A320 FLT CREW WHILE ON APCH TO LNDG HAS AN UNSAFE GEAR INDICATION; EXECUTES A GAR; DECLARES AN EMER AND PERFORMS THE EMER EXTENSION CHKLIST; LANDS WITHOUT INCIDENT.

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WE WERE ON A 10 MI FINAL TO RWY 16L IN DENVER. CONFIGURING FOR LNDG; WE LOWERED THE GEAR HANDLE. AFTER AN ABNORMALLY LONG WAIT AND SEEING 3 RED LIGHTS WE HEARD THE WARNING AS WE WERE CYCLING THE GEAR HANDLE. WE GOT A CLEAN CONFIGN ON GEAR AND PUT THE HANDLE BACK DOWN WHILE THE CAPT WAS STILL FLYING FINAL. WE PUT THE GEAR HANDLE BACK DOWN AND AGAIN WAITED. THIS TIME WE GOT AN UNSAFE GEAR WARNING WITH ECAM THAT CALLED FOR US TO 'GRAVITY' EXTEND THE GEAR. THE CAPT INITIATED A GAR AND WE LEFT THE GEAR HANDLE DOWN AND HANDLED THE GAR. ON BASE/DOWNWIND WE DID THE ECAM (1 STEP GRAVITY EXTENSION) WHILE SIMULTANEOUSLY REFING THE FLT MANUAL FOR CONSIDERATIONS. AFTER GRAVITY EXTENSION WE HAD A BAD INDICATION ON THE R MAIN ON BOTH THE ECAM AND THE INDIVIDUAL GEAR INDICATORS. THE CAPT BRIEFED THE PURSER TO PREPARE THE CABIN FOR EVAC AND THAT HE HAD 5 MINS. I WROTE A QUICK NOTE TO DISPATCH; BUT WE NOW HAD ONLY 4500 LBS OF FUEL. WE BEGAN REVIEWING STEPS FOR PARTIAL GEAR AND EVAC CONSIDERATIONS. OUR FUEL WAS BURNING QUICKLY (NOW LOWER 3000'S) BEING IN LEVEL FLT WITH GEAR/DOORS. THE CAPT CALLED APCH FOR IMMEDIATE VECTOR TO RWY 16R AS FIRE TRUCKS WERE READY FOR US AND WE DIDN'T WANT TO GET LOWER ON GAS (NOW 17 MI OUT). AS WE TURNED TOWARD FINAL THE CAPT CALLED FOR FLAPS 2 DEGS AND AS THEY CAME OUT IN THE TURN THE GEAR CAME DOWN AND WE HAD 2 GOOD INDICATIONS (ECAM AND INDIVIDUAL INDICATOR). WE CONTINUED THE FINAL APPROACH AS IF IT WAS BAD AND GAVE A BRACE SIGNAL TO THE CABIN. LNDG WAS UNEVENTFUL. FLT ATTENDANTS DID A PHENOMENAL JOB IN SHORT TIME OF PREPPING THE FOLKS FOR EVAC AND BRINGING THE SIT TO A GOOD CONCLUSION. WE WERE TOWED TO THE GATE. NO INJURIES OCCURRED. SUPPLEMENTAL INFO FROM ACN 698239: WITH THE FUEL SIT A MAJOR CONCERN WE NOTIFIED DISPATCH; DECLARED THE EMER AND NOTIFIED THE PURSER TO PREPARE FOR AN EVAC. THE GRAVITY EXTENSION CHKLIST WAS ACCOMPLISHED PER ECAM BUT TO NO AVAIL. UPON THE SECOND APCH WE DIDN'T RECEIVE A GOOD INDICATION UNTIL WE EXTENDED FLAPS TO 2 DEGS. WE LANDED UNEVENTFULLY BUT HAD TO BE TOWED OFF THE RWY DUE TO NO NOSEWHEEL STEERING.