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Firewall pass throughs

claycookiemonster

Well Known Member
The general rule of thumb is to gather power in one corner, and sensors on another. Fine.
What about linkages? What sort of fitting for those three holes for the throttle/mixture/prop? It seems they must be separate? Can the oil cooler valve and alternate air linkages be grouped, or should they be separate too?
Are the firewall fittings the same for wiring as for moving cables linkages?
 
Cables

The general rule of thumb is to gather power in one corner, and sensors on another. Fine.
What about linkages? What sort of fitting for those three holes for the throttle/mixture/prop? It seems they must be separate? Can the oil cooler valve and alternate air linkages be grouped, or should they be separate too?
Are the firewall fittings the same for wiring as for moving cables linkages?

I used eyeball pass through for the big three. Aircraft Spruce.
Bowden cables went through these.
https://drive.google.com/file/d/1tB21mLWEKjV88yrpE24svFCn_n4nf9-V/view?usp=share_link
 
These are speedy but nice

https://www.aircraftspruce.com/catalog/appages/eyeballfw2.php?clickkey=6551

If you own a lathe, you can do what I did:

Drill an appropriately sized hole through the center of a stainless fine thread bolt and machine a taper on the last few threads. Cut slots in the bolt with a hacksaw, dremel cutoff disc, or similar. Then get some hex stock and drill and tap a hole in the middle to match the threads on the bolt, use a plug tap and don’t cut threads completely through. Drill small 1/16” holes in the hex for safety wire if you so choose. The taper of the female threads squeezes on the taper of the male threads and holds the Bowden cable very securely with little torque. Cheap and light.
 
For engine control cables I use this (3/8” cable): https://www.aircraftspruce.com/catalog/appages/cablesafe2.php?clickkey=32894

For wires, cabin heat and oil cooler control cables I use two of the nice RV-14 SS firewall penetrators. The inside of the penetrator has a lining of firesleeve. Any control cables are first covered with tubing to mitigate wear agains wiring. The entire bundle then has a piece of firesleeve that goes over the bundle and the outside of the penetration flange.

Carl
 
Doubletree Products

For Control cables I used the steel, single hole version from Doubletree Products (pictured).

For wires, power, sensor, etc. I used 3/4" EMT connectors (minus the set screw)
 

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