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  #1  
Old 06-08-2018, 05:16 PM
JDA_BTR JDA_BTR is offline
 
Join Date: Dec 2013
Location: Baton Rouge, LA
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Default Firewall penetration question

With the fm150 should all the cables come through the middle penetration? Or does the governor go through the left? Or?

Do the cylinder and egt temp lines run best thru middle or left? Same question for red cube? My GEA24 is on the left sub-panel
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  #2  
Old 06-08-2018, 06:03 PM
Mark33 Mark33 is offline
 
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  #3  
Old 06-09-2018, 01:59 AM
JHartline JHartline is offline
 
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Location: Carrollton, GA 5GA2
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I routed the control cables as depicted in the plans. Using the mounting bracket from Airflow the cable lengths are correct. See a related thread about how to mount the bracket if you havenít done that part yet.

My GEA24 is on the right subpanel. I split the EGT & CHT into two bundles, motor right and left, and ran them through the openings on their respective sides. I would think thereís plenty of wire length to do it however it works best for you. I believe I ran my fuel flow wire through the left side.
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Old 11-08-2018, 09:51 PM
JDA_BTR JDA_BTR is offline
 
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Iím going to put in another firewall penetration using the Avery kit. I was planning to put it above or below the fuel and oil pressure block and a little left.

Is there a reason not to put a penetration higher on the top part of the firewall or is lower better? Might put it in the space behind where the left top engine mount tubes come together. 14a.
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  #5  
Old 11-09-2018, 06:22 AM
Tom023 Tom023 is offline
 
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I did a combination of the previous responses. I ran control cables as plans and also have the FM150. Split engine left and right and used both pass throughs. I added a 1/2” third pass through below the upper left engine mount specifically for power cables.
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Last edited by Tom023 : 11-09-2018 at 08:50 AM.
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  #6  
Old 11-09-2018, 07:41 AM
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DanH DanH is offline
 
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May I add a note here?

A tubular steel firewall pass-through filled with an intumescent sealant is very fire resistant. The sealant will also do a pretty good job of locking the components (wires, cables, etc) in relation to each other. However, that fixation is not perfect, as the sealant is elastic. It's also easy to have voids inside the tube, since flow during sealant injection is entirely random.

I've seen a few -14's with power wires, control/instrument wires, and engine push-pull cables all run through the same tube. Must be on the plans that way. This one is typical.

I think it's a bad idea.



First, the fundamental objection; Bowden cables can act like a saw. I've seen 'em cut completely through an Adel clamp. It doesn't take a lot of mis-rigging to have that Bowden pull a little with each startup, for example.

Second, note the approach angle on the big wire. It is hard against the edge of the tube at 1:00 o'clock. It will wear through the insulation there even if the tube is full of sealant.

Third, think about maintenance, or wiring changes in the future. The big control push-pull will wear out eventually. It will need to be removed through the tube, and a new push-pull inserted. If you install the push-pull with its end fittings, then install wires, will you have enough clearance to get it back out without first removing the wires?

Last, clearance issues aside, the sealant plug will need to be cut away from the interior surface of the tube in order to remove wires or cables. To do it requires using a shop-made semicircular "knife" pushed into the tube in two or three places. Here there is no clearance for the approach of the knife. The cables need to come straight out of the fitting for at least an inch or two.

I realize locating firewall passages is a challenge for some builders, so I'm not going to tell you where to put them. If you want to stick with the location(s) on the plans, that's great. However, I strongly recommend that you install separate pass-throughs for control cables and wires. It need not be complicated. Using the above as an example, just put two of them side by side. I'm sure Vans will cheerfully sell you a few more, and they're easy to weld up locally. If you wish, weld multiple tubes on the same baseplate to save real estate.
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