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Attaching soundproofing/fire protection to firewall

LettersFromFlyoverCountry

Well Known Member
I can certainly see why glue should not be used to attach soundproofing/fire barrier on the cabin side of the firewall, but I'm curious as to WHAT fasteners people are using to attach material here?

Like a lot of dunderheads, I've waited until all the holes, lines, and pass-throughs have been completed before tackling this task. I've made a series of templates and I've probably got about 6 or 7 pieces I'll need to cut in a material I've not yet chosen (that particular topic is getting to be like primer wars, so let's just leave that one alone).

Assuming fasteners should be used, what fasteners? And how many? Etc.
Please post pictures.
 
I followed a suggestion Dan Horton made on one of those threads to which you alluded: I wrapped ceramic refractory wool batting with heavy aluminum foil, made to fit cardboard patterns I had previously created. Made slits to get past previously installed cables. Then drilled holes in various locations on the firewall stiffeners, and used .025 safety wire to lash the insulation panels in place. It was fairly straightforward to install due to not having the forward skin on yet. Would not be fun to r&r once it's in place, though.

Not flying, so I can't report observations. And even if I was, I'd have no basis for comparison (don't have enough experience in other RVs) so I wouldn't be able to offer an opinion on utility anyway.

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Supplier

Lars,

Where did you buy the batting from? A quick internet search only yeilded a few sources that had 500 pc minimum orders. :(
 
Lars,

Where did you buy the batting from? A quick internet search only yeilded a few sources that had 500 pc minimum orders. :(

...what Mike wrote. There's a thread on here somewhere about firewall insulation. Dan Horton did a bunch of flame tests. That product survived and had minimal outgassing.

Disclaimer: As Bob mentioned, I'll leave it to others to debate the efficacy, necessity and utility :)

If you choose to use this stuff, you will wind up with a LOT of extra. I could probably insulate 6 or 7 more side by side RV firewalls with what I have left over, despite a few screwups.
 
Bob, after you've decided on a product...
If you want some 1/4" ceramic sheeting (same as Mike linked, but thinner: McMaster 93315K51), I have a 20' roll that I'll never be able to use all of. You're more than welcome to some of it...
 
..That product survived and had minimal outgassing.

Completely unaffected and had no outgassing, or at least none I could detect. The only apparent risk to using this material inside the cabin is inhalation of airborne fiber, which is why it should be fully encapsulated in foil.

As I recall, credit for locating the material and source is due Don Pansier: page 3492 of the McMaster-Carr catalog. Part#93315K82 is 1/2 thick. Might want to look at part #'s 93315K34 and 93315K54.

Bob's question.....I don't know, as my own airplane is not insulated on the cabin side. It is far more effective to insulate the engine side of the firewall, with this product or a dozen others.
 
Insulate for Comfort, Safety, or both??

It is far more effective to insulate the engine side of the firewall, with this product or a dozen others.

As I understand Dan's statement here, this is in relation to keeping the cabin livable in case of an engine fire.

I am going to use the cabin side insulation for normal day-to-day comfort reasons, (there is a lot of radiant heat from the firewall) and will also end up with firewall forward insulation like Dan recommends, for fire safety.
 
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It is far more effective to insulate the engine side of the firewall, with this product or a dozen others.

I could not agree more, at least in principle.

Confession: By the time it occurred to me to do something about firewall insulation (by reading threads on this board) I had a substantial amount of stuff fastened to the firewall, including the engine on its mount. Since mine is a 7, it was also on the gear, and my carefully constructed rolling fuselage cart had moved on to another builder. I couldn't face the prospect of de-mounting everything FWF to insulate, so I opted for the above-described solution. That, and a very careful scrutiny of fuel sources (gasoline and oil systems).

I decided I would rather have an inferior (but generally safe) insulation system than none at all. At the very least I hope it will provide some relief from radiant heating due to normal operation. Time will tell.

