How does a Maule tester work?

There are different minimum pressures for different MAX airspeeds of the
aircraft.
A Stearman will have a different requirement than a Cub.
i'll try to find that data and post it.



Michael Horowitz wrote:
Carl - the reason I'm asking is that the covering and the engine are
the two biggies when looking to buy. We can get metrics on an engine,
and we know how to evaluate it, but it's not so clear cut with the
fabric.
The purpose of my pre-pre-purchase inspection is to weed out those
candidates I don't even want to get to the pre-inspection stage, so
I'm trying to be as independant of the A&P as I can.
OTOH, asking him to have _his_ A&P do the test certainly has merit.
- Mike


Carl Ellis wrote:


Mike -

I believe that if the fabric tears at any pressure it's a no go. The Maule
tester is just one tool to use to determine fabric condition. As far as I
know the tester is not an FAA approved test but is rather a somewhat
subjective evaluation tool.

There is a whole thread on this on the Taylorcraft Forum.

I would ask the seller to have his mechanic do the test and be there while
he does it. Off the cuff I'd say walk away if the dope is cracking below
50 lbs but I'm sure that a more knowledeable person has a better feeling
for this.


- Carl -




On Fri, 21 Oct 2005 05:43:48 -0400, Michael Horowitz wrote:


Carl - is 80 psi the go/no-go point?
How do you work around the seller's understandably irritation at the
tester's hurting the surface? - Mike



Carl Ellis wrote:


Mike -

The Maule tester is essentially a spring loaded rod in a tube. The rod has
a rounded end. The rod is placed against the fabric and pressure applied
to the tube which compresses a spring. There is a scale on the side of the
tube with graduations from 10 to 80 lbs in five lbs increments (if I
remember correctly). You might be able to find a picture in Aircraft


Spruce, Wicks, or other catalog.

New fabric will stretch with applied pressure all the way to 80 lbs. A
small dimple will be left in the fabric which will disappear completely
after an hour or so. Older fabric will probably experience cracking of the
dope (you can hear it) way before 80 lbs due to the plasticizer hardening.
On my previous Taylorcraft this happened at 65lbs (1977 covering). These
cracks will appear as ring worm and should be sanded down to silver and
repainted as light may degrade the fabric through the cracks.

If you are testing a prospective airplane the owner will probably be
annoyed if you use the tester and leave ring worm all over his baby.

Before selling my aircraft I had the test done. We did one or two areas to
determine where it cracked, then backed off 10 lbs for the next 30-40 test
locations. We indicated the lower number in the log book.

Hope this helps,

- Carl -

Look in AC 43.13-1B for fabric testing parameters.

--
Cy Galley - Chair,
AirVenture Emergency Aircraft Repair
A Service Project of Chapter 75
EAA Safety Programs Editor - TC
EAA Sport Pilot

wrote in message
...
There are different minimum pressures for different MAX airspeeds of the
aircraft.
A Stearman will have a different requirement than a Cub.
i'll try to find that data and post it.



Michael Horowitz wrote:
Carl - the reason I'm asking is that the covering and the engine are
the two biggies when looking to buy. We can get metrics on an engine,
and we know how to evaluate it, but it's not so clear cut with the
fabric.
The purpose of my pre-pre-purchase inspection is to weed out those
candidates I don't even want to get to the pre-inspection stage, so
I'm trying to be as independant of the A&P as I can.
OTOH, asking him to have _his_ A&P do the test certainly has merit. -
Mike


Carl Ellis wrote:


Mike -
I believe that if the fabric tears at any pressure it's a no go. The
Maule
tester is just one tool to use to determine fabric condition. As far as
I
know the tester is not an FAA approved test but is rather a somewhat
subjective evaluation tool.

There is a whole thread on this on the Taylorcraft Forum.

I would ask the seller to have his mechanic do the test and be there
while
he does it. Off the cuff I'd say walk away if the dope is cracking below
50 lbs but I'm sure that a more knowledeable person has a better feeling
for this.


- Carl -




On Fri, 21 Oct 2005 05:43:48 -0400, Michael Horowitz wrote:


Carl - is 80 psi the go/no-go point?
How do you work around the seller's understandably irritation at the
tester's hurting the surface? - Mike



Carl Ellis wrote:


Mike -

The Maule tester is essentially a spring loaded rod in a tube. The rod
has
a rounded end. The rod is placed against the fabric and pressure
applied
to the tube which compresses a spring. There is a scale on the side of
the
tube with graduations from 10 to 80 lbs in five lbs increments (if I
remember correctly). You might be able to find a picture in Aircraft


Spruce, Wicks, or other catalog.

New fabric will stretch with applied pressure all the way to 80 lbs. A
small dimple will be left in the fabric which will disappear completely
after an hour or so. Older fabric will probably experience cracking of
the
dope (you can hear it) way before 80 lbs due to the plasticizer
hardening.
On my previous Taylorcraft this happened at 65lbs (1977 covering).
These
cracks will appear as ring worm and should be sanded down to silver and
repainted as light may degrade the fabric through the cracks.

If you are testing a prospective airplane the owner will probably be
annoyed if you use the tester and leave ring worm all over his baby.
Before selling my aircraft I had the test done. We did one or two
areas to
determine where it cracked, then backed off 10 lbs for the next 30-40
test
locations. We indicated the lower number in the log book.

Hope this helps,

- Carl -

Cy -
When an A&P does a test, does he have to be prepared to repair any
damage he might do i.e. crack the paint or punch a hole? - Mike

"Cy Galley" wrote:

Look in AC 43.13-1B for fabric testing parameters.

The beauty of the Maule tester is that there isn't a hole IF the fabric
passes. There can be some very minimal paint damage which is easily fixed.
If the hole punches below the minimum level, then the fabric should be
removed and replaced as it doesn't meet safe strength levels. If one
continues the test to a higher level until it punches a hole, just a drop
of paint to fill the hole can be used.


"Michael Horowitz" wrote in message
...
Cy -
When an A&P does a test, does he have to be prepared to repair any
damage he might do i.e. crack the paint or punch a hole? - Mike

"Cy Galley" wrote:

Look in AC 43.13-1B for fabric testing parameters.