Ammonia gas works just as well, less expensive and has a range
of sniffers available. Just as hazardous but probably not as harmful in
controlled amounts.
John Cox
From: Lancair Mailing List
[mailto:lml@lancaironline.net] On Behalf Of Jim Nordin
Sent: Sunday, August 17, 2008 10:41 AM
To: lml@lancaironline.net
Subject: [LML] Detect a leaking wing on IVP
Empty the tank of fuel. Flush the inside of the
tank with Freon (don’t let the FEDs know), pressurize it a tiny bit, seal
it, then use a “sniffer” to detect the very smallest micro leak.
Flow plenty of air over the wing areas for a while to remove residual Freon
pockets before your search begins. Freon’s molecular size (critical
dimension is about 5.3 angstroms) is close to pentane (6 angstroms I think I
remember) which means, if you can flow pentane, you can flow Freon. So if you
find a leak using a sniffer, you might have a gasoline leak there too. Hey, I
might be wrong about the numbers … it’s been a long time since
using these dimensions etc, but the sniffer should work even if the numbers are
wrong. This method removes the volumetric, atmospheric, temperature variation
issues altogether and Freon doesn’t support combustion. Just make sure
there’s positive pressure (tiny amount) in the tank when searching for
that micro amount of Freon.
If you have a leak, do the best you can to
determine what caused it. Is a lack of fuel sealer opening an area of exposure,
have a crack in the wing structure, what? The cause may be pointing to the
appropriate repair. I wouldn’t just take the wing skins off only to find
out something minor was the problem.
Jim
From: Lancair Mailing List
[mailto:lml@lancaironline.net] On Behalf Of vtailjeff@aol.com
Sent: Sunday, August 17, 2008 11:13 AM
To: lml@lancaironline.net
Subject: [LML] Re: leaking wing on IVP
Ralf,
Sounds like you are going to have to pinpoint where the leaks are. The
builder's manual recommends using very low pressure air (1-2 psi) to check for
leaks. You must be certain you have drained all the fuel out of the wings and
there is no residual fuel vapors. You may end up having to remove the wings to
do this properly. Depending on the leaks you might end up removing one of the
skins of the wing. Once the leak is found then you must paint over the leak are
on the inside of the fuel tank with Jeffco tank sealant (a two part epoxy). You
might consider calling Mark Mahnke in Redmond. He has repaired these kinds of
problems in the past.
Best Regards,
Jeff Edwards
-----Original Message-----
From: bronnenmeier@GROBSYSTEMS.COM
To: lml@lancaironline.net
Sent: Fri, 15 Aug 2008 3:25 pm
Subject: [LML] leaking wing on IVP
I need some help/advise. I purchased a used
IVP with 250 hrs. It did not look very nicely and I knew that it needed some
work. I had a pre purchase inspection/anual done at Lancair and they confirmed
that everything was in a working condition and that the airplane was safe to
fly. Based on this I made my purchase decision.
I took the airplane apart and I am rebuilding
it right now (I did not have the money for a new kit). After painting the wings
we got a paint bubble during the buffing in the sun. I dug into bubble and
found some of that brown rubber under the primer (the sealer that is used to
seal the inside of fuel tanks - unfortunately I decided to just grind of the
original paint and leave the primer on) I decided to grind of all the paint and
primer around my leading edge and found that brown rubber stuff on several
spots along the leading edge. After removing the rubber I found wet spots in
the carbon fiber. After looking at the wing closer I found blue stains on the
very outside of the leading edge (visible by looking into the wing after
removing the winglets). This probably should have been found by Lancair during
the annual/pre purchase inspection.
I think my whole leading edge is soaked with
fuel since I see stains where no fuel tank is. I would also consider this as a
safety concern. My friends from the FBO here think the design of a wing without
any inspection panels is hazardous anyway. So I won’t find much help
there. One professional Lancair builder recommended to paint the outside of the
wing with sealer paint 8 0 I don’t feel very comfortable with his advice.
Can anyone give me advise on how to fix this
right. I would also feel more comfortable if I would have professional help on
this – any advise on this? Do you think I would have any success asking
Lancair for help on this since I purchased the plane based on their evaluation.
It's time to go back to school!
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