What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Firewall Passthrough

JDA_BTR

Well Known Member
I can't find any material in my firewall forward kit to complete my firewall passthroughs. I thought there would be a couple of flat pieces; one to wrap and put into the tube of the passthrough; and a second to wrap over the top of the tube of the passthrough and the first inner layer.

What on the Vans site or ACS is the right material to use for this? How much is needed? Was also going to use the 3M firewall sealant 2000 (3000?) to pot it.
 
+1



Agree. Those work great and when it comes time to replace the worn cables they come apart easily. When I first built my RV I used these:



They were easy to use and looked great. But, when it came time to replace some control cables I found that the finely threaded aluminum parts had galled and they were impossible to dis-assemble without ruining the parts. Don't know why I bought them in the first place as they are 100% aluminum and likely to be the first part of the firewall to burn through in an emergency.
 
what rv7charlie said.elect. dept at any hdwe has connectors to fit a junction box which are perfect for a pass thru.
I had a couple in my last airplane's firewall.someone commented they are a pot metal, not stainless. it was a wooden, cloth covered Dakota hawk, give me abreak!
 
Be careful

Some conduit flanges are galvanized metal. Galvanized metals give off toxic fumes when exposed to high temperatures...
 
Some conduit flanges are galvanized metal. Galvanized metals give off toxic fumes when exposed to high temperatures...

My engine is on fire, fueled by burning avgas, synthetic rubber hoses,oil, plastic insulation, fiberglass, epoxy, paint and a dozen other substances. Am I going to worry about fumes from a galvanized conduit flange? Seriously! :rolleyes: But I do appreciate your comment and concern.
 
Last edited:
Missing the point

Having been around galvanized EMT in high heat situations, I can say that you don?t need a fire for the fumes to occur. Whether or not that temperature can be reached before a fire starts remains to be seen but I can tell you those fumes are dense and noxious. I would never use galvanized EMT on my aircraft, YMMV.

On the other hand, guys are making pass thoughts from SS sheet and thin wall SS tube very inexpensively. Just cut, drill, and weld. Or, mcmaster sells really nice SS flanges, which I used. I did put the flange on the lathe and removed some of the material to make it lighter, though...
 
1. I never said to use galvanized electrical flanges. But I suspect that they are better than a split aluminum ball, as was just listed. Bigger danger is grabbing one of the 'pot metal' items, which have a much lower melting point.

2. https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=Stainless+Steel+Pipe+Tube+Weld+Neck+Flange&_sacat=0
or
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313.TR7.TRC1.A0.H0.Xstainless+grab+bar.TRS0&_nkw=stainless+grab+bar&_sacat=0&LH_TitleDesc=0&_osacat=0&_odkw=Stainless+Steel+Pipe+Tube+Weld+Neck+Flange
if you need two.

3. You guys do know that it's legal to use galvanized steel for the entire firewall, right? And there are hundreds (probably thousands) of classic homebuilts flying with galvanized firewalls? Not saying it's the best solution, but we don't fly turbines, either. ;-)

Charlie

edit: Here's the how-to, on the Aeroelectric site. Note that some of the pics are of FAA-certified factory a/c.
http://www.aeroelectric.com/articles/Tech_Tips/Firewall_Penetration/firewall.html
 
Last edited:
Returning to the OP's question - I had to get a bigger piece of fire sleeve than what was provided in the kit to do the outer "wrap". I had some laying around fortunately.
 
Like others have said, for single cables use the steel multi piece eyeball pass through?s mentioned above. Harder to install but worth it! The single hole aluminum ones are junk!

As for wires/bundles you can get all the parts to build them yourself way cheaper if you buy the parts to make it individually. You can buy the stainless flange from hardware stores or amazon. Look for stainless closet rod holders. They are less than $10 for a pair of them.

I did not do this on my 7 but will on my 10!
 
which size?

I see on Amazon there are different sizes of these stainless rod holders. Is the 1 inch diameter big enough if using 2 of them? I think the other is 1.3 inches inside diameter. Is this like anything else where bigger is better?
 
I had the same concerns about the firewall sleeves and had it confirmed by Vans that we use the FAE102-11x1 ft sleeve they send with firewall forward kit. Apparantly we make that fit for both the inner and outer pass through by splitting that sleeve.
 
How many

I have a large one and a small one. The large one was required to pass the EFII harness connectors through. I separated the EGT/CHT wires to the small one, as was recommended by Garmin.

I now have a System 32 EFII harness which includes bulkhead connectors so I really did not require the large pass through, 2-1" pass throughs would have been sufficient.
 
I see on Amazon there are different sizes of these stainless rod holders. Is the 1 inch diameter big enough if using 2 of them? I think the other is 1.3 inches inside diameter. Is this like anything else where bigger is better?

1st, decide whether you need to pull assembled connectors or control cables through the hole(s). If yes, then the connectors/cable ends will define hole size. Bundle up everything you need to run through each hole, wrap the firesleeve, and measure.

Charlie
 
I am debating adding a few extra pass throughs. An A&P suggested that all the cables go through individual eyeball fittings, then the wires can run through the two original pass thru locations. Anybody do this? If so, then where did you place the eyeball fittings.

I did purchase pass through kits from ACS to bundle and protect the wires after coming through the firewall.

Unfortunately, I just finished insulating the firewall, so putting in eyeball fittings might be a nightmare. I have the insulation and the engine mount in place. The though of all the shavings from drilling make me sick to think about cleaning up.

Thanks
 
... so putting in eyeball fittings might be a nightmare. I have the insulation and the engine mount in place. The though of all the shavings from drilling make me sick to think about cleaning up.

Thanks

I just purchased this hydraulic punch set from Amazon Aircraft Stuff. Tool quality is basic HF/Chinese but it makes an easy and clean punch thru the SS firewall.

https://www.amazon.com/OrangeA-Hydraulic-Knockout-Electrical-Punches/dp/B071DM1XHL/ref=sr_1_4?ie=UTF8&qid=1549456109&sr=8-4&keywords=hydraulic+punch
 
Any thoughts about using something like the aluminum bulkhead in the link below as a pass thru for the cable, if it were made out of stainless steel? It would not allow for rotation like an eyeball fitting, but it would require a much smaller hole in the firewall.

https://www.jegs.com/i/Earls/361/983210/10002/-1

Sounds reasonable. You could even shorten it lengthwise and drill out the bore a bit so you don't need a huge fitting. Chamfer the ends so you don't get a bad stress point on the cables, and you're good to go, IMO.
 
I figure this would be a smaller hole in the the FW and less mess. I plan to open up a hole in insulation and ss foil, then glue that edges of the opening to the FW. Let cure, then drill the hole through the FW. This will lead to no mess behind the insulation.
 
Back
Top