Firewall Passthrough

[JDA_BTR]

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.

[rocketman1988]

http://www.cleavelandtool.com/STAINL.../#.XC2IdS2ZPLY

[rv7charlie]

Or the same thing from Amazon or the local building supply for $10, plus some firesleeve & hose clamps.

[scsmith]

I really like these:

https://www.aircraftspruce.com/catal...clickkey=32868

[ronschreck]

Originally Posted by scsmith

I really like these:

https://www.aircraftspruce.com/catal...clickkey=32868

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.

[bobnoffs]

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!

[rocketman1988]

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

[ronschreck]

Originally Posted by rocketman1988

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! But I do appreciate your comment and concern.

[rocketman1988]

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...

[rv7charlie]

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?_fro...lange&_sacat=0
or
https://www.ebay.com/sch/i.html?_fro...ld+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.../firewall.html