Re: UV damage

Mike Dwyer

Many years ago I left an unprimed piece of fiberglass in the Florida sun as a test. After a while the resin went away leaving the white glass on the surface. I assume the resin basically evaporated. The elevator slot is a critical area, kind of like a mini wing spar so I'd be real careful there. Asking another builder if you should use a part that you know to be previously damaged is just trying to find someone else to help you justify a bad decision. If your building a tri-Q then there is less stress on the canard and you might get away with it. Putting a new lamination on top of a contaminated layer is at best a waste of time. Try laminating two plys together with one piece of glass exposed to one drop of water and see what happens...

I calculated that the Q200 canard has the equivalent of 4G on it when loaded to gross on the ground, plus it is supported by the wing tips. Load a Cessna to gross (not even 4X) and pick it up by the wing tips some time, you'll be buying some new wings. In other words your stress test may have been ok for flight loads but I seriously doubt you tested for landing loads.

There are old pilots and there are bold pilots... but there are no old, bold pilots.

Mike Q200 N3QP


To: Q-LIST@...
From: quickieaircraft@...
Date: Tue, 12 Jul 2011 20:34:28 +0000
Subject: [Q-LIST] Re: UV damage

Does anyone know if there is a decent way to inspect for UV damage once
primer and finish is applied? I know...there shouldn't be any damage
through the paint and primer, but...well, I think most of us still
store our composite planes indoors just in case.

--- In Q-LIST@...<mailto:Q-LIST@...>, "Allan
Farr" <afarr@...> wrote:

Thanks Mike
Actually, I'm less worried now. The main area of UV damage (or dry
lay-up) are the elevator slots (t/e of canard), so it seems to me that
at worst I will just have to replace that (or maybe add an extra ply of
bid on top?). I will get a local Varieeze builder to have a look. What
brought this about is finding that the a/c doesn't have the black UV
protection, just a yellow (ochre?) undercoat/filler, with gloss white
on top. It's possible these paints have UV protection built in, but it
would be good to know for sure as UV here in NZ is about as extreme as
it comes (we live under a hole in the ozone). The a/c has previously
had a stress test on the canard & wing which it passed with no
"cracking or popping" & with the wings returning to their original
positions, so I presume it must be basically sound.
Allan F

----- Original Message -----
From: Mike Dwyer
To: Q-LIST@...<mailto:Q-LIST@...>
Sent: Tuesday, 13 March 2007 12:39
Subject: Re: [Q-LIST] UV damage

That is absolutely UV damage. I would scrap the plane as you don't know
how much delamination/damage was done to the underlying foam. Your life
is worth more than it would cost to build new parts.
Mike Q200 N3QP 1000+ hours

Allan Farr wrote:
Some of the visible fibreglass on my plane (cockpit, elevator slots
on canard, etc.) shows a lot of cloth & very little resin. Does anyone
know if this is likely to be UV damage, or perhaps just a dry layup?
Also, I would like some info on manufacturing the elevator trim system,
is this available?
Allan F.
Q2 Rev 99% completed by others.

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