Ahh--another man with left-hand scissors--we are an elite few, you know :D

Now that's funny. Good eyes! Turns out that except for writing, I'm ambidextrous. As my wife points out, I can make mistakes with both hands :cool:
 
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I suppose I shouldn't be surprised that in a thread about ways to fasten firewall material to the firewall, yet another thread broke out about what material to use. Focus, people! ;)

Dan, how did you fasten it on the engine side of the firewall?
 
..I am going to use the cabin side insulation for normal day-to-day comfort reasons, (there is a lot of radiant heat from the firewall) and will also end up with firewall forward insulation like Dan recommends, for fire safety.

Normal and emergency temperatures are the same insulation task. Engine- side insulation is more efficient for both cases, ie less weight or bulk for a given insulation value. The reason is simple; engine side insulation slows heat transfer to the firewall support structure. A lot of that structure (notably many feet of extruded aluminum angle) is exposed to the cabin volume with most backside insulation applications.

That said, yes, there are practical limits to how much thickness you can stack on the forward side of the firewall. From there an additional layer on the cabin side would be the only way to add more comfort R-value.

Is it necessary? You've made me curious. I'll take the Raytec along on the next flight for a measurement of firewall temperature.

Dan, how did you fasten it on the engine side of the firewall?

Stainless blind rivets with little stainless washers. With care the majority go through support angles between driven rivets.
 
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Bob, after you've decided on a product...
If you want some 1/4" ceramic sheeting (same as Mike linked, but thinner: McMaster 93315K51), I have a 20' roll that I'll never be able to use all of. You're more than welcome to some of it...

that'd be great. I hope to get going on it in about 3 weeks. I could easily drive down and pick it up sometime.
 
I suppose I shouldn't be surprised that in a thread about ways to fasten firewall material to the firewall, yet another thread broke out about what material to use. Focus, people! ;)

Dan, how did you fasten it on the engine side of the firewall?

True 'dat. However, the choice of material had some relevance, at least in my case. Mostly because by the time I'd wrapped the ceramic wool in aluminum, it turned into a fairly stiff board that was easily supported with a few strands of safety wire strung between the stiffener angles. A more limp material might have been more problematic to fix in place with that method.
 
Just a suggestion...

Fold neat flanges into the edge of each foil envelope. Clip the flanges to the aluminum firewall support angles with ordinary steel binder clips from Office Depot. Remove the little wire handles.

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Binder clips seem like a great idea, Dan. We also have these things in our office supply room... looks like they could also work for this application:

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More info here.

Now I'm thinking about using some of these clips to secure envelopes of ceramic batting and 0.002" stainless foil.

mcb
 
Ahhh, the ever popular binder clips. We use them to close potato chip bags, hold garbage bags in place on the trash can, and also use them to make airplane parts. They are a great invention.

For those who are contemplating using some sort of batt insulation, may I ask a question: What is your plan for this material when, not if, it gets soaking wet?

Yes, most of those materials will drain most of the water (or gas, or oil) but will it actually dry out or will it mold and corrode?

And for goodness sake, don't even think about using the stuff from the auto parts store that is made from recycled clothing. That stuff seems to have a knack for holding 1000x its weight in water. Ugh.
 
Yes, most of those materials will drain most of the water (or gas, or oil) but will it actually dry out or will it mold and corrode?

Worth considering.

Cereblanket, from the McMaster-Carr catalog:

If exposed to oil or water, this alumina silica ceramic fiber insulation isn't permanently affected—its thermal and physical properties restore after drying.

Thermal Ceramics data sheet here:
http://www.barteltinsulation.com/pdfs/CERAMICBLANKET.pdf

The MIL-I-24244 approval means no corrosion of a heated, stressed stainless steel coupon after 28 days of contact with whatever leaches from the insulation when wet.

Soundcoat CSU data sheet here:

http://www.soundcoat.com/soundcoatgasketing.pdf

PVC/NBR/CR foam with 10% water absorption by weight. They plainly list it as a "sponge type" ;)

PVC/NBR/CR? Oh yeah, somebody send some for a firewall test. You can buy it right here:

http://www.flyboyaccessories.com/st...ducts_id=304&zenid=mbeiv5874ooo981rk4599g6hr0
 
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Fire Barrier 2000

What is your plan for this material when, not if, it gets soaking wet?

