Date: 13 Jul 1995 09:13:35 U From: "Judd Stewart" Subject: Epoxy Fuel Compatibility People, RAF and NAT have been recommending the new 2427 system, the physical properties are better and some prefer the way it wets out. My concern is FUEL (auto/avgas) susceptibility (Phil Johnson- read this as a actual concern, unlike my posting about which side of the line I should cut the templates to!). 1>I spoke with the Hexcel factory (PHIL CUSPERT) and was informed they did not do any testing. Phil suggested that I make coupons and precisely weigh each and then expose and re-weigh. Has anyone done any testing? FYI- Hexcel is planning on discontinuing 2183/2184 hardeners in the future. The date has not been set. Hopefully they will inform us so that we/us/me can purchase enough to finish. Judd Date: Thu, 13 Jul 1995 15:41:10 -0400 (EDT) From: Tech Support - Rick Subject: Re: Epoxy Fuel Compatibility Nat already did the testing as far as AvGas. There were no problems. I checked before I started using 2427. Rick Date: Fri, 14 Jul 1995 08:31:26 -0400 From: Phillip.Johnson@Lockheed.on.ca (Phillip Johnson) Subject: Fuel & Epoxy Jud Stewart Writes: > My concern is FUEL (auto/avgas) susceptibility (Phil Johnson- read > this as a actual concern, unlike my posting about which side of the > line I should cut the templates to!). Thank you Jud for the info. I guess I will make up a few squares with the new hardener and test it in Auto Gas. I'm still on the Safe-T-Poxy 2. I gave in on the last purchase, better the devil you know and all that. It sounds like I will not be able to complete using this hardener though. By the way it's not only the auto faction that should be concerned, it looks as if there will me a move to unleaded fuel in the near future and once that gets underway I wouldn't mind betting that regular AVGAS may be difficult to obtain. In five to ten years you want to be sure that your fuel tanks are still going to be OK. P.S. Sorry if my post about "which side of the line to cut" was a bit gruff. Maybe I need to tone down my written word or maybe you should all read it as "it's another posting from Phil and accept the way I write as gruff" its unintended. Phillip Johnson Date: Fri, 14 Jul 1995 12:49:08 -0400 (EDT) From: Tech Support - Rick Subject: Re: Fuel & Epoxy > By the way it's not only the auto faction that should be concerned, it > looks as if there will me a move to unleaded fuel in the near future > and once that gets underway I wouldn't mind betting that regular AVGAS > may be difficult to obtain. In five to ten years you want to be sure > that your fuel tanks are still going to be OK. The concern with auto gas is not the gas but the alcohol and some of the solvent additives. The alcohol attacks the epoxy. Since aircraft are not allowed to have the alcohol in our fuel , this should not be a concern. The FAA frowns very heavily on the notion of alcohol in gas due to the fact it allows water in the tank. The feds have known about this since the '60's. Rick C. "if a shoebox had wings, we could make it fly!"--the Rocketeer "if it's got wings, I can fly it!"----Anonymous Pilot "And let me know when Elvis shows up!"---Beldar Conehead Date: Fri, 14 Jul 1995 14:24:48 -0400 From: Phillip.Johnson@Lockheed.on.ca (Phillip Johnson) Rick Writes > The concern with auto gas is not the gas but the alcohol and some > of the solvent additives. The alcohol attacks the epoxy. Since > aircraft are not allowed to have the alcohol in our fuel , this > should not be a concern. The FAA frowns very heavily on the notion > of alcohol in gas due to the fact it allows water in the tank. The > feds have known about this since the '60's. It's these other additives that are of concern since, as you say, "The FAA frowns very heavily on the notion of alcohol in gas due to the fact it allows water in the tank". I assume that auto gas users will check for alcohol. These other additives may also be in the new UL AVGAS/AUTO FUEL and since the fuel may not be designed with epoxy impregnated tanks in mind, it should be tested for these properties as well. Phillip Johnson. From: Lee Devlin Subject: Re: Fuel & Epoxy Date: Fri, 14 Jul 95 12:30:07 MDT Rick wrote: > The concern with auto gas is not the gas but the alcohol and some of the > solvent additives. The alcohol attacks the epoxy. Since aircraft are not > allowed to have the alcohol in our fuel , this should not be a concern. > The FAA frowns very heavily on the notion of alcohol in gas due to the > fact it allows water in the tank. The feds have known about this since > the '60's. Alcohol and water are miscible but it does not necessarily 'attract' the water, i.e. it is not hygroscopic. Many 'dry gas' products actually use alcohols to absorb the water and mix it with the rest of the fuel so that it doesn't end up getting delivered to the engine in one big slug or freeze in a fuel line. The only real safety issue with alcohol is its ability to disolve parts of the fuel system like rubber hoses and seals (and perhaps cured epoxy resin?). This is particularly true with methanol and somewhat less of a problem with ethanol, which is a commonly used alcohol additive. I fly out of Greeley, CO and they carry Phillips 'unleaded' fuel in one of their pumps but I don't think it is an automotive blend judging by its pleasant smell. (It's more reminiscent of 80 octane with the pink color and all.) Remember when automotive gasoline used to smell good? The autogas you