SB #7 Structural tests?

[jonstark]

SB #7 refers to structural tests the manufacturer was to perform to ascertain whether the strength of epoxy using microballoons would be comparable to that using cotton flox. I can't find any further reference to these tests and wonder whether they showed acceptable strength for wing applications using microballoon thickened epoxy.

questions...
1. Is there a visual way to tell if the epoxy used in wing construction was thickened with flox or microballoons?
2. Is there any reference to the test results?
3. Is a wing made with microballon thickened epoxy acceptable?

thanks!
jon

[n85ae]

Microballons are a non-structural sandable filler, you would not use them to build
a wing, or other structure. If you have a wing built with them, it would not be
airworthy.

Regards,
Jeff Hays

[jonstark]

If you have a wing built with them...

How can I tell?

jon

[n85ae]

You could probably see the cotton fibers in the cured joints with magnifying
glass, if you have a kids cheap microscope you could surely see the fibers
with it.


Here's a link to some info on fillers:

http://members.eaa.org/home/homebuilders/building/composite/5Part%202%20Basics%20of%20Composite%20Construction .html

Here's a link, which seems to say it's ok, BUT I would not build a wing with them:

http://kitfox.lazair.com/Service_Letters/sl21.htm

John McBean at Kitfox could probably say yes/no to use on a Kitfox.

Regards,
Jeff

[jonstark]

Your second link is key. It refers to a batch of serial numbers rather than the SB which calls out a period of delivery dates that might have been delivered with balloons in lieu of flox.

I fell within the delivery dates but now find this kit was outside the serial number batch.

Whew!

Thanks for the info.
jon