AN MD80 FLT CREW DIVERTS TO ANOTHER ARPT WHEN HAVING PROBS ASCERTAINING THE STATUS OF THEIR LNDG GEAR WHEN UNABLE TO REPLACE A DEFECTIVE LNDG GEAR INDICATING LIGHT DURING A NIGHT OP; LNDG AT JFK; NY.

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ON APCH TO LNDG AT LGA AFTER THE LNDG GEAR WAS LOWERED; THE R MAIN GEAR DID NOT ILLUMINATE GREEN. THIS WAS AT APPROX XA00 WITH 8000 LBS OF FUEL. I MADE A DETERMINATION THAT WE WOULD NOT TOUCHDOWN WITH LESS THAN 5000 LBS OF FUEL. WE RAN THE CHKLISTS AND EVENTUALLY CAME TO THE RECOMMENDED LIGHT BULB CHANGE. A SIGNIFICANT AMOUNT OF TIME WAS SPENT TRYING TO LOCATE THE SPARE BULB KIT SINCE IT WAS HIDDEN BEHIND A POPULAR MAKESHIFT AREA TO STORE SOME COCKPIT CHKLISTS. THERE SEEMED TO BE SOME UNFAMILIARITY ON THE PART OF THE FO WHO WAS NOT SURE OF ITS EXACT LOCATION. I EVENTUALLY FOUND THE KIT AFTER STRIPPING THE AREA OF THE COCKPIT JUMPSEAT CHKLIST AND SEVERAL CABIN EMER BRIEFING CARDS. AS LUCK WOULD HAVE IT; AT THIS PRECISE MOMENT THE FO LOST THE HOUSING WHICH CONTAINED THE LIGHT BULBS IN QUESTION TO THE FAULTY R LNDG GEAR INDICATION. I DID NOT WANT TO SPEND TOO MUCH TIME LOOKING FOR THE LOST PART SINCE FUEL WAS A QUESTION; SO I HAD THE FO CHK THE VIEWING PORTS IN THE MAIN CABIN TO DETERMINE IF THE R LNDG GEAR WAS DOWN AND LOCKED. IT WAS NOT CRYSTAL CLR TO THE FO THAT THE MAIN GEAR IN QUESTION WAS DOWN AND LOCKED AFTER THAT CHK. IN THE MEANTIME; I APPRISED SEVERAL DIFFERENT ATC CTLRS THAT I WAS 99% SURE IT WAS NOTHING MORE THAN AN INDICATION PROB. I ALSO ADDED THAT IF WE COULD NOT COMPLETELY ASCERTAIN THAT THE R MAIN LNDG GEAR WAS DOWN AND LOCKED WE WOULD TREAT IT AS AN EMER; LAND AT JFK INSTEAD OF LGA ON THE LONGEST AVAILABLE RWY AND REQUEST THE CFR EQUIP IN THAT EVENTUALITY. WE RAN THE EMER GEAR EXTENSION PROC AND NOTIFIED ATC OF OUR LNDG AT KENNEDY ON RWY 31L. ON APCH; THE FO FOUND THE LIGHT BULB HOUSING AND RECOMMENDED WE TRY THE LIGHT BULB CHANGE. I DECLINED THE SUGGESTION SINCE WE WERE APCHING 5000 LBS OF FUEL. I QUESTIONED WHETHER WE SHOULD STOW THE EMER HANDLE INSTEAD. WE TOUCHED DOWN NORMALLY AND HAD MAINT AND THE CFR CREW SECURE THE LNDG GEAR DOORS. THERE SEEMED TO BE A PROB STOWING THE EMER GEAR EXTENSION LEVER SO THAT WE COULD TAXI. THE DOORS WERE SUSPENDED OFF THE GND WITH ROPE. WHILE THIS WAS BEING ACCOMPLISHED; THE FO CHANGED THE LIGHT BULBS AND WE NOW POSITIVELY HAD A DOWN AND LOCKED (GREEN) INDICATION. AT THE GATE AFTER SOME CONFUSION; MAINT FIGURED OUT HOW TO STOW THE EMER GEAR EXTENSION HANDLE AND SHARED THAT INFO WITH THE FO AND MYSELF. I CHKED THE LNDG GEAR DOORS WITH MAINT AND SURPRISINGLY THERE WAS NOT ANY DAMAGE AT ALL TO THEM. UPON REFLECTION; ONCE I ARRIVED HOME; I CHKED OUT THE EMER GEAR EXTENSION PROC AND IT DOES STATE IF THE R HYD SYS IS PRESSURIZED TO STOW THE EMER GEAR EXTENSION LEVER.