My recent fabric job

[PA1195]

Re: My recent fabric job

Hi Andy, this is Dave's thread so I'll be brief as possible. I've owned nine fabric airplanes, never hangared in Alaska, but none with Stewart's as the primary cover. I've been around a few that acquaintances have redone. All have had issues in isolated spots with delamination or bubbling. I don't know the cause but that may have been due to contamination during build. I have no direct experience with auto fuel and Stewarts.

Autofuel or a blend of that and 100LL is a reality for some owners. Having a covering that's potentially subject to compromise from that fuel would be a non-starter for me. The benefits of durability and lack of cold crack would be a positive aspect. I have a few lower wing inspection rings glued on with the Stewart's glue that's holding well in an experimental test versus the Stits glue.

Never had fuel associated problems with Randolph or ???

Gary

[N96337]

Re: My recent fabric job

I'll go out on a ledge here and say the "worm holes" are solvent popping. People are used to shooting solvent borne paint and the solvents evaporate quicker than water, so they aren't used to the timing and haven't learned the proper technique for checking when the paint is ready for the next coat, so they rush it and wind up with solvent pops. That's the most common problem I see when teaching people to use this system, other than contamination. With a solvent borne paint, you have a fairly strong solvent that works to help with a better bond as well as purging contaminants from the substrate as you lay that next coat of paint on. With a waterborne paint, the solvent isn't so strong, so any lack of tidiness or sloppiness in application will show up. It's like I always tell people, it's different, not difficult.

[PA1195]

Re: My recent fabric job

The popping and timing of events is what I've heard locally, plus possible contamination from products and procedures contrary to Stewart's recommendations. Sitting unprotected can introduce contamination Not my skill level.

Gary

[Guest]

Re: My recent fabric job

Dave,

I am sorry that you had this issue. I understand your frustration. I think you are right that this could use a mention in the manual. "think"? Well if you give me the lecture below in blue then you don't just think this (see red text above) you know it for sure and a heads up MUST be in the manual. We try to include everything in the manual, but sometimes I guess we take for granted that some things are common knowledge. All STC'd covering systems have been tested by the FAA to Part 23 or earlier standards that includes being resistant to AvGas. As with the other systems, Stewart Systems passed that test with flying colors. We are tested and certified for use with 100LL, Swift fuel, and the new Shell aviation gas. We have even tested our topcoats and primers with Skydrol and held up extremely well. We cannot test our products for auto fuel as there is no standard for it. There are literally hundreds of formulas for auto fuel in the US alone. It varies from state to state, county to county, and from one season to the next. Those formulas change constantly. It's not the alcohol that is the issue, it is the additives. Some of the injector cleaners and such are pretty much paint stripper. Auto fuel is a hazard to all covering systems. One formula in one area of the country may affect one system and not another, and in another area the reverse may be true. But no system is unaffected by all auto fuel. That is just the reality. A two part epoxy type topcoat will generally hold up fairly well, but the single part adhesives and primers generally will not. That is the issue. Our topcoat has never been affected by auto fuel yet as far as we know, but as with all covering systems, if the inside is exposed to auto fuel for a period of time it may be affected. Some auto fuels may affect it aggressively and others may not touch it. The safest thing to do is run AvGas. If lead is an issue for your engine, I would suggest Swift fuel. It is only slightly more expensive than auto fuel and it is a certified fuel that is safe for everything in your airplane including the covering. Another precaution that can be be taken is to topcoat the inside of areas that may become exposed to fuel with a two part epoxy paint such as EkoPoly. That can be done with a brush or roller if that's easier. That should be done regardless of the covering system that you use if you plan to run auto fuel. I have heard enough of this silly distraction (above in purple) please explain exactly how one does this on an Aeronca or Taylorcraft? I doubt it is even possible additionally is it in the manual? But having said all that, I have been handling tech support at Stewart Systems for about 1.5 years now and this is only second time I have seen any significant issues from auto fuel. It can happen, but it has not been a wide spread issue.

Andy

See colored/bold text above from you Andy and my comments that are underlined.

