On Fri, 21 Oct 2005 05:38:56 -0400, Michael Horowitz
wrote:

What pressure is a coated fabric subjected to to determine if it has
deteriorated? - Mike

mike
I have seen a guy try to repair a wing that his arm went through just
leaning near it.
you gotta stop pussyfooting around with fabric.
make your hand into a "bird" walk down the side of the aircraft and
whang that finger into the fabric as hard as your finger can stand.
if it ever goes through you just saved yourself from a midair
breakup.
aircraft fabric in serviceable nick is pretty damn resilient. there is
a video somewhere of a kid at oshkosh bouncing on a fabric wing like a
trampoline. I'm pretty sure it actually didnt damage the wing.

next time you are in flight you should rest your hand against a
section of fuselage fabric. you'll be truely surprised at how much it
moves around.

fabric safety isnt about "its just 1 pound over the minimum strength
so I'll get another 3 months and 2 days out of it" its about making
sure that in turbulence at VNE in a steep turn nothing even looks like
coming adrift.(thats what you need to be testing for)

if you are buying an aircraft and the owner hasnt the confidence that
it will withstand a robust "birding" then that guy has just admitted
something and you should turn tail and walk away.

I get asked on occasion about fabric testing since I fly a fabric
covered aircraft (among a field which is overwhelmingly aluminium) and
I demonstrate a robust birding to the point that the guy winces at the
possible consequences. I'm actually only testing the Stits fabric to
about half it's strength. If it ever breaks he's just saved my neck.

have a look in AC43-13 at the table on page 2-2.
56psi if vne over 160mph
46psi for slower aircraft.
....but dont kid yourself that those figures may always be safe.
Stealth Pilot