After I got the SS foil laid up over the ceramic batting and installed it on the firewall (forward side) I went around it with Fire Barrier 2000 to prevent moisture penetration. In flight the engine side of the firewall would evaporate any moisture that found its way there. Parked the airplane will remain in a hangar when home, and when away from home it will have a cover that covers the rear cowl gap.

After all that, in the unlikely event moisture still creates a problem I will remove the batting.
 
Worth considering.

Cereblanket, from the McMaster-Carr catalog:

If exposed to oil or water, this alumina silica ceramic fiber insulation isn't permanently affected?its thermal and physical properties restore after drying.

Thermal Ceramics data sheet here:
http://www.barteltinsulation.com/pdfs/CERAMICBLANKET.pdf

The MIL-I-24244 approval means no corrosion of a heated, stressed stainless steel coupon after 28 days of contact with whatever leaches from the insulation when wet.

Soundcoat CSU data sheet here:

http://www.soundcoat.com/soundcoatgasketing.pdf

PVC/NBR/CR foam with 10% water absorption by weight. They plainly list it as a "sponge type" ;)

PVC/NBR/CR? Oh yeah, somebody send some for a firewall test. You can buy it right here:

http://www.flyboyaccessories.com/st...ducts_id=304&zenid=mbeiv5874ooo981rk4599g6hr0

Having now had personal experience with the thermal ceramic batting, and with accidentally spilling liquid on it (coffee, not beer) I can tell you what I saw: the coffee, which was hot, mostly beaded up and ran off. Very little actually soaked in. That was a sheet lying horizontally on my workbench.

An additional note: for those planning on using this material, wear gloves when you handle it. It's much worse than fiberglass insulation in generation of itchy particles.
 
In response to other comments, we recommend the Soundcoat M for sidewalls, not firewalls. Since the face is waterproof, when edge sealed with RTV, as recommended, it is virtually waterproof even though it is an open cell foam.

Soundcoat CSU is closed cell foam, and waterproof.

We like these products to prevent hot feet. That is our main concern.

Regarding batt insulation, I've seen many instances of corrosion caused by this type of stuff getting wet. That is the only reason I pointed it out.

Dan H is correct that anything added to the firewall may increase your risks and should be considered. My personal opinion is that hot feet are unacceptable and the small risk of adding insulation is worthwhile. YMMV.

Bottom line: We're not in this for the money. I still have my day job, and my main assistant is my son, a senior in college. We sell the stuff that we've found useful, stuff that other RVers might like, and nothing we sell makes enough money to get into an online feud. Ugh. My apologies if any of my previous comments were hurtful to anyone.
 
In answer to your original question......

You might try looking at Click Bond products. I used them in my -7A to hold cable ties but also to attach nut plates to my wingtip installation. It is a system that uses a two-part adhesive and is much easier than nut plates. I recently took off my wingtip to install an Archer VOR antenna and the Click Bond nutplates showed no sign of loosening. I used them in the center tunnel to attach cable ties and they are holding well also.

If you are interested, look on their website and search insulation attachments. One reason I decided not to install firewall insulation was the difficulty in getting it to stay with the usual adhesives. Dan Checkoway chronicled how he installed his and then a while later chronicled how the adhesive didn't hold. I don't have any personal experience with the Click Bond firewall insulation anchors but I'm a big fan of their products and plan to use them in the near future with passing new wires and coax for my new panel.
 
I followed a suggestion Dan Horton made on one of those threads to which you alluded: I wrapped ceramic refractory wool batting with heavy aluminum foil, made to fit cardboard patterns I had previously created. Made slits to get past previously installed cables. Then drilled holes in various locations on the firewall stiffeners, and used .025 safety wire to lash the insulation panels in place. It was fairly straightforward to install due to not having the forward skin on yet. Would not be fun to r&r once it's in place, though.
Lars,
What did you use for the aluminum foil? Thickness? width? Source?

Thanks,
GH
 
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