get today smells terrible and it really stays with you if you get any on you. Autogas isn't really an option for most Cozy drivers today since the high compression ratio of an O-360 requires octane that you can only get with 100LL. I suspect that in 5 years that there will be a unleaded replacement for 100LL. It will no doubt contain one of the octane enhancing ethers like MTBE and will probably smell terrible :-(. Incidentally, the test for the suitability of the ethers in aviation fuels system is still being conducted by literally thousands of unsuspecting participants. Lee Devlin Date: Fri, 14 Jul 1995 14:43:22 -0400 (EDT) From: Tech Support - Rick Subject: Re: your mail Well, think about this, we aren't the only ones flying on fiberglass tanks. There are certified tip tanks(Piper,Mooney, etc. ). the feds won't allow the gas to eat them. Epoxy is not uncommon to the aircraft fuel industry. Most of the solvents in auto gas have been flown in Long-EZ types using RAE. it was because of the auto fuels that Rutan started recommending the STP layups for the tank. Rick From: Marc J. Zeitlin Subject: Re: Fuel & Epoxy (fwd) Date: Fri, 14 Jul 95 14:46:15 EDT Lee D. wrote; >............. The only real safety issue with alcohol is >its ability to disolve parts of the fuel system like rubber hoses and >seals (and perhaps cured epoxy resin?). I've been planning (assuming I ever get to it) to use braided stainless steel teflon (I don't remember the Aeroquip # - maybe 606?) hoses for all my oil and gas lines. No rubber anywhere, if I can help it. As far as the epoxy goes, I seem to remember someone on r.a.h. posting that they had coupons of 2427 sitting in car gas for over a year with no problems, but for the life of me I can't remember who, when, or what. Certainly, more testing couldn't hurt. -- Marc J. Zeitlin E-Mail: marcz@an.hp.com Date: Fri, 14 Jul 1995 15:00:59 -0400 (EDT) From: Tech Support - Rick Subject: Re: Fuel & Epoxy (fwd) > steel teflon (I don't remember the Aeroquip # - maybe 606?) hoses for Steel lines are a REALLY BAD IDEA. There four or five Long/Vari EZ s that were forced to land off the airport because of the line's cracking due to fatigue. Almost everybody discontinued this use. Stet can you pull the issue numbers concerning this? Rick From: Marc J. Zeitlin Subject: Re: Fuel & Epoxy (fwd) Date: Fri, 14 Jul 95 15:06:20 EDT Rick C. wrote; > Marc Z. wrote: >> steel teflon (I don't remember the Aeroquip # - maybe 606?) hoses for >Steel lines are a REALLY BAD IDEA. There four or five Long/Vari EZ >s that were forced to land off the airport because of the line's cracking >due to fatigue. Almost everybody discontinued this use. Stet can you pull >the issue numbers concerning this? No, no, no! Not steel lines - stainless steel braids over TEFLON. These are flexible hoses - the braided line CAN'T crack. Only the teflon touches the fuel. I agree completely about solid steel lines - that's why Nat uses soft aluminum for the fuel lines in the cabin. -- Marc J. Zeitlin E-Mail: marcz@an.hp.com Date: Fri, 14 Jul 1995 16:35:22 -0400 From: Phillip.Johnson@Lockheed.on.ca (Phillip Johnson) Marc Writes > As far as the epoxy goes, I seem to remember someone on r.a.h. > posting that they had coupons of 2427 sitting in car gas for over a > year with no problems, but for the life of me I can't remember who, I think I wrote that on our mailling group. It was a friend of mine that did the tests. Phillip Johnson Date: Fri, 14 Jul 1995 16:40:44 -0400 From: Phillip.Johnson@Lockheed.on.ca (Phillip Johnson) Subject: Fuel & Epoxy Rick Wtites > Well, think about this, we aren't the only ones flying on > fiberglass tanks. There are certified tip tanks(Piper,Mooney, etc. > ). the feds won't allow the gas to eat them. Epoxy is not uncommon > to the aircraft fuel industry. > Most of the solvents in auto gas have been flown in Long-EZ types > using RAE. it was because of the auto fuels that Rutan started > recommending the STP layups for the tank. As far as I know Pipers, Mooneys etc use vinalester resins not epoxy which is why they are not affected. Boat, motorcycles likewise. I think its the low temp epoxies that suffer. BTW It's not only the fuels lines that should be considered. Any O ring or rubber gaskey also suffer. Phillip Johnson Date: 14 Jul 1995 13:55:55 U From: "Judd Stewart" Subject: Epoxy Fuel Compatibility Rick writes: ------------------ ------------------ 1) Is STP Safety-poxy? Piper, Mooney, Long-Ez types are flying something other than Hexcel 2427! Safety-poxy "HAS" the history of compatibility, I remember when Burt recommended it. I also remember people sloshing there tanks with some sort of compound. Safety-poxy works! 2427 is "NOT" Safety-poxy! 2)BTW- Has anybody got any idea's on how one would slosh the tanks of a completed Cozy. This thing is huge and to get full coverage one would have to a) fill the tank to the brim (expensive) or b) put in a couple of gallons and rotate the plane through all axis's. Judd-02 Date: Sat, 15 Jul 1995 23:54:42 -0400 From: NBalog@aol.com Subject: Stainless braid & teflon These lines have been used for years as aftermarket improvements on the rubber lines typically installed as OEM equipment on motorcycles; I've used three sets of these on 3 different BMW bikes and can attest to their ability to hold up to adverse conditions (heat, pressure) for years. Using these for fuel lines would seem to be ideal, if expensive, but what airplane isn't? -Norm