Switches

[Aussie_1]

The old piano key switches in my 1950 C170a are starting to become very unreliable, the latest problem is that the landing and taxi lights now turn themselves off after a minute or two.

So I am considering replacing the whole switch panel with some new switches. Has anybody done this, if so do you have any pictures of what you have done or what switches you used, or how you went about it.

Aslo I'm sure there is probably some information in one of the forums on this subject so it would be appreciated if you could point me to the right place.

Any advice would be appreciated.

[Bruce Fenstermacher]

First you should know that the switches behind the "piano keys" are regular AN switches that can easily be bought. AN-3027-1 for the master and AN-3021-1 for the other stock switches and probably any that were added after. Replacing them isn't so easy but not impossible.

Piano key switch assembly.png

034.jpg

The problem is the switches and fuse holders (assuming original) and the wire bundle going between them and out to the rest of the plane are pretty tight and you nearly have to disassemble and remove the fuse holding bracket, the switch bracket and the wire bundle in order to separate them enough to work on any of it. It can be done, I've done it. Just get comfortable under the panel with good light, a few pair of bifocals at different strengths, and someone outside the plane to hand you tools so you don't have to crawl in and out of the plane.

A problem with the early Piano Key design panel is there isn't a lot of space for the most part. One either has radios on either side with or without the false panel from or they have radios and glove compartment. The four smaller gauges are held in place by a panel and the whole thing is covered with the Plexi. Pretty hard to add much or move things around. I'm not sure you could find a better place for the switches without a complete panel replacement and now your getting in to lots of work. Better to bit the bullet maybe and replace the switches where they are.

[bagarre]

I'll have to dig around but, I might have photos from when I replaced all my switches a year or so ago.

In my case, I had all the original wires so I opted to re-wire the entire panel and put in breakers. If you are going to replace the switches, go ahead and replace as many wires as you can. It really isn't that much more work.

To remove the piano keys assembly without taking EVERYTHING apart, there is a trick. Two lower bolts that hold the assembly in are behind the plexi. Two well placed 3/16th holes in the plexi get you access to the screw heads. This will knock a day's work off the job.

Search the forum, there are a lot of good threads about these keys and all the wires back there.

[KS170A]

A simple fuse replacement on my airplane evolved into a very large project that included "switching" to circuit breakers (sorry, couldn't resist), replacing a couple of the switches, and replacing all of the 1950-vintage wiring. Here are a couple photos of the switch assembly removed.

switch assy top.jpg

switch assy back.jpg

Sw Panel New Sw CBs.jpg

Here's what my panel looked like just after starting (I did have an overlay over the shock panel).

Old Panel.jpg

Here's what it looks like today.

New Panel.jpg

[GAHorn]

Very nice post (and work product), Josh!

Is that Vodka? or Gin in that glass?



(Used for cleaning purposes on the switch panel, I presume?)

[KS170A]

Very nice post (and work product), Josh!

Is that Vodka? or Gin in that glass?

(Used for cleaning purposes on the switch panel, I presume?)

Thanks, George! Vodka...for cleaning, of course! OK, maybe some post-mtx relaxation, too...

[GAHorn]

Yeah....I figgured as much.

Either that,.... or First Aid antiseptic to treat the wounds-and-scratches on the back of your hands!

[Aussie_1]

Thanks for the help guys. It's obviously time to get in with a pillow, torch and a bunch of tools to fix things.