Date: 201410
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: MD-83
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class C ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Landing Gear Indicating System
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Human-Machine Interface; Troubleshooting
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Executed Go Around / Missed Approach; Flight Crew Landed in Emergency Condition; General Declared Emergency; General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: 2 green 1 blank After selecting gear down; we had a green left main and a green nose gear indication. Noting the lack of a right main gear light; we pressed the bulb check. The red section of the right main indicator illuminated; but not the green section. This suggested that both bulbs in the green section may have burned out. We went around in order to troubleshoot. Since I didn't know the status of the gear yet; I left it down.  We reviewed the QRH and did not find any guidance for this particular scenario. It seemed an easy and quick check to simply remove one of the working light assemblies and put it in the right main gear position. But when we did this; we still did not get a green illumination. We tried both of the other assemblies and neither worked. When we returned the assemblies to their original positions; they no longer showed green. A bulb check showed the red sections still worked. That seemed to suggest that the right main gear circuit had some unknown fault. I wanted to know the status of the right main gear; and wanted more info than what could be observed through the scope which isn't in the QRH. I decided to do a low pass in order to get a visual check of the status of the right main landing gear. I asked my FO what he thought; and he agreed.  We requested that ARFF position a truck with lights at the approach end of the active runway XXR. We asked if the tower would inform [Company] ops as to what was going on. I kept the passengers informed with several PA's during the course of events. After the pass; we were informed that both of the main gear were down. Down; but possibly not locked. I then declared an Emergency as I wanted ARFF standing by should the right main gear buckle. I briefed the flight attendants and covered the TEST items. We advised the tower that we would be stopping on the runway and would need to pin the gear. We also advised [Company] ops that we would need to have the gear pinned while still out on the runway. The landing was gentle and I didn't use a lot of braking. The gear was then pinned and we taxied to the gate without any incident.


Second narrative: We had a landing gear indicator malfunction which required a missed approach followed by a flyby for visual confirmation of the right main gear appearing to be in the down position. We returned for an uneventful landing.


Synopsis: MD-83 flight crew experiences a landing gear indication failure during approach; with two green indications and the right main with no indication. The light test switch indicated the bulbs were burned out and a go-around is initiated to troubleshoot. Bulb assemblies are swapped to the inoperative position but due not indicate green and will not test. Upon returning the bulb assemblies to their original positions they no longer function. After a flyby a normal landing ensues.