Amber light failure: The amber light is the landing gear gear-up indicator light.


With the gear down, check both terminals of the amber indicator for power and ground with lens removed. That would be the center pin and the [threaded] case. Also keep in mind that this style indicator uses insulators between the case and the panel, otherwise it will/may inadvertently be grounded [strong hint].

In the attached I have highlighted the green and amber circuits. Follow the amber track and you may find an errant source for a ground. During normal operation the amber grounds through the up-limit switch which you have already replaced. The green line is ground for the green light; the amber line is ground for the amber light. See the legend in the attached for the power sources.

You’ll also see the amber’s voltage supply is throttle-dependent; this is actually the intermittent application of power which I’ll call “groundus interruptus”, i.e. the flasher function. Move each throttle and note any change; that could be another clue but less likely.

In this failure mode the alternate voltage source, and the green light’s source, is the instrument light rheostat. Additionally it is doubtful the flasher has anything to do with this behavior.

Hint – my PTT – light kit requires no insulators.

– Matt

Attach fig 11-70 amber green red

Figure 11-70a Comanche Landing Gear-Up Amber Light Failure