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Bowden Cable Firewall Pass Thru

wirejock

Well Known Member
I can't take credit for this. Dan Langhout posted it back in 2011 but I can't find it. Thank goodness I saved a pdf copy.

These are the fittings I found worked best.
Aluminum will certainly work. Lighter and cheaper but steel fittings are recommended FWF and the wholenidea is a fireproof penetration. You may consider some 3M 2000 inside the fitting before locking it down. The cable in the photo is actually passing through backwards. You'll figure it out.

AN819-4 AN FITTING
AN832-4 STEEL FLARED UNION
AN818-4 STEEL NUT
AN924-4 Steel AN Fitting
3/16" or 1/4" Brass Ferrule
Stainless washers
I bought stainless washers and used a step drill to increase the hole diameter. 7/16" for AN4 fittings.

Measure your cable first.
The smaller push-pull Bowden cable...
Drill the fitting with a #13 drill then a #12 reamer. Use the 3/16" ferrule.
Larger Bowden cable, use the 1/4" ferrule
20210227_134115.jpg
 
Or go to hardware store, buy a bolt large enough to drill a 3/16 hole through plus a couple washers and nut. Same idea but much cheaper. Learned that from Sport Aviation magazine.
 
That looks great but I'm so tired of being nickel and dime to death with shipping.

I'm buying this compression union from my local hardware store and calling it good.

EAA video on using this compression union. (need EAA login to view)
 
Great idea Larry! I like it. Squirt some high temp goop in there and you’re done. I have the stuff that DanH recommended for firewall sealing on hand (2,000* +) and that should keep me safe.
 
Nickel and dime

Love how we nickle and dime on a Firewall Pass Thru then blow $30K on an engine. :D
 
the REAL cost of building an airplane...

When I was thinking about building an airplane, I read that you'll spend 1/3 on the engine, 1/3 on the avionics, and 1/3 on the airframe. What they didn't say was I would spend another 1/3 on tools and another 1/3 on shipping...
 
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When I was thinking about building an airplane, I read that you'll spend 1/3 on the engine, 1/3 on the avionics, and 1/3 on the airframe. What they didn't say was I would spend another 1/3 on tools and another 1/3 on shipping...

I KNOW! I thought I had tools until I started my -14A. $9000 later.....

It's OK, though. The plane is just an excuse to get more cool tools.
 
Separate Firewall Penetrations for Control Cables

So, I gather you guys didn't run the control cables through the same firewall penetrations as the wires? I wonder why the plans have us do that. Seems like separate pass-throughs would be better.
 
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