Sign in to follow this  
Followers 0

KF fabric problems

9 posts in this topic

Posted

So, yesterday a local mechanic I found that had some knowledge with rotax and experimental aircraft came out to my hangar and was going to do a condition inspection. we took out the seat and was taking the airplane apart getting it ready for inspection and he tapped on the bottom fabric under the seat and it made a cracking sound, the dope and finish cracked but he didn't poke a hole in the fabric. He then put a light on the inside of the side fabric and one could see little pin holes of light, especially by the tapes. He then told me my fabric was junk and that my airplane was unairworthy and the fabric needed to be replaced before an inspection was signed off. I then asked him about a punch test with a Maule fabric tester and he said that those testers were inaccurate and that I just needed to replace my fabric before I killed myself. Another thing he said, was that since the paint had some ring worming that was another indication that the fabric was junk. 

My question is, is he right or just uneducated with light aircraft fabric?   The fabric is 27yrs old(I need to check the log books to be sure) and what kind of fabric isvmost likely to be on it, being it's a 93. And also is a Maule tester inaccurate like he's telling me. 

I dont mined having to recover if that's what I have to do, but I also don't have $$$ to spend on something that doesn't have to be done, at least not for a year r 2 

Thanks in advance          Jared 

Share this post


Link to post
Share on other sites

Posted

A maule tester is only an aid and not used alone to determine fabric condition. Your airplane likely has polyfiber, so the polyfiber manual rules as far as inspection. See appendix E and F

https://4dc8cf9a-0bab-40d5-bd6e-ca9b4967451d.filesusr.com/ugd/d66f5e_1ec5fa221f42471385a8ed2c97c69571.pdf

 

In general though ring cracks, or light showing next to tapes IS an indicator that the fabric likely needs help or replacement.

Share this post


Link to post
Share on other sites

Posted (edited)

The little pinholes in the fabric is a common problem in finishes. Generally means the fabric sealer was not applied to saturate the fabric well enough. Paint cracking (ringworm) usually indicates the paint isn't polytone (enamel cracks) or it was a heavy coat applied. Neither one indicates bad fabric although after almost 30 years it could be. Try the finger test, take your finger and try to push thru the fabric, the indentation should come back out in a short (less than a minute or two) time. If it does the fabric is most likely ok, if it doesn't then the fabric has lost its ability to stretch. If your finger goes thru the fabric then its in need of replacement.  Most newer A&P's aren't familiar with dope and fabric like us old codgers. Back then a lot of time was spent on fabric work and nowdays its covered briefly. First, identify what type system was used, Poly fiber, or one of the other systems that was available in '93.

Edited by Allen Sutphin
1 person likes this

Share this post


Link to post
Share on other sites

Posted (edited)

From reading the appendix  E and F, it seems to indicate that it is mostly/almost only UV from sunlight that destroys the fabric.  See the first paragraph in appendix F.  Most of our Kitfoxes and Avids are only outside when we fly them, so UV damage should be far less of a problem for us then for a plane sitting outside.  And unless you fly upside down a lot, the bottom is especially not likely to get a lot of UV exposure.  If he was talking about the top of the wings or the fuselage, maybe much more likely.  The appendix also talks about rejuvenating the paint to take care of the ringworm, so that alone should not disqualify the plane.  I would wonder how much he really knows about fabric.  By the way, if the inside of the fabric is pink in color, it's almost for sure poly fiber coating.  If the AnP is open to talking at all, I would gently try to get him to go over the info in afore mentioned appendix E and F to see if he will look at things in a more favorable light.  JImChuk

PS  you most likely have the 1.7 oz ultralight fabric on the plane.  That is what Kitfox supplied in their kits.  My first Kitfox 4 came with that lightweight fabric from Kitfox also.

Edited by 1avidflyer

Share this post


Link to post
Share on other sites

Posted (edited)

He only inspected the bottom and the side right be hind the left door. I pushed on the top of the wing and it was fairly tight. I do know the original Builder built the kitfox so he could fold the wings and put it in his garage so I'm pretty certain that it spent all of its life inside.  the guy I got it from got it so he could keep it in his barn

Edited by FireFoxIV

Share this post


Link to post
Share on other sites

Posted

If it's the 1.7oz than it would be tested with less weight than 56lbs right?

Share this post


Link to post
Share on other sites

Posted

The mechanic said he thought it was ceconite fabric not poly-fiber because of the blue tint from the inside

Share this post


Link to post
Share on other sites

Posted


I had a challenger with Blue fabric and painted with Superflight and it was the same way. Paint was cracking all over. I was told push your thumb in hard and if the dent comes back out the fabric is ok

Share this post


Link to post
Share on other sites

Posted

Thank Tjay I'll try that. I'll  be going to the airplane this week end and do some more testing and probably run fuel additive though the engine, because I have a feeling I won't be flying for a couple more weeks

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0