Stewart System Paint

[ak49flyer]

Interesting- I don’t think that info was in the manual when I was using the system 6-8 years ago. Haven’t ever heard of sealing with Ekopoly from the outside; would make me nervous about the ekofill adhesion. So I guess you’d seal the areas aft of the tank bay from the outside, and paint the inside when doing the topcoat…? (I agree it’s easy to do and takes no time, just had issues with the unprotected areas aft). Probably best to do the left side of fuselage and belly areas too, since those can get pretty saturated if a plane sits for a few days with an undetected leak…

[EdH]

Does anything say don’t use autogas or it could ruin the coating? Seems like this is a huge problem, especially since so many cubs and older planes use it these days.

Sent from my iPhone using SuperCub.Org

[jimboflying]

Which layer of the Stewarts system is being affected by the Mogas?

[Rob]

Interesting- I don’t think that info was in the manual when I was using the system 6-8 years ago. Haven’t ever heard of sealing with Ekopoly from the outside; would make me nervous about the ekofill adhesion. So I guess you’d seal the areas aft of the tank bay from the outside, and paint the inside when doing the topcoat…? (I agree it’s easy to do and takes no time, just had issues with the unprotected areas aft). Probably best to do the left side of fuselage and belly areas too, since those can get pretty saturated if a plane sits for a few days with an undetected leak…

I never read this either, but it makes total sense to me. As for adhesion, I can't imagine any problem, after all you already have the same products layering in the standard application, they are just in opposite sequence.
Agreed on the left fuselage, that is the only place I've ever had a problem on the 15 y/o finish on my cub. Leaky fuel selector. Peeled at the lower longeron, but I was far more disappointed with the fuel selector r&r than I was with the SS product.
As for vents and drains, I think they're a huge help. I feel like total saturation followed by a quick flash off is far less damaging than a chronic seep. My tank covers do not have the rubber doughnut, and my middle name is not Grace. I have spilled far more fuel in to my wings than I can remember, and have watched it rain out the back, but it's always dry a few minutes later and have yet to have a blister under the wings. Conversely, on the left fuselage I would have never know there was a leak if the paint didn't blister and peel, yet when I removed the inside panels the inside of the fabric was heavily stained blue. My fuel is typically loaded Rt tank Mo, and Lt tank Av.

All systems have a compromise, you just need to pick which compromise effects you the least and which positive attributes are most desirable to you.
I've been impressed with SS so far. So much so that last year I did a set of AG Cat feathers, as well as the tail of one of my Thrush' That airplane now has two corn run seasons on it and one fall through spring produce season on it. For comparison, prior to this, it was going through legacy systems to the tune of a new cover job every year. I know of no harsher life on a fabric system than this;

A) Caustic chemical baths on every flight
B) Pressure washing to remove said chemicals, and lastly
C) 24/7 outdoor storage in one of the hottest desert climates in the nation.

Take care, Rob

[Marty57]

Does anything say don’t use autogas or it could ruin the coating? Seems like this is a huge problem, especially since so many cubs and older planes use it these days.

Sent from my iPhone using SuperCub.Org

We address the issue of autogas in the same section as I indicated. The issue with autogas is often a regional issues. I have another fabric sample that I tested the same time, and from the same fabric swatch, as the sample in 100LL. It was first tested in autogas w/ethanol in Ohio and there was no issue with the sample. I placed a piece in CA 10% Ethanol fuel and the paint separated from the fabric in the matter of minutes. This is consistent with other issues I have had with autogas here in small engines; it destroys many carb parts if left in the engine for any length of time. I have no idea what is in CA fuel but it is pretty bad compared to other regions. Auto Gas, without ethanol, should be ok but it depends on the region. Auto gas today just doesn't have any national standards so it is impossible to have any fabric system resistant to all auto fuels across the country. In the case of the sample I tested, the top coat was unaffected by the ethanol based fuel; it was the bond between the fabric and the Ekofill where we fill the weave with EkoBond glue. Painting the inside of the fueltank bay, having adequate drain holes and grommets, and sealing fabric as we have outlined in our manual will prevent this debonding from additives that may be found in auto gas. When I teach fabric covering, I recommend making a couple 2' x 2' wood frames and covering them with fabric through the entire system, including top coat. You will not only learn how the paint behaves as you shoot it but you will have fabric painted that can be used for patching a damaged area. Relevant to this post, you will have fabric to test in your regional auto gas if you desire. In CA we have totally different auto gas in summer vs winter. We have no ethanol free auto gas available so it is a moot point for most aviation use but in other regions, I would want to know how my fabric reacts to auto gas; regardless of the system used. As a homebuilder, I trust the Stewart Systems but I am very leary of the auto gas available here in CA.

Marty57

[bob turner]

It used to have MEK in it. MTBE? It does eat stuff - the rubber hoses on my ‘65 Mustangs needs replacement at ten year intervals. Doesn’t seem to affect auto carbs (or indeed Strombergs).