Yes, Chris's last paragraph is VERY relevant.
Try to avoid making access holes anywhere near the main spar. I don't know
how they build Astir wings, but if the designer used spar caps and a web,
then obviously there will be additional layers of glass in this area to hold
everything together: Not an area to penetrate, with a random hole or two!
Gary
From: aus-soaring-boun...@lists.internode.on.net
[mailto:aus-soaring-boun...@lists.internode.on.net] On Behalf Of Chris
Runeckles
Sent: Monday, 28 October 2013 11:40 AM
To: Discussion of issues relating to Soaring in Australia.
Subject: Re: [Aus-soaring] integral wing water tanks
Stuart
As John says above, don't get conned into sloshing the leaky tanks, as
that solution is temporary at best, as the resin used for sloshing will not
bond to the tank due to dirt and contamination inside the tanks.
As Mike says opening the tank, cleaning and sealing the tank is the only
correct method.
One trick you can try on an Astir is to put a little pressure on the tank
(125 mm water gauge, the same as AD 165) and use soapy water and try and
find the leak, Astir tanks are not very long and I have found one leak on
the end rib around the front drag pin mounting, which had become porous some
how., or use the trick Mike suggests with the water and stethoscope , you
can usually locate the area of the leak with in a 100 mm radius.
If you manage to find the leak, open up the tank with a oval hole just big
enough to get your hand in , clean the tank thoroughly with scrubbing brush,
wire brush, or what ever it takes to clean the scale etc out, wipe
thoroughly with acetone, stay away from any areas that have polystyrene
though,(Astirs are OK, mainly cirrus.) with chemicals that might dissolve
the Styrofoam as some manufactures use this in fillets etc. or on the
leading edge as seal the wing halves before joining.
then paint liberally with
http://www.duram.com.au/productdetail_var11var21var33 Duram 195 - Liquid
Polyurethane Waterproofing Membrane, as far as you can get around the
opening , but keep a little area around the cut hole clean with masking tape
so a joggle can be fitted after the sealer has set which takes a couple of
days , don't forget to seal the back of the joggle with the Duram, glue in
the joggle and conduct a standard repair and close up the wing.
I have never failed to fix a tank by this method, but it is time consuming
and messy, expensive if not a labour of love ! I fixed a standard Cirrus
once that took 6 holes per wing as I sealed the whole tank, and there are
baffles in the tank which means holes each side of the baffles !
Also the obvious must be said, that you are putting holes in the D box in
the wing, which is a structural repair, and should only be tackled by a
authorised repairer with a Major repair rating in FRP.
Kind Regards
Chris Runeckles
On Mon, Oct 28, 2013 at 6:32 AM, John Orton johno...@gmail.com wrote:
Stuart et al,
Mike is right. I have seen the inside of tanks where they tried to seal them
by pouring in a resin mix to coat the inside andget it to seal. It was a
mess with sheets of resin peeling away from the inside skin.
I have leak detected several tanks using the method Mike describes and found
that often the leak is in a corner at the end of the tank or where there is
a baffle attached to the skin i.e. at a discontinuity.
Regards,
John Orton
On 28 October 2013 06:04, Mike Borgelt mborg...@borgeltinstruments.com
wrote:
Stuart,
The only rally satisfactory way I have heard of is the method invented in WA
many years ago. Put a little water in the tank, put a little suction on it
and listen for the air bubbles with a stethoscope. You need to roll the wing
around to to get the water over the leak.
Then use a hole saw, cut a hole and do a standard repair.
Nowadays you may be able to put a little camera in the tank with a light to
see what needs doing through a smaller hole first.
Mike
At 09:12 PM 27/10/2013, you wrote:
Hi all,
Can anybody recommend a product and method to seal an integral wing tank in
an Astir cs.
Cheers
Stuart
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