Firewall Insulation Glue

[jjconstant]

This is what I used:
http://www.aircraftspruce.com/catalo...axadhesive.php

It is supposed to be good to 2300F.

I am NOT an expert, my plane is NOT flying yet (hopefully in a month or so) but this was an area of concern after Dan Horton's extremely helpful thread. Dan has not mentioned this product but I think the spirit of his contribution has been to get folks to do research on what they believe will be safe and then work with the information to everyone's individual comfort level. Thank you Dan for all your work.

Prior to Dan's thread I had installed the 3/4 inch black foam stuff that was advertised as heat and sound insulation. I wanted both so I thought it was good. I saw Dan's thread and after changing my underwear struggled with a solution. Did a lot of research and finally decided that I would be comfortable with a sandwich of the stainless steel, the carborundum adhesive, fiberfrax, more adhesive, and the black foam. I sealed all edges with the adhesive. I took a sample coupon of the sandwich and exposed it to a butane flame. There was a bit of smoke, but no open flame. The smoke was from the binder in the fiberfrax. Much less than the same test without sealing the edges with the adhesive.

I am not recommending this, but it is what I have decided I'm comfortable with. I would have preferred something with no outgassing at all. In retrospect, I wish that I had known about these issues before I hung the engine, as I would have put all heat and sound insulation on the engine side, thereby avoiding the whole outgassing issue!

My concerns with my solution as it stands now, prior to actual in flight experience, is that when the carborundum glue is dry it has a bit of a crumbly brittleness to it. The sandwiched panels I put on the cabin side of the firewall are close fit between the aluminum angles, so friction is the predominant fastener. If the glue works even a little bit, it should be O.K.

Again, be aware that this is all coming from someone with zero flight experience in the airplane they're building, so I'm expecting to be surprised by many things...

respectfully,

Jeremy Constant

[DanH]

<<Dan has not mentioned this product.....>>

True enough. I actually have a bottle (about 10 years old) but it has never been opened. That particular design project went another direction before we got to a firewall check.

I think it is used to glue fiberfrax to plywood in the sandwich (stainless/fiberfrax/glue/plywood?) firewall on some composite designs. Perhaps we have a former glass builder who could chime it with details.

I've not checked red RTV as an adhesive, but I can tell you 3M FireBarrier 2000 (RTV silicone with an intumescent additive) will simply release and fall off a red hot firewall. At least it doesn't burst ito flame <g>

[gvgoff99]

This is from a multiple RV builder, Doug Knab,and is what we used on my firewall and the floor: "The material is made by E-A-R Specialty Composites. It is sold by: Buckley Industries PO box 574 Wichita, KS 67201 PH. 316-744-7587 The part no. is ADC-006. Most RV's need two sheets."

It was specifically made for airplanes and has the adhesive on it: http://www.earsc.com/pdfs/engineerin.../PB101ADCs.pdf

You put it on the firewall and the forward fuselage floor. Doug found it several years ago. It is not cheap. E-A-R is a pretty well known sound dampening company. (They also make the Confor foam for seats which is worth every penny!)

http://www.earsc.com/applications.as...39&parentid=37 for products E_A_R recommends for a pusher aircraft.

http://www.earsc.com/HOME/products/D...ex.asp?SID=360 for all their aircraft sound dampening/insulation materials.

http://www.earaircraft.com/ for some of the aircraft that they sound proof with the aviation stuff.

[DanH]

<<http://www.earaircraft.com/ for some of the aircraft that they sound proof with the aviation stuff.>>

Which ones install it on the cabin firewall?

Answer: none

I'm sure this stuff works great for reducing sound transmission....on a firewall, on a cabin sidewall, in the the roof, wherever. I'm also confident it will burn when the firewall is red hot.

§ 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.