FWIW, I found the proseal in my Grumman AA5 tanks (which are similar to the RV design) had softened after 38 years of being soaked in avgas. The areas at the bottom along the inboard rib had softened to the consistency of modeling clay, and could be scraped off with a fingernail. This was only evident for about an inch from the bottom - above that it looked good. That is probably the only area that was always soaking in avgas, since it's probably near the limit level of useable fuel. Maybe only an occasional drying out is needed to prevent the problem?
FWIW, I found the proseal in my Grumman AA5 tanks (which are similar to the RV design) had softened after 38 years of being soaked in avgas. The areas at the bottom along the inboard rib had softened to the consistency of modeling clay, and could be scraped off with a fingernail. This was only evident for about an inch from the bottom - above that it looked good. That is probably the only area that was always soaking in avgas, since it's probably near the limit level of useable fuel. Maybe only an occasional drying out is needed to prevent the problem?
Scraping and resealing fixed the leak.
Stan
FWIW............... is nothing.
Your tanks were NOT sealed 38 years ago with MC 236-B2. It was developed long AFTER your AA5 was built. MC 236-B2 was in fact developed by a chemist at Morton Thiokol.
Had some extra time this afternoon, did some searching....
The blue dye is 1,4 ? dialkylamino antraquinone. There are other interesting thngs in there too. Ok, chem majors, let's hear it.....
A forum speaker at OSH a couple years ago said 100LL was formulated with 82 ingredients. His point being, alternate fuel from plant life would have 6-8 elements.
OK - so what IS causing the sealant to go soft outside the tank?
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I wonder if this is just a Flamemaster sealer issue or does it happen with Proseal 890 also,,,what type sealer did you guys have the problem with? I used Flamemaster from Vans and had the same issue with the area of the leaks becoming soft. I have used proseal 890 (I believe it is a PPG product) on other aircraft for years and have never seen this problem. I believe both these sealers are Mil Spec 8802 sealers but there may be a difference in them.
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Jim Poe
RV9 First Flight 2/23/09
s/n 91416