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Firewall prime

wirejock

Well Known Member
I searched and found one thread on priming or not priming the stainless firewall. Not much help.
Given it's function and the possibility of intense heat from a fire, priming seems like a bad idea.
What about the aluminum braces, gussets, etc riveted to the inboard side? If it's hot enough to cook primer on the cockpit side of the firewall, the primer on the braces would be just as susceptible to smoking. I'm thinking none of it should be primed but they are dissimilar metals. What to do?
What about the sealant for the holes. What product is used that won't cook and poison the pilot before he can land. Maybe I'm over thinking it.
Comments appreciated.
 
firewall prime

Pretty hard to get paint to stick to the stainless steel firewall so I didn't prime it either side. The stainless steel is not likely to corrode. All the rest of my interior parts are primed and the cockpit is topcoated with Sherwin Williams Jetflex WR, so the aluminum angle braces riveted to the firewall are painted with this also. I didn't use sealant on any of the rivets between the firewall and aluminum angle braces. The rivets should be a gas tight fit, so I'm not worried about dissimilar metal corrosion. I will be using sealant, probably 3M Fire Barrier Sealant between the F-601K firewall recess and firewall and also between the heater valve (stainless steel, not the aluminum one) and the firewall.
 
I am sure you will get a lot of opinions.
I am not so worried about primer on the firewall as some are. But, in the very unscientific burn tests I did, it does put off smoke, and will burn. But there is so little it did not make too much difference.

I am much more worried about the insulation of choice. The black spongy foam generates lots of white smoke. I strongly suggest you make a very simple mock firewall and do your own burn tests. I did, and it significantly changed my mind on what to use on or within 10 inches in of the firewall.

Dan H has done a lot of burn tests (posted in the forums) which are good to use when narrowing down your choices.

For what it is worth, I chose no primer or paint on the firewall. I used ultra high temp ceramic insulation from McMastercarr wrapped in heavy duty aluminum foil. Attached mechanically to the inside of the firewall. Filled small holes with 3M Fire Barrier 2000
http://www.mcmaster.com/#thermal-insulation/=vomsu5
http://www.aircraftspruce.com/catalog/appages/firewall2000caulk.php?clickkey=42669
 
Super K - aka Super Koropon - has a published continuous duty service limit of 350F. I've had SuperK on a 316SS heat muff for 3,000+ hours with a temp label that has the 450F spot activated. The Super K looks pretty much like it did in 1983 when I painted it. That said, I don't think I'd put it on my SS firewall.

dk
 
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No primer

I read through the same posts, ect. I decided to leave all firewall components unprimed metal to minimize any outgassing should it get hot. I'd expect it to get pretty warm in normal operation in any case. Of course, when it comes to paint the cockpit, it will stay paint-free.
 
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