Dave R

[Ragwing nut]

Re: My recent fabric job

Dave,

I am sorry that you had this issue. I understand your frustration. I think you are right that this could use a mention in the manual. We try to include everything in the manual, but sometimes I guess we take for granted that some things are common knowledge. All STC'd covering systems have been tested by the FAA to Part 23 or earlier standards that includes being resistant to AvGas. As with the other systems, Stewart Systems passed that test with flying colors. We are tested and certified for use with 100LL, Swift fuel, and the new Shell aviation gas. We have even tested our topcoats and primers with Skydrol and held up extremely well. We cannot test our products for auto fuel as there is no standard for it. There are literally hundreds of formulas for auto fuel in the US alone. It varies from state to state, county to county, and from one season to the next. Those formulas change constantly. It's not the alcohol that is the issue, it is the additives. Some of the injector cleaners and such are pretty much paint stripper. Auto fuel is a hazard to all covering systems. One formula in one area of the country may affect one system and not another, and in another area the reverse may be true. But no system is unaffected by all auto fuel. That is just the reality. A two part epoxy type topcoat will generally hold up fairly well, but the single part adhesives and primers generally will not. That is the issue. Our topcoat has never been affected by auto fuel yet as far as we know, but as with all covering systems, if the inside is exposed to auto fuel for a period of time it may be affected. Some auto fuels may affect it aggressively and others may not touch it. The safest thing to do is run AvGas. If lead is an issue for your engine, I would suggest Swift fuel. It is only slightly more expensive than auto fuel and it is a certified fuel that is safe for everything in your airplane including the covering. Another precaution that can be be taken is to topcoat the inside of areas that may become exposed to fuel with a two part epoxy paint such as EkoPoly. That can be done with a brush or roller if that's easier. That should be done regardless of the covering system that you use if you plan to run auto fuel. But having said all that, I have been handling tech support at Stewart Systems for about 1.5 years now and this is only second time I have seen any significant issues from auto fuel. It can happen, but it has not been a wide spread issue.

Andy

Impossible to coat the inside of many wings after covering with wing tank installed. And just because it passed FAA regs does not remove you from liability. I have had Consolidated aircraft coatings give me all the material to recover an airplane be recover an airplane because of an issue and know of others that had material warranties by Airtech (in their early years). Materials are cheap if you consider your time in recovering an airplane.

[barnstmr]

Re: My recent fabric job

WOW - Never heard that about Stewarts. Now I know for sure I won't be using it. I've always used Randolph Nitrate-Butyrate and have been satisfied. Currently working a repair on a customer with Polyfiber. My first time working it. So far so good. You just have to be careful not to build up too thick on the polybrush. You can't sand it.

I have seen some nice looking Stewarts finishes. But I won't be trying it after seeing this.

[N96337]

Re: My recent fabric job

Impossible to coat the inside of many wings after covering with wing tank installed.

Yep, so coat the bottom of the tank bay before you finish. Put the bottom fabric on and shrink to 250, then brush, roll or spray (I sprayed) and install the tank. I was taught that way long before this system came along, on Polyfiber.

[N96337]

Re: My recent fabric job

The popping and timing of events is what I've heard locally, plus possible contamination from products and procedures contrary to Stewart's recommendations. Sitting unprotected can introduce contamination Not my skill level.

Gary

It's not a biggie....you should know how to check if the paint is ready for another coat no matter what system... you just gotta have some patience with a waterborne. Touch it with the back of your knuckle and when it's no longer transferring paint, but still tacky, it's ready. Not a big deal, but waterborne takes a bit longer to get to that point. All systems will introduce contamination if left unprotected.

[PA1195]

Re: My recent fabric job

Auto fuel tolerance aside it may be that using a new covering process brings change and risk. We (they actually) tend to forget how many planes and years it took to perfect whatever method. Plus there's lots of peer support available when questions arise for old time processes. This process is relatively new and the environmental safety factor is a plus. If it adapts to cold even the better for some of us.

I wonder if it can be made fuel resistant? Perhaps or perhaps not.

