW MINS LATER; SIMILAR; MOMENTARY WARNINGS BEGAN TO APPEAR EVERY 30/45 SECONDS. I FIRE TESTED THE SYS AND THE TEST WAS NORMAL; AS WAS THE PREFLT TEST. AFTER THE FIRST COUPLE OF WARNINGS; WE CONTACTED OUR MAINT CTR FOR GUIDANCE VIA ACARS. AFTER SEVERAL MORE MOMENTARY WARNINGS; WE GOT A CONTINUOUS VISUAL WARNING BUT NO AURAL WARNING. WE PERFORMED THE ECAM PROC BY DISCHARGING AGENT BOTTLE #1. WE THEN DECLARED AN EMER WITH ATC AND REQUESTED AN IMMEDIATE COURSE REVERSAL TO ORD AND TO DSND TO FL290 TO MAX TAS/GS. WE ADVISED OUR DISPATCHER AND HAD THE CHIEF PURSER PREPARE THE CABIN FOR A POSSIBLE EVAC UPON LNDG. I AGAIN TESTED THE SYS; BUT THE TEST DID NOT ILLUMINATE THE FORWARD CARGO SMOKE LIGHT; NOR DID WE GET AN AURAL WARNING. THE FO AND I DISCUSSED THE POSSIBILITY OF MAKING AN IMMEDIATE LNDG; BUT WE CONCURRED THAT THE WAY THE PROB DEVELOPED AND PRESENTED ITSELF; WE WERE QUITE CONFIDENT THAT WE WERE DEALING WITH AN INDICATION/SENSOR PROB. AFTER COMPLETING ALL APPROPRIATE CHKLISTS; I MADE A SMOOTH; OVERWT (150800 LBS); LNDG AT ORD AT XA54 CDT. PRIOR TO STOPPING THE ACFT; THE FO MADE A PA ANNOUNCEMENT TO THE PAX TO REMAIN SEATED WITH THEIR SEAT BELTS FASTENED WHILE THE ACFT WAS INSPECTED BY MAINT AND CRASH/RESCUE PERSONNEL. THEY WERE IN POS TO MEET THE ACFT WHEN WE STOPPED. I CAUTIONED THEM; THROUGH A DEDICATED TWR FREQ; ABOUT THE POSSIBILITY OF HOT BRAKES; AND ADVISED THEM THAT WE HAD DISCHARGED A BOTTLE OF AGENT INTO THE FORWARD PIT. FOLLOWING THEIR INSPECTION; THEY RPTED THAT NO EVIDENCE OF SMOKE OR FIRE WAS OBSERVED. AT THAT POINT; I TERMINATED THE EMER WITH THE TWR CTLR AND WE TAXIED TO PARKING. EVERY COMPONENT OF THE EMER ASSISTANCE/RESPONSE SYS WORKED TO PERFECTION. THE SYS WORKS.