Loose wing tanks

[Jerrytex]

Anyone have any issues with the wing tanks turning loose? On my 4, it appears that both wing tanks are moving around a bit causing pinches in the fabric. I can flex the wings when they are folded and see movement between the spar and the tank. Maybe the silicone has let go? Any ideas on how to remedy this without recovering? If recovering is only option, has anyone repaired by only removing the fabric on one side of the wing? Is this an airworthy issue.

[cap01]

Jerry in Texas , I didn't have loose tanks but I removed the small tanks and replaced them with the big tanks . I removed only the top fabric , I had to remove the fabric a couple of bays farther out from the tank as to relocate the braces between the spars . If you do just remove the top be sure to leave enough fabric at the front and back to wrap the remaining bottom fabric around the leading edge and trailing edge so it can be glued properly . Other than the fabric being difficult to shrink on top of the tanks it's pretty simple glue , tape , shrink and paint . There are some pictures in one of my albums. Had to use safety wire to cut the rtv , my old tanks were glued in pretty good . Be sure to get the correct rtv from Kitfox . I couldn't get it locally since it has a shelf life and no one stocks it in this area .
Good luck

[mcomeaux]

Have new to me Model 4 with 6 gallon tanks. Replaced the Merecedes Blue seal in caps and was wondering which way the vent tube should be pointing forward or aft of the wing. How much trouble to switch to 12 gallon tanks at some time?


Regards

Mike

[cap01]

Mike , vent tubes point forward .
Two six gallon tanks just isn't enough gas . Like I mentioned in a earlier post , there are pictures in my albums of when I installed the large tanks . It's not a small task to change tanks but a good winter project when the weather isn't good for flying and the plane can be out of service for a while . A rib has to be removed and the tube between the front and rear spar has to be relocated a bay outboard . The angles are different for the spar attach fittings for the tubes so they either have to be mfgd or bought from Kitfox

[t j]

Anyone have any issues with the wing tanks turning loose? On my 4, it appears that both wing tanks are moving around a bit causing pinches in the fabric. I can flex the wings when they are folded and see movement between the spar and the tank. Maybe the silicone has let go? Any ideas on how to remedy this without recovering? If recovering is only option, has anyone repaired by only removing the fabric on one side of the wing? Is this an airworthy issue.

Jerry, if the RTV was past its expire date when the tanks were installed it will never cure and that may be the case and you will need to reset them.

I would get a second opinion before tearing into your wings. The RTV used between the tanks and spars is very tenacious. Having removed a tank I can say there is no way the RTV will ever let loose unless it was too old when installed.

The fabric on the top of my wings will form a wrinkle between the tank and rib when when the temperature gets cold. When it warms up the wrinkle dissapears. I think it is due to the aluminum parts contracting and expanding a slight amount with the temperature change. I have heard other kitfox owners have seen the same on their wings.

[mcomeaux]

Thanks for the quick reply..........

[MotReklaw]

TJones is right:

http://www.teamkitfox.com/Forums/sea...earchid=244739

[Jerrytex]

"will form a wrinkle between the tank and rib when when the temperature gets cold. When it warms up the wrinkle dissapears".

That is exactly where mine shows the Pinch in the fabric. Seems like it's getting worse. I suspect the tank is moving around.

I wonder if there is a way to inject some silicone bewtween the tank and spar?

[Jerrytex]

I posted a video of the loose tanks. The left side is worse than the right side. It looks like the tank has moved outward maybe a 1/16th of an inch. Enough to where it pulled the #1 rib loose. you can see the hysol crack. Thinking about trying to inject some adhesive through the fabric between the tank and spar. Not really excited about pulling the fabric and rebedding the tank and then having to do it again when I get the $$$$ for the Ethanol proof tanks. Any thoughts, ideas, concerns? Not real keen on flying it in this condition even though I suspect it has been like this for awhile.

http://youtu.be/1iLOHhc-vbE

[Jerrytex]

Started work on fixing my loose wing tanks. I decided to reuse my tanks instead of replacing with the Ethanol resistant tanks. Way to many mixed reviews on using Ethanol laced gas. The left tank was totally loose with no silicone holding. The right tank was held in with maybe 3-4 inches total linear amount of silicone on the front and more on the rear. It is strange too because the silicone feels weird. It is not rubbery but almost "crystalized". It almost turns to powder when I squeeze it. Very easy to remove. Don't see any signs of corrosion, pitting or rub spots.

Now for some questions. It appears that the original builder used plenty of silicone. However, it just didn't touch the spars in most places. On one of the tanks it looks like the back side had good contact but the front not so much. Then what did touch just pulled off with no effort almost as if the silicone was bad. I checked the manual and it looks like he did as per the manual but I guess the tanks don't fit that snug between the spars. In fact one tank is narrower on on one end when compared to the other end causing an slightly eneven gap between the spars and the tanks. I guess that is a characteristic of fiberglass though. Has anyone any any similar experiences?

I bought the correct non-expired silicone and I was thinking about running a bead under both the front and back lips of the tank and setting the tank onto the spars and let it dry. Then flip the wing over and pump silicone directly between the tank and the spar from the bottom side. That way I don't have 2 feet of a sillicone bead that is not touching anything. Thoughts, suggestions?