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Thread: Stewart Systems - Is top coat req'd?

  1. #1
    kevin50D's Avatar
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    Default Stewart Systems - Is top coat req'd?

    Need to do some fabric repairs on my 22/20, it's currently covered and finished with Stits. I've used the Stits rejuvenator in the past, but now I would just like to replace a few area of fabric completely. Areas of concern are: lower surface wing roots (under the gas tanks) and the top of fuse directly behind the windshield. My dad and I have experience covering with Stewart's and prefer it over Stits. The plane is approaching complete restoration (ground up rebuild & recover) in a couple years and I would like to extend the current cover's life until then. I'm fine with covering thru primer and would prefer not to top coat the repairs (Stewart's top coat is 2-part).

    My question is does the Stewart's need top coat to be legal under their STC?

    Sent from my SM-G950U using Tapatalk

  2. #2

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    Default Re: Stewart Systems - Is top coat req'd?

    Revision 21, September 2006, of the Poly-Fiber Procedure Manual No. 1 STC SA 1008WE allows only Poly-Tone or Aero-Thane or Ranthane (Ranthane now approved 2006!) topcoat paint over the fabric-covered components of certified aircraft. This is a major change to the STC. Use of any other topcoat paint over fabric will void the STC. The old rule that the STC was valid only “up to the silver” and that any available topcoat paint could be used has changed. The increasing use of brittle automotive polyurethane paints over the years has caused enough cracking and delamination to cause the FAA to rethink approving untested topcoat paint over fabric. Failed topcoat paints expose polyester fabric to sunlight and UV damage. Poly-Tone, Aero-Thane and Ranthane have long service records over fabric as well as established test data on file with the FAA. Additionally, both paints have an FAA Parts Manufacturing Authority (PMA) which allows their application on certified aircraft. This has no effect on the non-fabric components. For instance, a J-3 Cub must have only Poly-Tone or Aero-Thane over the fabric parts, but you could use enamel or anything else over the metal struts, cowls, doors, etc. The key word is FABRIC. Experimental aircraft are not bound by these changes; however, we do recommend using products with a known track record with proven procedures on fabric.
    Fly safe fly low fly slow

  3. #3
    Stephen's Avatar
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    Default Re: Stewart Systems - Is top coat req'd?

    My answer from Stewart originally came from Jason a few years ago. Finish Stewart's as per STC but, you can minimize the Stewarts finish coat and switch to any approved finish you desire. A Stewart primer coat may be an acceptable finish and seems reasonable but, I'm not sure. I have used Polytone for my finish for my plane's finish for years but, make sure I state that I have complied with the Stewart STC. According to Doug and Dan any finish will adhere to their Ekospray or primer. I've had to match finish on different planes after using Stewart's numerous times one has been in Alaska for years and has no problems.

    esk,

    I don't see how Polyfiber's requirements applies when you are using Stewart's system, which is approved to be put over Polyfiber. I understand Polyfiber's STC is not approved over other products and Polyfiber requires when using their process you must use their finish. But, this patch project would be according to Stewart's STC. My understanding according Stewart brothers advice is any approved finish is acceptable once you comply with their STC. At least it was unless the new owners changed the STC.
    Last edited by Stephen; 04-08-2018 at 07:25 PM.
    "You can only tie the record for flying low."

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    kevin50D's Avatar
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    Default Re: Stewart Systems - Is top coat req'd?

    For clarification, I would not be applying any new top coat, so the Poly Fiber revision referenced above does not apply.

    I didn't convey my question very well, is Stewart's system legal with no top coat? So it would be finished thru primer and that's it.

    Sent from my SM-G950U using Tapatalk

  5. #5
    Gilbert Pierce's Avatar
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    Default Re: Stewart Systems - Is top coat req'd?

    The Polyfiber STC has not been changed. They just changed in the instruction manual requiring Polyfiber top coats.
    You can follow the older instructions manual and use aany top coat you like. Just site that manual in the paperwork.
    We got this interpretation from the FAA fabric expert who manages the fabric STC’s.
    Last edited by Gilbert Pierce; 04-08-2018 at 07:21 PM.

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    Stephen's Avatar
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    Default Re: Stewart Systems - Is top coat req'd?

    Quote Originally Posted by Gilbert Pierce View Post
    The Polyfiber STC has not been changed. They just changed in the instruction manual requiring Polyfiber top coats.
    You can follow the older instructions manual and use aany top coat you like. Just site that manual in the paperwork.
    We got this interpretation from the FAA fabric expert who manages the fabric STC’s.
    Sounds like Polyfiber made a marketing decision. I've seen unrepairable badly cracked finishes on factory painted Maules.

    I don't think there is a better glue for patching than Stewart's and the eko products work fine but, I don't care for their top coat. I finish through their primer then spray other approved paints.
    Last edited by Stephen; 04-08-2018 at 07:37 PM.
    "You can only tie the record for flying low."

  7. #7
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    Default Re: Stewart Systems - Is top coat req'd?

    I've seen a few "Eco Gray" patches flying around over the years. I've had a few myself and noticed some tendency to fisheye on the two spots that were not topcoated within a year. Could have been anything though. It s handy to wipe a spot of Eco bond then dab on the Eco gray from a rock strike on the belly or gear until a more convenient time for a pretty repair can be made.

    legaly to be in compliance I think the topcoat is required.


    Rocket

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    Administrator Steve Pierce's Avatar
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    Default Re: Stewart Systems - Is top coat req'd?

    Quote Originally Posted by kevin50D View Post
    Need to do some fabric repairs on my 22/20, it's currently covered and finished with Stits. I've used the Stits rejuvenator in the past, but now I would just like to replace a few area of fabric completely. Areas of concern are: lower surface wing roots (under the gas tanks) and the top of fuse directly behind the windshield. My dad and I have experience covering with Stewart's and prefer it over Stits. The plane is approaching complete restoration (ground up rebuild & recover) in a couple years and I would like to extend the current cover's life until then. I'm fine with covering thru primer and would prefer not to top coat the repairs (Stewart's top coat is 2-part).

    My question is does the Stewart's need top coat to be legal under their STC?

    Sent from my SM-G950U using Tapatalk
    I don't know either and don't have the manual close by. ...i have two patches on my brothers Clipper and looks like it did when I brushed it on. Why would you want to recover those areas? I have seen the paint etc crack and look bad.

  9. #9

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    Default Re: Stewart Systems - Is top coat req'd?

    Quote Originally Posted by Steve Pierce View Post
    I don't know either and don't have the manual close by. ...i have two patches on my brothers Clipper and looks like it did when I brushed it on. Why would you want to recover those areas? I have seen the paint etc crack and look bad.
    There was a good discussion about a similar subject over on Supercubs.org. I have copied my post here with the YouTube url.
    The video may shed some light on this topic too.

    Found a video about inspection and repair using Stewart Systems. Has a good explanation as to what is a major repair, and if it is a minor repair, the official position as to using the Stewart top coat HAS changed! You CAN use the original topcoat over the Stewart glue and Ekofill IF it is a minor repair. This is a really good video about inspecting and repairing all systems with Stewart’s. Worth your time. https://www.youtube.com/watch?v=EIt5...ature=youtu.be


    Sent from my iPad using Tapatalk

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    Default Re: Stewart Systems - Is top coat req'd?

    I get “video not found” when I click the link.
    "Good judgement comes from experience, and experience comes from bad judgement." - Fred Brooks

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