Landing & Taxi Light Switch

[170C]

I just noticed that my landing light wasn't coming on when the switch was pulled out all the way. Although the bulb appeared OK, I exchanged it for a new one. Guess what---the new bulb didn't light up either. Checked for power to the bulb (should have done this first ) and no power. Went back and operated the switch a couple of times and found that if I pulled on the switch knob a bit harder that the landing light came on. So I have an issue with my switch. Would spraying contact cleaner in the switch be a possible solution? Also have noticed the nav light switch is harder to pull on than it used to be. Would the same contact cleaner possibly correct this?

[Onewinglo]

If you do decide to try contact cleaner be sure it is "Plastic Safe". I bought some years ago that was not safe for plastics and ruined a couple switches. The plastic partially dissolved and welded itself together.
The good news is the switches were in a 1955 Seeburg JL jukebox and were easily sourced, cheap and easy to replace. Not sure if any of that applies to our airplanes...
Good luck!
JP

[edbooth]

I just noticed that my landing light wasn't coming on when the switch was pulled out all the way. Although the bulb appeared OK, I exchanged it for a new one. Guess what---the new bulb didn't light up either. Checked for power to the bulb (should have done this first ) and no power. Went back and operated the switch a couple of times and found that if I pulled on the switch knob a bit harder that the landing light came on. So I have an issue with my switch. Would spraying contact cleaner in the switch be a possible solution? Also have noticed the nav light switch is harder to pull on than it used to be. Would the same contact cleaner possibly correct this?

Frank , if you have the same type as used on the 53 and up 170's, the rectangular one with the phonelic piece on
top held together with four little tabs, you can carefully pry those tabs open, pull the top off and check to see if anything is broken or burned. If all looks ok, clean the contacts, put a little lub on them and put it back together. It's a pretty robust switch.

[170C]

Thanks for the suggestion Ed. I don't remember exactly what the late model 170's have for nav, taxi & landing light switches. Mine are just small, round pull switches and I haven't contorted myself up under the instrument panel yet to see what they look like, but will do so. These old 58 year old switches just don't last

[daedaluscan]

My master became intermittent, and I replaced it with a used one. The new price was nearly $300 I think.

You can take them apart by bending the tangs on the back and then cleaning, but mine had a broken insulating sheet inside.

Pretty sure that these are a standard automotive/truck/boat switch, I just never succeeded sourcing one outside Cessna.

[GAHorn]

Frank, what you describe is virtually the same problem I had 10 years ago with my Master switch.

I removed the plastic knob (unscrew it) and remove the lock-nut on the switch...remove the wires from the switch and pull the switch out of the panel.
Using needle-nosed pliers and a flat screwdriver, pry up the four little tabs and disassemble the switch...(be careful for small parts and springs) and use emery or sandpaper clean the contacts. You can even build them up a bit with solder if you're bold, but it's not likely necessary.
Use a little dab of white lithium grease, and reassemble and reinstall.

These same switches are available thru NAPA auto parts, but I don't have the electrics catalog with me right now in DFW. They are less than $20 and exact replacements. (They come in single and dual circuit, also DPDT versions.) The particular one depicted is their PN: SME MP39520

NWMDC.jpg

I also have a few used spares in my junk box should you get really overburdened with problems and need to drown the switchology-sorry over a beer next convention.

SAVE those knobs tho'.... those are the hard-to-find parts...and they screw onto the NAPA part.

[170C]

Thanks George. I forgot to ask about this when you called me yesterday. This sounds like a project for tomorrow, weather (temp) permitting.

Frank