Fabric Covering Test

[PANS]

Hi Folks,

I bought a Kitfox 5 and I need to know if the covering is good for flight. The installation looks pretty good, however, during a refueling, incidentally I made a small hole in the fabric over the wing.

I researched in the internet and I found a Maule tester and a Quicksilver tester. Considering the Kitfox is a ultralight category aircraft, what tester is enough to allow me to fly? Someone can help me?

Thanks a lot!

Marcio Pans

[Norm]

Use the Maule tester. The Kitfox may fit in your Ultralight catagory but it a 100mph plus aircraft and should be tested using the Maule tester.
If you put a hole in the fabric accidently it sounds like your fabric is not acceptable for flight. Do not take a chance. If the fabric starts to peel you have no chance for survival. This is a video of the fabric on my airplane before recover. It peeled easily. Fabric that is good can not be ripped like this.
https://www.youtube.com/watch?v=Z5eXg-Ou1L4
Good luck
Fly safe.

[PANS]

Hi Norm,
Thanks for your reply.
Do you know how the Maule tester works (schematic drawings)?
I would like to build by myself a similar tool to test my airplane (in my country is not so easy to find and buy a Maule tester).
Thanks,
Marcio Pans

[Dave S]

Marcio,

There is a policy reference the US FAA publishes which you might find useful regarding fabric evaluation. It's a + 4 megabyte file so I will include the link here. It has a section on evaluating fabric and the Maule tester.

https://www.faa.gov/regulations_poli...a/ama_Ch03.pdf

There is information on fabric specifications and how the Maule tester works - it's basically a probe which is designed to measure how much pressure in Pounds per square inch, is required to punch a hole through the fabric - things like that can be calculated and designed.

One of the things that is a problem with fabric testing is we would like to have a purely empirical method - that does not exist, even the Maule tester is not an approved testing device or method for normal certificated aircraft. It is just a helpful tool. In reality, other factors need to be considered such as knowing the history of the plane, how old the fabric is, does the covering have other issues than strength, what kind of fabric is it, how heavy the fabric is, how the plane was stored (hangared or outside), did the original covering comply with the manufacturers requirements - on that last point, the video Norm put on the list shows a covering job that ripped easily and was not properly assembled in the first place because a UV coat was apparently missing.

I have seen 20 year old Poly Fiber covered aircraft that are as sound as they were when new.

I have also seen some really wierd covering products such as a short lived product called "Razorback" which was a fiberglass cloth covering system that just did not work out.

Another thing about the Maule tester - OK - one spot passes the punch test - that is only one spot - what about the rest of the plane - was the original covering job done with a uniform coat of UV protection or is it spotty? Is the belly different than the top of the wing? If I understand the punch test correctly, I believe it relys on removing the paint and coats of material on the fabric so only the fabric is being tested - paint might make it seem stronger than it is.

Sorry for going on so long; but, the answer might not be as easy to figure as we would like.

Another good read is the section on fabric from the FAA's Advisory Circular 43.13 2B dated 2008 (note that there is a 1B which is obsolete dated 1998)

Advisory Circular 43.13 2B is a huge document and you can get to it by googling it up.

[PANS]

Hi Dave,

Thanks for your clarifying info. I just downloaded the FAA document.

You know, my Kitfox 5 received a new dacron covering 7 years ago, it was applied the silver UV protection and it was always hangared. So everything looks ok. My point is that it suffered too easily, in my point of view, a damage (small hole) in the upper part of the wing. As it was not me that covered the plane, I am a little bit concerned about it.... maybe too much, but safety is safety.

I will study the material and find a way to test the fabric. You helped a lot!

Thanks again!

[Dave S]

Marcio,

Maybe an addittional item to consider. Regarding the small hole in the upper part of the wing......might be worth thinking about how it occurred.

For what it is worth, I embarrassed myself by dropping a screwdriver, point first of course, when I was doing a condition inspection - so I ended up with a puncture hole......since it was a sharp object - didn't take much to penetrate so I glued a grommet on the bottom and called it a "drain hole"...made another one on the other side so it didn't look like a mistake

There is a huge difference between a sharp edge or point contacting the fabric and a blunt object - fabric can't take much from a sharp object...if the small hole in the upper part of the wing was made by a blunt object or a sharp object - I would evaluate it differently. If the hole was made by a smooth object that's a concern, while I'd expect a sharp object to easily make a hole on good fabric.

Take care & let us know what you find out. You are right - good to be sure.

[Norm]

Hi Marcio
I was out today flying my newly rebuilt KitFox and just got a chance to check posts. Dave pretty much covered all the info your after. Not much for me to add. You can search the net and youtube to get more info. I think I saw someone using a tester on one video. Do a search and you will find a lot of info. The fabric may be only 7yrs old but how much time did it spend outside?
Make sure you are safe.
BTW a local club has a tester you could borrow.

[avidflyer]

Here is a link to fabric testing and such that may ease your mind. Personally, if the fabric/finish looks good and it's spent nearly all of the last 7 years hangared I probably wouldn't worry about it. JImChuk
http://eaaforums.org/archive/index.php/t-4447.html

[PANS]

Thank you all, guys!

By the way, I talked also with Mr John McBean (kitfox Aircraft) and he suggested me to use the Polyfiber Manual as a reference for testing.
Any of you has this Polyfiber Manual? I couldnt find it in the net.

Thanks again,

Marcio

[Dave S]

Marcio,

I don't know if John has this book - I don't see it in the kitfox catalog; however, If you go to the polyfiber website, they sell it for $10 US + shipping and handling.

Here is the link to the page - the book is titled "how to cover an aircraft with the polyfiber system" I can verify that the book is excellent, extremely practical and thorough. I have one but I think I'll keep it

http://www.polyfiber.com/info/index.htm

The PF website also has a list of US and international dealers - Argentina may be an easier buy for you.