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Advice on Control Cables Through irewall

rvanstory

Well Known Member
Really struggling with making a decision regarding the control cable pass throughs the firewall. I followed the plans earlier and have three 5/8" holes for the cables. But, plans also call for standard plastic grommets. I prefer more fire protection than that.

Many of the posts are using the Doubletree firewall passthroughs. http://www.doubleteeproducts.com/ But the dimensions don't work with the existing holes.

Looking at this unit from ACS as I can cut out the holes and position them where I want.
https://www.aircraftspruce.com/catalog/appages/sptfirwallkit.php

Looking for advice from someone that used the Van's holes (5/8") to start and achieved better fire protection than standard plastic grommets.
 
You should call Doubletree and ask them if there is enough material for you to drill them out. I needed a slightly larger diameter and was going to order a custom hole size. They told me to just drill out the center hole.

As an alternative you could just make a SS patch with the grommets you want and then cutout the area with the existing holes. Seal it up an rivet it on with SS blind rivets.
 
advice

Looking for advice from someone that used the Van's holes (5/8") to start and achieved better fire protection than standard plastic grommets.
My advice is to avoid the round aluminum ones, and go with the screw-on steel model.

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I like those too, but the largest size hole is .260. I'm using a center console throttle quadrant and the longer cables I purchased are .334 wide. So, the center hole is too small.

hmmm.. so am I.
although I haven't purchased cables yet. sounds like I might need to revisit this choice too once I'm a little further along...
 
I needed a slightly larger diameter and was going to order a custom hole size.

Same for me. They are easy to drill out and get the exact size you need. I ordered several with small holes and custom fit them to each cable.

I went with the 4200 series Doubletee. They come in the size you need.

These are the ones I use and would do the same again.
 
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My holes were smaller, as I only drilled to what was necessary to get the cable through. I then made two 1/4" aluminum bars a bit longer than the length of the cable outlet area and about 3/8" wide. Place the two together and drill tap two holes width wise for #6 screws. Assemble and then drill your four cable holes, centered exactly on the seam (drill bit very close to the cable OD). Drill four holes on the corners for securing to f/w with #6 screws. I avoided rivets for this, as I thought they would be hard to drill out once the engine is in.

It is cheap, easy to make and removeable for maintenance. Yes, fire could melt through 1/4" AL, but will take a LOT of heat to do so and is MUCH better than plastic grommets.

You could make a similar design with overlapping sheets of thin SS instead of butting together thick al. Key is clamping it up before drilling hole to keep your alignment. This approach would require some type of chafe protection though that the 1/4 bar approach does not.

I have more time than money, so tend to go this route versus buying COS products.

Larry
 
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hmmm.. so am I.
although I haven't purchased cables yet. sounds like I might need to revisit this choice too once I'm a little further along...

I did use the TTP 6100 fittings with .26" ball on my RV-10 in the pre-drilled locations. They are a little tricky to get safety wired as they are so close together, but work fine with the standard VANs cables.

I want to point out that the cable fittings at the engine end are bigger than the sheathed portion of the cable. These fittings just barely fit through the TTP 6100 with the ball removed.

You may be able to to remove a small section of the sheathing at the ball to reduce the diameter assuming the end of the cable fits.
 
Same for me. They are easy to drill out and get the exact size you need. I ordered several with small holes and custom fit them to each cable.

These are the ones I use and would do the same again.

Larry, I live in New Braunfels too. Would it be possible to come see your installation?
 
Yer' makin' it too hard.

We can both agree on that statement!!! Seems at this stage of the build without Van's specifically calling out every rivet and every hole that I am making it much harder than it needs to be. :)
 
That's typical Randy, so don't feel bad about it. Most new builders figure they successfully ate the elephant when the airframe is done. Then they begin to install systems...

The interesting thing about the fabricated tubular pass-through (beside being economical and any desired diameter) is that the injected FireBarrier 2000 fixates the control cable very well.

BTW, sealants, grommets, and the tube-type pass-through all literally catch **** starting at post #40:

http://www.vansairforce.com/community/showthread.php?t=72087&page=4
 
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Dan, Is it OK to sandwich the fiberfrax along with the stainless foil under the items being bolted to the firewall or is it better to cut the fiberfrax around each component so it's just the stainless under them?
 
Dan, Is it OK to sandwich the fiberfrax along with the stainless foil under the items being bolted to the firewall or is it better to cut the fiberfrax around each component so it's just the stainless under them?

Fine to sandwich the SS foil and fiberfrax under non-structural things, like the pass-thrus, or battery boxes, or solenoids. You must not sandwich under structure, notably the motor mount attach points.
 
Fine to sandwich the SS foil and fiberfrax under non-structural things, like the pass-thrus, or battery boxes, or solenoids. You must not sandwich under structure, notably the motor mount attach points.

Excellent. Thank you. I knew about the motor mount but hadn't seen any details on other items on the firewall.
 
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