I also say WOW! What if someone uses it that way on a fuel fitting downstream of the last filter. The residual could easily clog up the very small jets and orifices in the carburetors. Its been awhile since I read thru the FAA publication on recommended practices for aircraft construction and maintenance, but I believe pushing sealant into the fuel system is totally against their directions.
The stuff Kitfox recommends is Permatex Permashield 85420 Gasket Dressing and Sealant. When you read the application directions it says nothing about threads, but talks only about gasket and flange surfaces. It is specified as being fuel, ethanol resistant.
Personally, I will continue to use it by applying to the male thread only and leaving the last couple of threads bare.
Jim Ott
Portland, OR
Kitfox SS7 flying
Rotax 912ULS
If I may add my 2 cents worth. I didn't deliberately place this sealant to the tank threads first but I did apply it to the fitting threads and installed it. I found that I was not holding air in the tank via the balloon on the cap vent tube. I removed and reinstalled the fitting about three times, each time I reapplied the sealant to the male threads. By then I had residual sealant on the tank threads and it did end up sealing up. I fully expected to find debris within the fuel system and as I have stated before the only stuff I found (still finding it a bit) was the little white granuals that resemble sand. Because of this finding during fuel samples, I have removed the large fuel filter and cut it open. I found absolutely nothing in that filter. I think at the 100 hr I will change the inline filter I have coming off the header tank. I suspect that that is where all the debris might be. Either that or the sump drains are doing a fine job at capturing it and Im purging it on fuel sampling.
Eddie Forward
Flying
SS7, 912iS, Garmin G3X
Interesting. My instructions specifically specified Permatex 80938 (9AR) for this. I recently had to remove one of my tank quick drains and asked John at Kitfox what they now used. He said it was the 9AR. It is creamy white in color as opposed to the blue 85420 you guys are talking about. I think that the 9AR has possibly been discontinued by Permatex, but I was able to get a new tube on Amazon, at a ridiculously high price. Threading and sealing a metal fitting directly into a tapped fiberglass hole is potentially problematic, and there should be a better way. If I was starting over, I believe I'd drill and tap the tanks oversize, then bond brass threaded reducer bushings into the tanks with a structural epoxy. A metal to metal joint on fittings that may have to be removed would be a much better design, IMHO. Better still would be to redesign the tanks slightly to allow that to be done while also providing additional clearance to better accommodate the metallic bushings.
John Evens
Arvada, CO
Kitfox SS7 N27JE
EAA Lifetime
Chap. 43 honorary Lifetime
Guys I really appreciate all of the input, not that I feel any better about the situation as a whole... I think I will simply have to diligently check the filters through the first hours. Maybe to some extra time running on the ground before any flight takes place. My wonder remains, will everything that might release, release in the first few hours... or might I have a nasty surprise many hours down the line. I may scope the inside of the tanks/header tank with a camera just to see how much is in there...
I built my whole kit using 9AR on every tapered threaded fitting including fuel, brakes, oil and coolant and have had zero leaks for 740 hours; I like the stuff. However I recently used it up and bought the blue 85420 which I have not used yet. My understanding was the 9AR is no longer available and Kitfox factory has been selling the 85420. I always used the 9AR by putting it only on the male thread, but don't remember what the actual instructions on the tube said. I believe the 9AR was also described as a gasket/flange sealant rather than a thread sealant.
I understand from this forum that many folks have been using Loctite thread sealants on their projects with apparently good results (those thread sealants instruct you to apply only to the male thread). My own hesitation in using them is that they cure to a hard non-flexible condition which is fine for metal to metal fittings torqued to proper tightness. But for a metal fitting into fiberglass where the torque value is extremely low I want the non-hardening sealant that remains flexible and of course is compatible with ethanol containing fuel. My 2 cents.
Jim Ott
Portland, OR
Kitfox SS7 flying
Rotax 912ULS
Hello everyone,
Have you thought of researching Hylomar Universal Blue? It does not harden and it works well with various fuels. Might be worthwhile to look into it.
Happy flying!
Flying Felix
Per John's comments - exactly what I found to be true.
Permatex 9AR was re-branded Permatex Tack & Seal Gasket Sealant Item # 80938; and, the tube clearly has 9AR in parentheses following the Item number 80938.
It's the same stuff; or, similar enough to be indistinguishable in physical characteristics or uses.
Business just loves to rebrand stuff.
Dave S
Kitfox 7 Trigear (Flying since 2009)
912ULS Warp Drive
St Paul, MN
This is the blue goo in question:
https://www.amazon.com/Permatex-Perm...a-585235998177
It does state that it is resistant to ethanol.
Would someone describe what the banjo fittings are or show a picture of these. I'm not familiar with this term.