Frozen water in GFRP wing

On Apr 8, 12:48*am, Mike Oliver
wrote:
!

Blue Skies

*Expanding water (ice) if

not in a filled, enclosed compartment should not cause a problem..

Try putting a half filled jar of water in a freezer compartment overnight..
I think you'll notice a problem.

Wings are not made of brittle glass for a reason.


But your point does point to the probablility that the wing would fail
at a weak point, in this case probably the leading edge seam, that is
basically a reinforced epoxy/filler glued toggle that results in a
large squeeze out on the inside of the wing. The squeeze out would
make it very difficult for water to get into that seam. Now if water
got into the seam somehow or even between some of the squeeze and a
skin, and froze, IF anything would happen it would most likely be a
split in the leading edge. The borescope would show any delaminations
in the inner ply of glass fiber, where the water was trapped, by
appearing milky in color - borescopes give amazing clarity and detail
inside a wing. When viewing the inside of a wing, borescopes are
prefered because they have a remote screen where detailed inspections
can take place in real time. A simple video camera or film camera does
not allow this to be done, especially in tight areas. Carbon would be
more difficult to check for delaminations.

Actually I would be just worried about 3" of water in the leading edge
for several months, having seen the results and worked a bit on a
leaking Ventus water ballast tank.

But this is just speculation on my part. Off course the sailplane
should be taken to a composite repair shop, or manufacturing facility,
like the ones I have worked in, to have it checked out by a qualified
aircraft mechanic and inspector.

Mike

On Apr 8, 2:12*am, mike wrote:
On Apr 8, 12:48*am, Mike Oliver
wrote:

!

Blue Skies

*Expanding water (ice) if

not in a filled, enclosed compartment should not cause a problem..

Try putting a half filled jar of water in a freezer compartment overnight.
I think you'll notice a problem.

Wings are not made of brittle glass for a reason.

But your point does point to the probablility that the wing would fail
at a weak point, in this case probably the leading edge seam, that is
basically a reinforced *epoxy/filler *glued toggle that results in a
large squeeze out on the inside of the wing. *The squeeze out would
make it very difficult for water to get into that seam. *Now if water
got into the seam somehow or even between some of the squeeze and a
skin, and froze, IF anything would happen it would most likely be a
split in the leading edge. *The borescope would show any delaminations
in the inner ply of glass fiber, where the water was trapped, by
appearing milky in color - borescopes give amazing clarity and detail
inside a wing. When viewing the inside of a wing, borescopes are
prefered because they have a remote screen where detailed inspections
can take place in real time. A simple video camera or film camera does
not allow this to be done, especially in tight areas. *Carbon would be
more difficult to check for delaminations.

Actually I would be just worried about 3" of water in the leading edge
for several months, having seen the results and worked a bit on a
leaking Ventus water ballast tank.

But this is just *speculation on my part. *Off course the sailplane
should be taken to a composite repair shop, or manufacturing facility,
like the ones I have worked in, to have it checked out by a qualified
aircraft mechanic and inspector.

Mike

I would think that if the ice had done any damage to the laminate, it
would have left visible damage to the gell coat. That said, ultrasonic
is the definitive testing method for composite structures. A
transducer sends an ultrasonic pulse that reflects off the inside
surface and is picked up by the same transducer. Delamination will
cause reflections at points were there shouldn't be any. An
alternative to ultrasonic is to tap lightly with a plastic mallet;
delamination will change the pitch of the sound. A digital
oscilloscope and microphone would be another approach.

Tom