Where does the auto fuel enter the covering? Back, topcoat, or edge material?

I clean Polytone with charcoal lighter fluid when stained with no effect to the topcoat. Isopropyl will eat it. Simple Green barely touches some of the surface dirt. This I learned after forest fire smoke left a resinous coating that only a petro solvent will remove.

Maybe Stewarts is less prone to attracting stuff than Polytone. That would be good.

Gary

[astjp2]

Re: My recent fabric job

Actually the guy that was giving dave info about not having a standard for testing for autofuel is crap, there is an ASTM for automotive gasoline, I had to read the stupid thing when I was going to get an stc for my fuel valve. I just remember there was something about compatibility of materials, the gasoline needed to be tested to ensure that there were no adverse reactions when used that affected any part of the system. Crap, I may have to look it up...again

Crap, its on my other laptop..

[Edwin Otha]

Re: My recent fabric job

I think Stewarts is talking about a FAA spec. That would be something they would need to test to.
I don't use car gas so I don't know the problems first hand. I can say that all of my customers that have used car gas have had some kind of fuel related problem. Not vapor lock or blown-up engines like all of the fear mongers predicted, but leaky quick drains, gascolators, carburetors and premature aging on the flexible lines. Smells awful too.
I've used Stewarts and have had no issues, that stuff wears like a hogs nose. Used Blue River too, no problem if you read the book. A lot of these problems were akin to the change over from Grade A to Dacron fabrics, most people hated them until they learn how to use the product.
EO

[astjp2]

Re: My recent fabric job

That's funny because the FAA had me using the ASTM specs because they are an industry standard. My valve meets the WWV-35C spec. FAA specs are not stand alone when it comes to creating specs. Avgas meets an ASTM spec too, not an FAA spec. Spark plugs are required to meet a MIL. spec. etc.

[Guest]

Re: My recent fabric job

Yep, so coat the bottom of the tank bay before you finish. Put the bottom fabric on and shrink to 250, then brush, roll or spray (I sprayed) and install the tank. I was taught that way long before this system came along, on Polyfiber.

How do you do that with envelopes? or with the tank installed in the bay with the drag, anti-drag wires installed and going thru the tank, makes no sense John, what am I missing?

[Guest]

Re: My recent fabric job

Auto fuel tolerance aside it may be that using a new covering process brings change and risk. We (they actually) tend to forget how many planes and years it took to perfect whatever method. Plus there's lots of peer support available when questions arise for old time processes. This process is relatively new and the environmental safety factor is a plus. If it adapts to cold even the better for some of us.

I wonder if it can be made fuel resistant? Perhaps or perhaps not.

Where does the auto fuel enter the covering? Back, topcoat, or edge material?

I clean Polytone with charcoal lighter fluid when stained with no effect to the topcoat. Isopropyl will eat it. Simple Green barely touches some of the surface dirt. This I learned after forest fire smoke left a resinous coating that only a petro solvent will remove.

Maybe Stewarts is less prone to attracting stuff than Polytone. That would be good.

Gary

Hi Gary,

My gripe at least for is now is not that it reacts to auto gas but it is that they had not made that warning to me by any means prior to my "catastrophe".

I would have simply not used auto gas if I had been made aware.

Also I don't buy into the idea that avgas is no issue, but that is for later worries if at all.

All the rest of the talk about does and doesn't and how reduce risk are not meaningful to me because I would merely not have used auto gas.

As you point out it is an old problem.

Dave R

[PA1195]

Re: My recent fabric job

Yes I see your points Dave and agree there should be an obvious written disclaimer/caution prior to promoting or selling the product. Given the man-hours involved in recovering and the potential for risking customer satisfaction it's not acceptable.

I apologize for my tendency to walk around the subject but felt I should add some alternative observations before skewering Stewart's. It has the potential to replace other methods providing it can be made fuel resistant or better yet fuel proof as possible.

Local folks were not pleased at the bubbling and imperfections that developed after recovering. Fuel was not involved in those incidences as far as I know.

As a customer I'd not pay someone to use it at this point.

Gary