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OK, this may be a silly question, but how are you supposed to test the gear down indicator lights in a '77 Lance? The three green lights?
Reason I am asking is I bought an old lance and brought it to AZ for a little TLC before putting it to work up in AK. This is an old freight dog that has seen its share of service and then some. I have been going thru it getting it ready to go, pull the gear and re-bush/re-build as necessary, new avionics, fix a weeping fuel tank and so on.
One of the things I noticed when I flew it down, other than the fact the gear wouldn't retract, (bad o-ring) was the gear lights were a bit funky, you had to fiddle with them occasionally to get three green. One issue I found was a grumpy micro-switch on the nose gear; simple enough. But when I was lying on my back yarding our decades of old crappy wiring I noticed a rat nest of butt-splices adorned the back of the gear indicator lights. Maybe that has something to do with the intermittent gear light issue?
After attacking the indicator lights with a pair of wire cutters and extracting the mess from behind the panel I noticed there are only two wires going to each lamp instead of the normal three I am accustomed to seeing on the back of regular push-to-test indicator lamps. Maybe that's is why pushing on them did little to nothing?? A look at the electrical schematic confirmed there are only two wires attached to each light, a switched hot from the gear switches and a ground, with a resistor if the lights are on for dimming that completes the circuit. My only other thought was it may be part of the test circuit for the engine annunciators, but if it is I can find nothing in the book that depicts that circuit.
Am I missing something, or is there really no way to test for a faulty bulb other than just swap them around? I figured it would be in the POH, or at least in the maintenance manual, but if it is I didn't find it. Perhaps I just missed it (a distinct possibility).
Thanks,
Jeff
Reason I am asking is I bought an old lance and brought it to AZ for a little TLC before putting it to work up in AK. This is an old freight dog that has seen its share of service and then some. I have been going thru it getting it ready to go, pull the gear and re-bush/re-build as necessary, new avionics, fix a weeping fuel tank and so on.
One of the things I noticed when I flew it down, other than the fact the gear wouldn't retract, (bad o-ring) was the gear lights were a bit funky, you had to fiddle with them occasionally to get three green. One issue I found was a grumpy micro-switch on the nose gear; simple enough. But when I was lying on my back yarding our decades of old crappy wiring I noticed a rat nest of butt-splices adorned the back of the gear indicator lights. Maybe that has something to do with the intermittent gear light issue?
After attacking the indicator lights with a pair of wire cutters and extracting the mess from behind the panel I noticed there are only two wires going to each lamp instead of the normal three I am accustomed to seeing on the back of regular push-to-test indicator lamps. Maybe that's is why pushing on them did little to nothing?? A look at the electrical schematic confirmed there are only two wires attached to each light, a switched hot from the gear switches and a ground, with a resistor if the lights are on for dimming that completes the circuit. My only other thought was it may be part of the test circuit for the engine annunciators, but if it is I can find nothing in the book that depicts that circuit.
Am I missing something, or is there really no way to test for a faulty bulb other than just swap them around? I figured it would be in the POH, or at least in the maintenance manual, but if it is I didn't find it. Perhaps I just missed it (a distinct possibility).
Thanks,
Jeff
