175A Push/Pull Switches

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5 months 2 weeks ago #1829 by Jason Hughes
I finally got around to replacing my master switch with new old stock and it didn't change anything. I still have a slight, rapid oscillation in my ammeter. I'm wondering if it isn't the ammeter at this point. I have a USB outlet in my cigarette lighter and it doesn't flucuate the volts, but I realize that is comparing apples to oranges.

Does anyone have any other suggestions on what to look at? I've changed the voltage regulator (which did help eliminate most of the flucuations), all the wiring associated with it, and the master switch. I've also cleaned the connections at the master relay and battery terminals. Maybe I need to slowly start replacing all the wiring from the master switch to the bus and ammeter. I'm sure that wouldn't hurt anyway as most of the wiring looks original.

Thanks,
Jason

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6 months 3 weeks ago #1770 by STEVE ELLS
Replied by STEVE ELLS on topic 175A Push/Pull Switches
Jason,
Thanks for the update.
S

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6 months 3 weeks ago - 6 months 3 weeks ago #1768 by Jason Hughes
The Corrosion X didn’t help any so I found some used switches at Dawson Aircraft and eBay.

I replaced the landing switch and it works like it should. The replacement has a much stiffer detent than my original one so I imagine the contacts are very worn on the original. I hope the new master takes the slight oscillation out of the ammeter, but I haven’t received that one yet.

Thanks for all the help,
Jason
Last edit: 6 months 3 weeks ago by Jason Hughes.

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6 months 4 weeks ago #1759 by Jason Hughes
Thanks Steve. That was very informative.

I will try the Corrosion X in the switches as I have that on hand. I have found a few used switches online that I will try if the Corrsion X does not work.

I’ll look up the Service Bulletin and decide if I want to go that route if necessary.

Thanks again,
Jason

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7 months 5 hours ago #1755 by STEVE ELLS
Replied by STEVE ELLS on topic 175A Push/Pull Switches
Hey Jason;
The short answer is that replacement switches have to be the same ones that were in that model airplane when it was sold by Cessna. R & R in the original type switches requires no additional approval.
Switching to different switches require some kind of approval. The approval can be in the form of a Supplemental Type Certificate (STC) which is a FAA approved addition to the original aircraft Type Certificate, or replacement switches can be approved through what's called a Parts Manufacturing Approval (PMA). Replacement switches that have been built in accordance with the specifications in a Technical Standard Order (TSO) may also be installed and the only approval that's required is a log book entry
You can get more information on approvals in this article written by Kristin Winter, a writer for Piper Flyer. www.cessnaflyer.org/maintenance-tech/ite...nd-applications.html .
The part numbers for the master is 0713026-5; the nav light switch is 0713026-4, and the landing light is 0713035.
Cessna issued Single Engine Service Bulletin SEB 93-15 which provided part numbers for service kits to replace your original push pull switches. These kits seem to still be available. Cost ranges from $62 to $126 per kit.
If you switches aren't working well, you should try to revive them by spraying a contact cleaner/lubricant into the switch and working it in and out. One product that does a good job of this is Corrosion X, which can be purchased at aviation supply houses such as Aircraft Spruce and Specialty ( www.aircraftspruce.com ).
You can also find used original style switches at aircraft salvage yard such as Wentworth and Preferred Air Parts.
Try refurbing your existing switches; if one if broken or inop, you'll be able to find a used one at a salvage yard. I believe all salvage yards offer a money back no questions asked guarantee on parts if returned promptly.
Keep in touch and let me know how this works out
Steve
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7 months 1 day ago #1754 by Andrew Reed
Replied by Andrew Reed on topic 175A Push/Pull Switches
Aircraft Spruce or Edmo should be able to hook you up

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