Firewall Insulation Glue

In my uninsulated RV-8, my feet sometimes get uncomfortable hot. I am going to use Theomozite with foil on both sides for insulation material. I researched glues and found 3M 1300 with heat range of -30F to 300F to be my choice for attachment. Does anyone have experience with a better glue in this application?

1300 is your best bet.

Randy-

I'm not aware of any better option than 1300 (or 1300L which is sprayable). We use it extensively on all interior components on our company airplane. If you follow 3M's application instructions, you can't go wrong.

Spray 1300L

Jeff, 1300L is pretty thick as it comes from the can. Have you experience spraying it? What do you use for thinning? What is used for spray equipment?
The spray application would make a much nicer job than brushing.
Thanks.

Do you really want adhesive on the firewall?

After reading this thread in its entirety, I ordered some 1/2" thick refractory insulation from McMaster-Carr as described in post #64, along with some 5 mil aluminum foil. I plan to wrap the insulation in the foil, then drill some holes in the firewall stiffeners and use safety wire to retain the insulation panels, as described in post #73. As awful as a fire sounds, I figure that minimizing smoke and fumes in the cabin will improve my survival odds at least slightly.

Limited spraying experience.

Randy-

I haven't needed to spray 1300L for quite some time. Normally, I am applying only a small amount....maybe 6" x 6" for small interior panels or repairs. The few times I have sprayed, I used a cheepo touch-up spray gun (Ingersoll-Rand, I think) that I bought from Grainger or Northern Tool. If the 1300L is stirred properly, thinning shouldn't be necessary. Although, I'm sure a VERY small amount of MEK or Naptha would take care of the job. Since the areas between the firewall stiffeners are fairly small, you could probably get by with brushing the adhesive on without a problem. Spraying can be pretty messy no matter how careful you are.

I just used

RTV red spread in a "W" pattern on the back of the foil covered insulation. Been OK for 700hrs so far.

Adhesive

Contact cemet works great.

I used 3m 90 from an aerosol can. They call it "high strength" but I used it more because it has a higher temp rating than the other 3m contact cements. ~250 hours and no sign of separation.

A Thermozite insulation blanket was one of the first materials tested on the hot firewall rig. It is polyester fiber between aluminum foil sheets, and burns like a torch.

Below is a repeat from a previous thread. If ya'll keep slapping stupid things on the back sides of firewalls, soooner or later we're going to have a Darwin award winner right here in the RV community.

And BTW, 3M contact adhesive ignites in less than 20 seconds.
_______________________________

Sample was held in loose contact with the stainless "firewall" using two clamp strips at the vertical edges:



The sample was emitting heavy black smoke a few seconds after flipping the burner valve. It burst into flame in about 15 seconds. I dropped the Raytec and grabbed the camera. This was about 30 seconds into the test:



A few seconds later, from the "engine" side of the firewall:



The fibrous insulator between the aluminum foil sheets was rapidly consumed. The flames you see here were jetting out from between the foil sheets. The foil was mostly intact after the test, indicating a temperature at the insulation package less than 1100-1200 degrees F. The stainless temperature is around 1500-1700 F.

There is a very large difference between an appropriate firewall insulation and an FAR-compliant cabin wall insulation.

firewall

I also am one of those interested in insulating my firewall.
As Dan says, 3M spray adhesive is best left for glueing the headliner in your car!
It melts, the insulation falls off, then ignites in 20 or 30 seconds with any heat at all.
Water-based contact cement seems to perform much better, with the caveat of possible corrosion of bare aluminum.

fiberfrax adhesive

This is what I used:
http://www.aircraftspruce.com/catalog/cmpages/fiberfraxadhesive.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

<<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>

Firewall insulation

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/engineering/literature/ProductBulletins/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.asp?id=17&childid=39&parentid=37 for products E_A_R recommends for a pusher aircraft.

http://www.earsc.com/HOME/products/...ngComposites/ProductCatalog/index.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.

<<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.