Fuel leak leading edge 4P Wing


I have a Lancair IVPT that has developed a small pin hole leak in the leading edge of the wing.  Is there some way to repair this leak from the outside without sloshing sealer or opening up the area in the wing that is leaking?  Is it possible to spray something on the outside that might stop the very small leak.  The leak will show about 3-4 inches of dampness on the lower part of the wing in about 3-4 hours to provide some context for the extent of the leak.

Thanks much for any advice you might have to address this leak.

Denis Conkey, dconkey [at] conksite.com

Legacyl2k's picture

Every leak is different.  If

Every leak is different.  If it is a superficial leak in carbon or fiberglass.  I normally drain the tank.  Pull a very LOW vacuum (.9 or less) draw some  Acetone to clean then draw some thinned structure epoxy resin.  Let cure, done.  If metal same only substitute MEK for acetone and PRC tank sealer for resin.

bknotts's picture

You should be careful with

You should be careful with the management of the vacuum.  Some have used a shop vac or a vacuum cleaner to draw down a vacuum.  This can be a problem since a drained gas tank now only contains air and vaporized fuel.  The electric motor in many of these vacuum devices is not well shielded.  The result is an ignition source that can create an exciting time as the wing and shop vac become gasoline bombs.  Although I have no personal experience, it has happened.  Just a suggestion....

Legacyl2k's picture

Bknotts is right on, electric

Bknotts is right on, electric vac bad!  Plug the vent (I use a rubber stopper or clay).  Then use a hand vac pump w/gauge (amazon $20), make tank adapter.

With no static discharge

With no static discharge wicks on this IV-P original build, I’ve noticed increasing leading edge, loss of paint from static discharge. I can hear it on the headset when it discharges. I wonder if this could drill a pinhole or even generate a spark at the pinhole and fuel source. Somewhere I read the flashpoint of avgas is higher than such a discharge, but given this report, it’s worth rechecking?


Thanks for the responses. 

Thanks for the responses.  This is a turbine airplane therefore Jet A is the fuel so I'm not as worried about the spontaneous combustion, but I would not use a vacuum cleaner.  However, the static discharge is a possibility of why this happened as the primer is very thin where it is leaking.  This airplane is not painted and has over 500 hours so it might be more prone to have this happen.  Does the repair technique change for Jet A?  This wing holds about 50 gallons of fuel so I'm assuming when pulling a vacuum, I apply epoxy where the leak appears on the outside.  Is that correct?  I have tried to put tank sealer in this area without a vacuum applied and it worked for a few months but then the leak appeared again.  Very small but very annoying.  Thanks