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Re: firewall material
Hey guys;
We are not talking about wielding the metal here, but heat being applied more indirectly to the firewall, which will cause a gentler rise in temperature. I am not aware that zinc will undergo sublimation in this case, I think it will first melt and run off, but I don't know. That is what I will be testing. After the fire, will I have a bowl of zinc runoff, or nothing but zinc vapor? This should be a good determination. If I don’t' see zinc in the bowl, I won't be using this stuff anymore I my planes !!!!! (which so far has been on all my planes, as I recall).
Important stuff guys !!!!
p.s. There should be nothing under the cowling that can burn, if at all possible. Use metal and silicone lines, and when in doubt, try to burn the materials with a lighter, if it stops burning a couple of seconds after removing direct flames, it won’t sustain ignition by itself, and that’s a good thing.
Roger
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Re: firewall material
The zinc wont melt and run off, it will burn with a greenish tint to the flame then turn to a white ashy powder. I have cut and welded thousands of feet of this stuff for gratings, catwalks and various other structures.
If you have an inflight fire, the least of your worries is going to be a little bit of fumes off the firewall. What about the acrid eye burning wiring that is smoking up the cockpit, the fuel and oil and all the other goodies that are under the cowling. The fiberglass cowling really smells great when it starts to burn too.
If your that worried about a little bit a fumes on the firewall in the extremely rare chance that you have an inflight fire, then maybe you should take up something safer like being a couch potatoe and whatching TV while you knit a nice sweater... I am betting that the impact with mother earth is gonna mess you up a whole lot worse than sniffing a little zinc.
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Senior Member
Re: firewall material
Even though engine fires are pretty rare, the firewall is not an area to cut costs.
I usually refrain from “There I was…” stories. But for fire or smoke in an airplane I will make an exception. Maybe it will help someone make prudent decisions on circuit design and fireproofing.
I had in in-flight cockpit electrical fire in an MD-82. We went on the O2 masks and smoke goggles within seconds of detecting fumes. Even so, the burning insulation immediately started my eyes watering and nose running. From 35,000 feet we did a high dive into STL and were on the ground in 8 minutes.
Burnt insulation is rude stuff. My throat was raw, eyes burned and bloodshot, snot filled my mask. Both the FO and I reported that for a week after the event, everything we ate, sniffed, or drank, smelled and tasted like burning insulation. It’s like skunk. Not the worst smell in the world, but it stays with you.
Now, I doubt there are many Kitfoxes flying with pressure purging O2 masks and smoke goggles. So your exposure to fumes is going to be a bit rough if you have a fire.
With the above in mind, why add the possibility of zinc fumes to the mix? Stainless steel 0.025 sheet is available from ACS in cut sizes. A piece large enough for a Kitfox firewall and foot wells is about $93. To that you will need to add the 0.035 fuselage cover under the rudder pedals. That will set you back about $25. Then you can have fun cutting it to size and doing all the bends. Or….
Order a firewall from Kitfox. I did just that and received a nice kit with pre-cut and bent footwells, rivets, fasteners and bottom cover plate. Life is good.
Build safe, fly safe
John Pitkin
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Re: firewall material
Hey you guys are scaring me !
Shoot, maybe I should install one of those high dollar Halon system under the cowling or something !
My only really scary story was when my wood prop broke off my plane at 6000 AGL (I hear that is a rare event too, but still it did happen to me), but at least I had 6000 feet of cooling air on the engine, all the way down, down , down …
For me, I have to use the larger cowling to fit non-rotax engines, that means making my own firewall. I already have the galvanized stuff, so knowing what will happen to it in a fire is worth my time to test it (I kind of feel like a mythbuster too!).
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Re: firewall material
When you do your test, don't forget to add a container that will contain and focus the flame on the firewall (simulate a cowling) with a 60-120 mph wind entering from the other end.....
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Re: firewall material
Many good tips here and all are right on. I welded for a Power company, in a Nuclear Power plant. During the construction phase, I was given $.35 an hour over the rate to weld Galvanize. Yea, right. I so much as told them to put the $.35 where the sun don't shine.
As far as the material, I made a cardboard firewall, this gets transferred to
aluminum coil stock. This is the material used for window and door trim on siding jobs. It is about .018. When I'm satisfied, I will transfer or use this as a template to the S/S.(Aircraft Spruce). You can not use a portable aluminum brake for S/S. I have a tech advisor who has a 4ft. heavy brake I'm going to use for the final produce. -Tom, N.J.
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Re: firewall material
Oh how I long for those simpler days !!!!
Simple ice cream choice (chocolate or vanilla)
Simple summer drinks, Coke or Pepsi
Simple firewalls, Galvanized or Galvanized.
Roger
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Re: firewall material
Cessna and Piper used galvanized on the 150s. They are hard to keep clean and after some years, they rusted and looked terrible. The later 172s, 182s etc used stainless. Those are much nicer in appearance.
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Re: firewall material
Stainless is the only way to go.
In Canada for homebuilt category you only allowed to use SS
No galv or Alum allowed.
looks better as well
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Re: firewall material
I choose to use a FW-blanket (out of this forum, as well) http://www.heatblok.com/product.html
Hardly costs anything, great performance.
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