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29-03 Firewall Sealant

G

Gandalf

Well Known Member
OK. So I finally was able to obtain some firewall sealant. I see one post saying that the sealant should be placed on the engine side of the firewall. However, there are a number of spots where the flange and skin meet that really can only be sealed from the cockpit side. How did folks seal the firewall: engine side only, cockpit side only or both as needed?

Thanks,
Jeff
 
Gandalf said:
OK. So I finally was able to obtain some firewall sealant. I see one post saying that the sealant should be placed on the engine side of the firewall. However, there are a number of spots where the flange and skin meet that really can only be sealed from the cockpit side. How did folks seal the firewall: engine side only, cockpit side only or both as needed?

Thanks,
Jeff
Click to expand...

Both.... Probably overkill, but I don't want FWF smoke/fumes in the cockpit!
 
Phantom30 said:
Both.... Probably overkill, but I don't want FWF smoke/fumes in the cockpit!
Click to expand...

Ric... I needed to do both sides to pass the flashlight test. Curious that my original plans called for fuel tank sealant and the revision now calls for firewall sealant.

I am a little confused if I should use fuel tank sealant or firewall sealant for the firewall rivet heads? Also the firewall sealant did not come with a screw on nozzle. Is that normal?

Jeff
 
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I talked to the factory last week and asked what they recommended for firewall sealant. They responded with 'fuel tank sealant'.; Pro-seal.

I asked about what I had seen in the Homebuilder help video, which was putting on a bead of Hi-Temp RTV 'make your own gasket' stuff and was told that you can use it, but it typically doesn't adhere to Stainless well and will sometimes peel off. That's why they recommend the pro-seal/fuel tank sealant.

Bob
 
bhassel said:
I talked to the factory last week and asked what they recommended for firewall sealant. They responded with 'fuel tank sealant'.; Pro-seal.

I asked about what I had seen in the Homebuilder help video, which was putting on a bead of Hi-Temp RTV 'make your own gasket' stuff and was told that you can use it, but it typically doesn't adhere to Stainless well and will sometimes peel off. That's why they recommend the pro-seal/fuel tank sealant.

Bob
Click to expand...

Bob... That is interesting and useful information. Combined with info from RVator below, I wonder if firewall sealant may still be the best choice for sealing large openings such as perimeter gaps in the firewall, while using fuel tank sealant for mating surfaces that are to be riveted.

FIREWALL SEALANT
When the prototype RV-12 was built, engi- neering specified MC-CS-1900 high temperature firewall sealant. This was a stock item, straight out of our Accessories Catalog. It came in handy tubes that made mixing and applying it easy and simple. Buy tube, smear on airplane, rivet fire- wall, life is good.
Except. Except when our shipping supervisor found that shipping rules and regulations had changed which suddenly made firewall sealant a ?hazardous material? which could only be shipped by very expensive means by people with expen- sive qualifications. The penalties for ignoring said regulations were severe ? go-to-jail kind of se- vere. We stopped shipping and began research- ing alternatives. Within a couple of weeks, engi- neering determined that regular MC-236-B2 fuel tank sealant was adequate for sealing the firewall bulk- heads. This is a chemically different material that can be shipped without trouble. Sealing cable and wiring penetrations through the firewall will still require the high temp material and we?re working on ways to solve the shipping problem.
 
Just finished the lower firewall with the stiffener and the stiffener calls out tank sealant for the rivet. I couldn't find where it calls out sealing the rest of the rivets until I found this thread and now see that it's section 29. Since I had to use sealant to join the lower FW and the shelf I decided I should cover all the rivets I could while I had this junk out. I used the paper punch re-enforcment doughnuts for each rivet and it came out clean and was simple - just wanted to pass that on.
 
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