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Cork firewall insulation
- Thread starter digidocs
- Start date
Larry DeCamp
Well Known Member
Why firewall side
Educate me David. The properties are encouraging, good discovery! I thought the SS firewall was the flame barrier. Therefore insulation could go on the cockpit side with less concern for oil contamination and physical abuse ?
Educate me David. The properties are encouraging, good discovery! I thought the SS firewall was the flame barrier. Therefore insulation could go on the cockpit side with less concern for oil contamination and physical abuse ?
rleffler
Well Known Member
Please search for Dan Horton's (DANH) thread. Many of the insulators will ignite or generate caustic fumes once the firewall reaches certain temps. Dan has done a pretty comprehensive test of the popular products.
I'm having a little fun with you Steve, just to make a point. At least you're using materials that won't get you killed.
I cannot grasp what folks are thinking sometimes. Tonight I walked into a hangar to say hello, and found that the young man had covered the cabin side of his firewall with aluminized mylar plastic bubble wrap.
BillL
Well Known Member
Did you use the method of covering both sides of the insulation with stainless steel tool wrap? (used for heat treating) That is why Dan was recommending covering the ceramic matt and that makes some sense. It would be good to know if you did this and it still leaked.
David, assume a simple fiberfrax felt/stainless foil overlay on the engine side of a firewall.
First, the perimeter of the firewall gets a filet of 3M FireBarrier 2000 to close the small openings created by the fluting slots (gas seal...important!).
Fiberfrax felt and stainless foil are fastened with stainless pop rivets.
The entire perimeter and the openings around all subsequent fitting penetrations are sealed with FireBarrier.
So how does the water get in?
I'd argue it does not...and I've been flying such an installation about 400 hours now...in a climate not much different from Houston, or parked outside away from home, etc. It's been durable too.
Did your water test involve batting or felt? Was it notably hygroscopic (absorbs moisture directly from the air), or were you introducing liquid water?
That said, I have no particular objection to replacing the fiberfrax felt with cork sheet, assuming it performs as well when subjected to 25 sq inches at 2000F. Even if it does not perform as well from a thermal standpoint, a cork sandwich installation on the engine side is unlikely to cause harm.
First, the perimeter of the firewall gets a filet of 3M FireBarrier 2000 to close the small openings created by the fluting slots (gas seal...important!).
Fiberfrax felt and stainless foil are fastened with stainless pop rivets.
The entire perimeter and the openings around all subsequent fitting penetrations are sealed with FireBarrier.
So how does the water get in?
I'd argue it does not...and I've been flying such an installation about 400 hours now...in a climate not much different from Houston, or parked outside away from home, etc. It's been durable too.
Did your water test involve batting or felt? Was it notably hygroscopic (absorbs moisture directly from the air), or were you introducing liquid water?
That said, I have no particular objection to replacing the fiberfrax felt with cork sheet, assuming it performs as well when subjected to 25 sq inches at 2000F. Even if it does not perform as well from a thermal standpoint, a cork sandwich installation on the engine side is unlikely to cause harm.
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While we're here, a quick reminder. This is Thermozite Plus, an aluminum foil backed polyester fiber insulation (see: http://www.ozite.com/products/commercial/thermozite/). It was sold by a popular vendor as "firewall insulation", and can still be seen inside a lot of RVs. This is 15 seconds after the burner was turned on, on the opposite side of a stainless steel firewall sheet. It ignites as soon as the metal gets hot, and it won't go out until the metal cools or it is all consumed. If you have an engine fire with something like this stuff installed, you may die badly. For sure it is much worse than no insulation at all.
For contrast, this is 5 minutes into a burn run, with SS foil/ceramic fiber on the hot side. Big difference. Note that insulating the engine side protects the structure, which is held together with aluminum rivets (liquid at 1100F).
§ 23.1191 Firewalls.
(f) Compliance with the criteria for fireproof materials or components must be shown as follows:
(1) The flame to which the materials or components are subjected must be 2,000 ±150 °F.
(2) Sheet materials approximately 10 inches square must be subjected to the flame from a suitable burner.
(3) The flame must be large enough to maintain the required test temperature over an area approximately five inches square.
(g) Firewall materials and fittings must resist flame penetration for at least 15 minutes.
§ 23.1182 Nacelle areas behind firewalls.
Components, lines, and fittings, except those subject to the provisions of §23.1351(e), located behind the engine-compartment firewall must be constructed of such materials and located at such distances from the firewall that they will not suffer damage sufficient to endanger the airplane if a portion of the engine side of the firewall is subjected to a flame temperature of not less than 2000 °F for 15 minutes.
For contrast, this is 5 minutes into a burn run, with SS foil/ceramic fiber on the hot side. Big difference. Note that insulating the engine side protects the structure, which is held together with aluminum rivets (liquid at 1100F).
§ 23.1191 Firewalls.
(f) Compliance with the criteria for fireproof materials or components must be shown as follows:
(1) The flame to which the materials or components are subjected must be 2,000 ±150 °F.
(2) Sheet materials approximately 10 inches square must be subjected to the flame from a suitable burner.
(3) The flame must be large enough to maintain the required test temperature over an area approximately five inches square.
(g) Firewall materials and fittings must resist flame penetration for at least 15 minutes.
§ 23.1182 Nacelle areas behind firewalls.
Components, lines, and fittings, except those subject to the provisions of §23.1351(e), located behind the engine-compartment firewall must be constructed of such materials and located at such distances from the firewall that they will not suffer damage sufficient to endanger the airplane if a portion of the engine side of the firewall is subjected to a flame temperature of not less than 2000 °F for 15 minutes.
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flyboy1963
Well Known Member
new alarm system?
..but Dan, wouldn't the popping sound be a really good indicator that you have an engine fire?
seriously, we all appreciate your dedication to saving us from some bad ideas, hangar lies that get re-told as fact, and misleading advertising.
I'd love to see a recap of what you did on your -8....I tried to emulate by insulating the firewall and floor to withstand the most heat, then the sides and aft cabin floor, then upper fuselage, altho once the fiberglass goes, and there's boiling oil on the windshield, I think we're out of options!
..but Dan, wouldn't the popping sound be a really good indicator that you have an engine fire?
seriously, we all appreciate your dedication to saving us from some bad ideas, hangar lies that get re-told as fact, and misleading advertising.
I'd love to see a recap of what you did on your -8....I tried to emulate by insulating the firewall and floor to withstand the most heat, then the sides and aft cabin floor, then upper fuselage, altho once the fiberglass goes, and there's boiling oil on the windshield, I think we're out of options!
