Narrative:

On landing gear extension the left main indicator showed unsafe with no illumination. Executed a gentle go around at approximately 1000 ft AGL. Flew in the pvd area while troubleshooting. Swapping light fixtures and bulbs allowed the crew to confirm the gear was in fact down and safe. No emergency declared. Tower called out emergency equipment and a normal landing was accomplished. Dispatch and maintenance notified. No cabin preparation other than communication of the situation to passenger and flight attendants.

Related reports:

Google
 

Original NASA ASRS Text

Title: A B757-200 DID NOT RECEIVE A L LNDG GEAR DOWN AND LOCKED INDICATION. CREW CHANGED LIGHTS TO RECEIVE A SAFE INDICATION.

Narrative: ON LNDG GEAR EXTENSION THE L MAIN INDICATOR SHOWED UNSAFE WITH NO ILLUMINATION. EXECUTED A GENTLE GAR AT APPROX 1000 FT AGL. FLEW IN THE PVD AREA WHILE TROUBLESHOOTING. SWAPPING LIGHT FIXTURES AND BULBS ALLOWED THE CREW TO CONFIRM THE GEAR WAS IN FACT DOWN AND SAFE. NO EMER DECLARED. TWR CALLED OUT EMER EQUIP AND A NORMAL LNDG WAS ACCOMPLISHED. DISPATCH AND MAINT NOTIFIED. NO CABIN PREPARATION OTHER THAN COM OF THE SITUATION TO PAX AND FLT ATTENDANTS.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.