AN ACR MDT CREW HAD AN ALTERNATE LNDG GEAR EXTENSION.

Narrative

WHEN THE FO CAME TO 'PTU/GEAR' ON THE CHKLIST WE NOTICED A RED GEAR LIGHT ON THE R MAIN LNDG GEAR. THE FO SAID THE GEAR WAS NOT DOWN BY VISUAL INSPECTION OUT HIS SIDE WINDOW. THE TWR CONFIRMED THE R MAIN GEAR WAS NOT DOWN. THE FO MADE A BRIEF PA TO THE PAX LETTING THEM KNOW OF THE SIT. I CALLED FOR THE EMER/ABNORMAL CHKLIST -- LNDG GEAR INDICATOR MALFUNCTION. THE FO CARRIED OUT THE ITEMS FOR THIS BUT NO GREEN LIGHT ON THE R MAIN. THE CHKLIST THEN SAID TO PROCEED WITH AN ALTERNATE LNDG GEAR EXTENSION. FO CARRIED OUT THE CHKLIST ITEMS AND THE R MAIN CAME DOWN. THIS WAS VERIFIED BY A GREEN GEAR INDICATOR IN THE COCKPIT AND VISUAL INSPECTION BY THE FO GOING BACK IN THE CABIN. APCH WAS NOTIFIED TO HAVE THE CFR STANDING BY. I DISCUSSED WITH THE FO IF AN EVAC IS NEEDED WHAT OUR DUTIES WILL BE. I CALLED THE FLT ATTENDANT AND EXPLAINED THE GEAR WAS INDICATING DOWN BUT TO PREPARE THE CABIN FOR AN EMER LNDG. I TOLD HER TO TURN ON THE FLOOR EMER LIGHTS AND PULL HER CIRCUIT BREAKERS. I GAVE HER INSTRUCTIONS ON EVACING IF NEEDED. APCH VECTORED US FOR RWY 33L. ALL CHKLISTS WERE COMPLETED AND A LNDG CLRNC WAS GIVEN. A ROUTINE APCH AND LNDG WERE MADE. AS WE TURNED OFF THE RWY; THE FO MADE A PA NO EVAC WAS NEEDED.