A B737 CREW DECLARES AN EMER FOR A LOW FLY-BY WHEN THEY ARE UNABLE TO CHANGE THE L GEAR INDICATION LIGHT BULB. MAINT HAD INFORMED THEM THAT IT WAS NEAR TO IMPOSSIBLE TO PERFORM THAT TASK WHILE INFLT WHICH THEY HAD DISCOVERED BEFORE THE PHONE PATCH.

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ON APCH TO DFW; RWY 35C. WHEN GEAR LOWERED THERE WAS NO GREEN LIGHT FOR L MAIN LNDG GEAR. EXECUTED MISSED APCH. FO WAS PF AND I DIRECTED HE CONTINUE TO FLY AND TALK TO ATC WHILE I TROUBLESHOT AS PER BRIEFING. PRESS TO TEST OF WARNING/CAUTION LIGHTS INDICATED THAT THE L GEAR INDICATOR WAS INOP. ATTEMPTED TO CHANGE BULBS BUT WAS UNABLE TO DO SO. DECLARED EMER WITH ATC; THEN CONTACTED DISPATCH FOR PHONE PATCH TO TECHNICIAN. TECHNICIAN ADVISED IT ALMOST IMPOSSIBLE TO CHANGE GEAR INDICATOR BULBS INFLT. THEY WERE CORRECT. EXECUTED ABNORMAL PROC IN OPS MANUAL AND PERFORMED LOW APCH/FLY-BY FOR TWR TO LOOK AT GEAR. TWR ADVISED GEAR APPEARED DOWN AND LOCKED. I ASSUMED CTL OF ACFT AND TURNED DOWNWIND FOR VISUAL APCH BACK TO RWY 35C. APCH UNEVENTFUL AND EXECUTED MINIMUM RATE OF DSCNT LNDG ON RWY 35C; CLRED AT HIGH SPD AND HAD GEAR PINNED BY MAINT. UNEVENTFUL TAXI IN. EXCELLENT JOB BY DFW TRACON; DFW CFR; AND MY FO WHO PERFORMED SUPERBLY THROUGHOUT. SO CAN SOMEONE TELL ME WHY BOEING DESIGNED A PLANE WHERE THE GEAR LIGHTS CANNOT BE RELAMPED INFLT.