Vacuum Air Filter

How to keep the Cessna 170 flying and airworthy.

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nippaero
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Vacuum Air Filter

Post by nippaero »

Just hooked up my Vacuum system again after having my DG overhauled. I only have one instrument on the vacuum system. Does anyone make a small air filter that can be attached directly to the back of the air intake on the DG?
1952 170B
N8180A s/n 25032
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GAHorn
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Re: Vacuum Air Filter

Post by GAHorn »

The AN gyros had pancake/flat filters incorporated on their cases... but they aren't particularly "sturdy" in the sense they won't hold much dirt if you're in a dusty environ. It should be easy to use a short piece of vacuum hose with a "nipple" and attach a canister filter such as the Rapco Model RA2J4-4

http://www.aircraftspruce.com/catalog/i ... key=280803

Nipple: http://www.aircraftspruce.com/catalog/h ... ckkey=5344
'53 B-model N146YS SN:25713
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Bruce Fenstermacher
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Re: Vacuum Air Filter

Post by Bruce Fenstermacher »

And of course as you will only have one line you must plug the unused line on the filter George mentioned.
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nippaero
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Re: Vacuum Air Filter

Post by nippaero »

Thanks guys. I have the Rapco filter. I was just wondering if anyone has ever seen something smaller that could screw in where the nipple goes. I imagined something similar to this
https://www.grainger.com/product/SPEEDA ... Vent-1EJT6
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1EJT5_AS02.jpg
1952 170B
N8180A s/n 25032
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n2582d
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Re: Vacuum Air Filter

Post by n2582d »

Mike, As George said each instrument had it's own internal filter. Amazingly, although the prices have increased a bit, these filters are still available online. Here's a SNL with some part numbers:
Click to Enlarge
Click to Enlarge
I'm curious which Rapco filter you are using as Cessna mounted these differently over the years. As you have a DG and an attitude indicator it seems that the two port filter would work best for your application. Personally I'd stick with the Rapco filter as I think it would filter better than an inline filter like you pictured. It'd be a lot easier to replace as well.
Edit:
I only have one instrument on the vacuum system
In an earlier post with a picture of your panel you had an attitude indicator. Did you remove that?
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n3833v
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Re: Vacuum Air Filter

Post by n3833v »

Your little screen filter looks like a Cummins fuel system filter for the fuel pump aneroid intake system [1/8" pipe].

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GAHorn
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Re: Vacuum Air Filter

Post by GAHorn »

The small metallic filter depicted above will not have much media-capacity for an air filter. That sort of filter is designed to catch large particles in a suction "pick-up" tube or such.... it cannot contain much dust/dirt which is what you need... if you want that gyro to last very long. I recommend you use an ordinary gyro filter such as suggested previously.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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nippaero
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Re: Vacuum Air Filter

Post by nippaero »

Thanks George. I did install my Rapco filter back on there. Thanks everyone!
1952 170B
N8180A s/n 25032
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