So it is my first night flight, IFR, raining, getting ready to land. Drop the gear and no gear down light.

 

Fortunately, on the pre-inspection we had no gear down light as well but discovered the Nav lights were on and since it was daylight was told we just couldn't see it since with the Nav lights on it is dimmed.

While it is not dimmed, it simply isn't there when the Nav lights are turned on. The amber light does dim but is clearly visible at night. Lesson 1 - Do a pre-inspection at night as well as in the daylight.

I only have an single amber up light and a single green down and locked light. With Nav lights off it is a nice bright green.

Any ideas? There aren't two separate bulbs in the single display is there? I did rotate the indicator with no luck.

Wish this was the only problem I have with this plane but alas, this is the most minor of problems but I sure would like that warm fuzzy of a green light at night without having to turn off my Navs to get it.

I believe there is a 330 ohm resistor in the dimmer switch. I changed to a higher value on mine many years ago and it fixed the problem. It's a little hard to get to for an old man.

 

Richard Doehring

Richard, what you describe is similar to an intermittent green gear light or slow to come on - at times we could fix it by turning the panel lights on and off. The fix for us was replacing the nose gear micro-swtich. If this is where you get to - e sure to have the mechanic follow every single gear adjustment line item in the service manual. If they do not, you get a false-positive green gear light and the gear will collapse upon landing.

I don't think it is the limit switch. The gear down indication works fine with the nav lights off.

 

The amber light is very dim when the nav lights are on but at least I can see it.

... then I'd go for good grounds and connections as next step in problem determination ... mechanics may have other advice.

Mine acted just like you described. With the nav lights on,if you looked VERY closely you could see just a glimmer of green. With them off, it was a bright green light. I put in a new panel and now the problem is gone.

 

I always thought that the "nav lights on" just sent too weak of a signal to the down light, so part of my night GUMP check included toggling the nav switch to confirm a bright green.

Gear down light saga continues. Departing IFR at night I failed to get a gear up indication. I cycled the gear to no avail. Since I was aware of the gear down anomaly with the nav lights I decided to turn off the nav lights and lo and behold, I got a gear up indication. So now whenever the nav lights are on I do not get a gear up or gear down indication. Before, the nav lights only affected the gear down indication. The gear up was quite visible with the nav lights on.

 

Now I am not sure if they are related but at the same time I lost my gear up indication I also lost my rotating beacon. I can't see where these would be connected but I also don't believe in coincidences. Whether the rotating beacon switch is on or not the gear up light still does not come on.

On landing I checked all my nav lights and they were working fine.

I purchased a set of Orion strobes/navs so once I get them installed maybe all of this will correct itself.

Probably a problem with the wiring or ground on the gear indicator lights. Do yourself a favor, and get Matt Kurke's kit (ComancheGear.com) and replace the gear indicator lights with the iris type lights that you can individually adjust. That will take the nav light dimmer feature out of the circuit and have the added benefit of cleaning up the wiring.

Richard - had similar problems - the change in lights changed amps enough to force the nose gear micro switch into working a ta-da - what ever wasn't working did. - the ultimate fix was replacing the nose gear micro switch

 

Again, Matt would be my 1st choice for help.

I have been told there is a resistor in the nav light switch that might have gone bad. I am going to focus on that. Strange that it only affected the gear down light until recently.

 

I actually think I might already have the iris gear indicators. I know that I can twist them to change their intensity.

So much to learn. Hopefully I can make a fly in soon to meet fellow Comanche pilots and really learn this plane. I have read the entire Tips publication. Didn't sleep for a week after that.

Some day my wish list is going to be bigger than my squawk list.

Richard,
If you have the twist to dim, push to test lights already, I would suggest you remove the resister entirely from the circuit and hard wire the lights to power. You can dim them as needed individually, and the nav lights will not make a difference in the circuit, thus eliminating a current squawk! Matt Kurke would again be the guy to talk to.

 

-Zach

Related post:

 

I just changed my incandescent bulbs in the gear position lamps to LED's. Had a bulb failure several years ago in the green (gear down) lamp that caused momentary angst until I changed to a working bulb, scavenged from the 'in-transit' lamp.
So wanting a lamp with a 10,000 hr. LED, I just slipped the new ones in and they work fine, Except: they don't dim with the panel lights/Nav lights turned on. I suppose they take so little voltage to power the LED, they just remain at their bright level when the incandescent bulbs would dim.

I'm not doing as much night flying as in the past, so maybe this won't be too distracting. Anyone else had this experience?

Sam,

 

LED's don't dim like incandescent lamps. If you switch to the Mil Spec press-to-test, shutter type fixtures, you will be able to dim as it does so mechanically, not electrically.

Interestingly, I have the shutter type gear indication lights. Not sure why they are tied into the Navigation dimmer switch.

Because the installer didn't think things through and realize that you don't need the dimming feature any more.