MD-83
Flight Crew Air Transport Pilot (ATP)
Confusion; Troubleshooting; Training / Qualification; Human-Machine Interface
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Aircraft Equipment Problem Dissipated; Flight Crew Took Evasive Action; Flight Crew Executed Go Around / Missed Approach; General Maintenance Action
Procedure; Manuals; Aircraft
Upon gear extension during a visual approach to Runway 18; the left main gear green light failed to illuminate. There was no red gear unsafe light; and a quick light bulb test verified that both light bulbs in the gear down cartridge had failed. We initiated a go-around; and the First Officer extracted one bulb from the gear unsafe light cartridge; and installed it in the gear down light cartridge. We executed another bulb test; verified that all six gear lights were functioning; and then executed a second visual approach; landing normally. We did not declare an emergency; and we wrote up the bulb failures in the aircraft logbook. The issue that I want to point out has to do with the QRH. There is no procedure for replacing a gear down indication light bulb in the QRH. As far as I can find; there is no authorization anywhere for a pilot to replace a light bulb under any circumstances. In that respect; replacing the bulb becomes a utilization of the Captain's emergency authority. At the time; I did not consider this.Gear down indication failures happen. A quick review of the FAA SDR data shows that they happen relatively often; and that the standard response is to swap bulbs; cartridges; etc. in order to obtain a safe gear indication. However; the QRH preface is clear that all non-normal procedures are contained within the QRH. A bulb changing procedure is not contained in the QRH. There are two reasons to re-consider this situation: first; simple things like changing light bulbs can have huge unintended consequences in some designs; i.e.; cartridge springs popping out; improper re-seating of the cartridge causing a short; etc. Second; in order to obtain compliance with the QRH philosophy regarding non-normals; 'routine' or foreseeable problems like the gear down indication need to be included; even if it is a simple procedure that says; 'change the bulb'.
A MD-80 Captain reported that after the landing gear extension the left main gear had no indication so the First Officer tested the bulbs to discover them inoperative so they were changed. There was no authorization to change any bulb.