The International Cessna 170 Association

My landing/taxi light switch has gotten to where sometimes the taxi light and/or landing light come on when the switch is pulled out (on) and other times it/they don't. If I turn it off and pull it on again it usually comes on, but the same issue repeats itself the next time. Is there some type of spray that can be used on the switch to fix this or is my switch shot? If the latter, what is the replacement part # and a good source? ('56 172)

I have successfully cleaned some of my switches with CRC Lectra-Motive Electric Parts Cleaner. I think I bought it at NAPA. It hasn't failed me yet. Some switches are easier than others to get the spray inside the switch, but usually I am able to do it.

If it has not been done before you can open these switches. Not that I would recommend that of course.

These little pull-switches are nothing more than a metal can with bent-over tabs that can be opened up and cleaned. There's a sliding phenolic plate with contacts on it that make the connections with the terminals. I've successfully repaired them by cleaning and lubricating with electric-contact grease, then reassembling them. Some of them might also contain a small spring that needs "repair" to maintain good contact.

gahorn wrote:These little pull-switches are nothing more than a metal can with bent-over tabs that can be opened up and cleaned. There's a sliding phenolic plate with contacts on it that make the connections with the terminals. I've successfully repaired them by cleaning and lubricating with electric-contact grease, then reassembling them. Some of them might also contain a small spring that needs "repair" to maintain good contact.

Yep, what George says.....

Thanks for the replies guys. Two possible solutions. Regarding the electric contact grease, is that the same stuff you can use on the base of automotive/aircraft light bulbs to help make contact and keep out moisture?

I have switches 715 823 6702

That would certainly work, Frank.... (Dow Corning DC4, dielectric silicone grease).

Thanks. A tube of DC-4 will last several lifetimes!

Just to be clear.... simply adding grease will not likely fix the problem.... it will only extend the life of the switch after the problem is fixed.... by cleaning the contact surfaces with a rubber eraser or lightly hitting it with emery, etc., and checking the spring (if any).

I once took off in the early Saturday AM on a pancake-mission and after several minutes at cruise I happened to notice my generator was not "genning"... ... I pulled a little harder on/and wiggled the Master Switch knob .... (remembering the Master Switch on the panel carries TWO circuits... one grounds-out the battery-solenoid/relay on the batt-box to activate it and put battery-power onto the electrical-buss.... and the second circuit connects the generator FIELD terminal to the regulator FIELD terminal.) Wiggling it made the connection and my generator came on-line.

This was what compelled me to disassemble that switch, clean the contacts, and grease the switch. It's been working now for an additional 14 years very satisfactorily.