Discussion in 'Pitts' started by cwspilot, Mar 13, 2018.
Has anyone used the Maule fabric punch tester? What should fabric on the Pitts test out to?
About 5 years ago, my first starduster inspection the mech had one. Don't know if he had ever used it judging from the way he handled it. Checked oK of course. At the time my hanger mate had some old t-craft frames. They were older than Methuselah's dog but not cotton. I asked him to check one of them as they were rags. Checked OK. I was not impressed. My opinion was if it failed it would be obvious to the eye. But I can stand to learn something.
80 lbs new for grade A cotton, 70% used, its used if its been installed on the plane.
Polyfiber is much stronger, but still test to 56 lbs.
The Maule will leave an indentation that is all most gone in a few days. Old paint may crack or ringworm. Test on upper surfaces in the darker paint. I,ve only have failures in Cotton, never Dacron but not saying it cant.
If you look Cotton and I believe Razorback (fiberglass cloth based old system) are the ones that are “punch tested”. From all the ceconite and stits books I’ve read I have never seen them give a punch test method as a way to test airworthiness. Please share info if you indeed found info where they recommend a punch test.
Manual says its an aid. I'd much rather tell a lawyer I used a tester than I pushed it with my knuckle to test airworthiness. Like I said, never tested a bad Polyfiber yet, only cotton. Most of my customers don't want me to cut a 1" strip out of the plane to check its strength.
So to me its a reasonable test to make sure the fabric is good without any damage to the fabric and gives me some assurances.
Appendix F from polyfiber manual pg 103
The IA can use a Maule Fabric Tester
on the bare fabric as an aid to see if
there is UV damage.
Warning: AC 43.13 - 1B states
that a Maule Tester is not
approved for determining
airworthiness; it is only an
aid. Also Maule Testers only
give an accurate reading on
bare fabric. It does no good
to “punch” painted fabric;
you are measuring the com-
bined strength of the paint and
fabric. The FAA only cares
about the fabric. To use the
Maule, push until it reads 56
pounds; no need to push fur-
ther and punch a hole in the
fabric unless the IA is seeking
additional business repairing
your unnecessary holes.
The important point is bare unpainted fabric! Painted in some cases will aid failure. If it does then remove the paint and retest, good chance it will pass.
Thanks for the input everyone. Much appreciated!
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