Need to replace aluminum wing tank

[dav8or 20]

Looks like I will probably have to replace my aluminum left wing tank. I went to the airport to fly this morning and it was bone dry. I always keep that one full so the gas must have leaked out onto the hangar floor. I will look at it closer tomorrow morning but I did see a wet spot on the fabric near the tank outlet connection.

Has anyone done this replacement with a speed wing? I am wondering if this is something I will have to custom fabricate a tank or is there something available. I have seen the plastic tanks at wingtanks.com but guessing that they are shaped for the STOL wings.

Thanks, Dan

[1avidflyer 1983]

Not really what you asked, but you might try sloshing it with a tank sealer.  Might work for a while.  Cost about $40 or so.  Have to take the wing off and roll it around a bunch with the sealer in it. 

[EDMO 1078]

Not really what you asked, but you might try sloshing it with a tank sealer.  Might work for a while.  Cost about $40 or so.  Have to take the wing off and roll it around a bunch with the sealer in it. 

Agree - If it was my aluminum tank I would buy  CASWELL sealer and try that before replacing it.   But, could it be a leaking fitting or line?  Can you check that first?   EDMO

Edited 28 Jan 2017 by EDMO

[lostman 198]

Personally I'd put money on the chance there is something besides the fuel tank leaking. As Ed said above, check everything before you get too far into this project of replacing. The likelihood of the tank itself starting to leak if it was sealed before isn't nearly as great a s fitting, hose or other item. 

Good luck, let us know what you find. 

[1avidflyer 1983]

The aluminum tanks in Kitfoxs and Avids did start to leak after a while.  3 of the 3 al. tanks in Avids I had started to leak after a while.  In the first Avid with one tank, it started to leak a while after I sold it.  In the other Avid with 2 tanks, they started to leak before I sold it, I sealed the tanks and they held for a while.  I believe they eventually started leaking again.  If it was me, and I was wanting to recover the wings anyway, I would of course change to fiberglass and be done with it.  If I was hoping to keep it going for a while and maybe eventually having to deal with it, then I would buy the seal kit and use it, while hoping it would last as long as possible.  JImChuk

[EDMO 1078]

The aluminum tanks in Kitfoxs and Avids did start to leak after a while.  3 of the 3 al. tanks in Avids I had started to leak after a while.  In the first Avid with one tank, it started to leak a while after I sold it.  In the other Avid with 2 tanks, they started to leak before I sold it, I sealed the tanks and they held for a while.  I believe they eventually started leaking again.  If it was me, and I was wanting to recover the wings anyway, I would of course change to fiberglass and be done with it.  If I was hoping to keep it going for a while and maybe eventually having to deal with it, then I would buy the seal kit and use it, while hoping it would last as long as possible.  JImChuk

I agree - But to get back to the original post - I think someone on here has used the STOL undercambered fiberglass tanks in the Speedwing - maybe it is in some old posts, or the builder will speak up?   You may have to glue some false ribs to the underside of the tank to match the Speedwing profile.   Kitfox 1-3 tanks may work, and they are now "alcohol resistant".   EDMO 

Edited 28 Jan 2017 by EDMO

[C5Engineer 1170]

My speed wing MK4 has the poly tanks in it.

[dav8or 20]

Thanks, going to look at it closer this morning. The fabric at the trailing edge in that bay is messed up and loose so at the very least I will probably have to recover/patch that section. According to the logs the original builder replaced the right tank with fiberglass not long after the plane was completed because it leaked. It would be nice if the poly versions came in the speedwing profile too.

Dan

[lostman 198]

I didn't realize that the aluminum tanks became a problem. In my experience outside of Avid/Kitfox aircraft they rarely leak or have issues. Good luck with whatever you end up doing. Hopefully the damage is minimal and the repair is easy. 

 

[dav8or 20]

I removed the finger strainer and re-sealed the threads when re-installing it. Poured a couple gallons in the tank and immediately got a fast drip from the flaperon after it ran down the inside of the fabric along the inboard rib. For now I am flying right tank only but now I seem to have a charging, battery, starter or possibly some combination of these problems. Once I get that sorted out I may try sloshing the tank for now until I figure out what I want to do for replacement.

Dan

[wypaul 448]

I didn't realize that the aluminum tanks became a problem. In my experience outside of Avid/Kitfox aircraft they rarely leak or have issues. Good luck with whatever you end up doing. Hopefully the damage is minimal and the repair is easy. 

 

The Taylorcraft F21 just to name one had leaky tanks due to poor mounting design of the tank.  If a tank was designed with a good mounting system for the Avid/Fox line the Al could work.  F21 came up with a solution thru design change.

[marksires 484]

When I'm looking at planes, if I see sloshed sealant in the tanks or in the logs, I am unlikely to purchase that plane.  It WILL, eventually, start peeling.  When it does, it will clog your fuel lines/filters, and you'll have an off airport landing.

If I did purchase a plane with sloshed tanks, I'd have priced  it with replacing the tanks subtracted, because I would do that immediately before the first flight.

Mark

 

[Avid90 12]

Has anyone looked into having a bladder tank made to fit into the aluminum fuel tank?

[Geoffrey Thorpe 31]

Not that hard to tig weld any cracks after properly prepping it.

But, in my ride (Merlin GT not Avid) I've had new cracks pop up in different spots on the seams. I suspect that the original welding did not have good penetration.

[dav8or 20]

When I'm looking at planes, if I see sloshed sealant in the tanks or in the logs, I am unlikely to purchase that plane.  It WILL, eventually, start peeling.  When it does, it will clog your fuel lines/filters, and you'll have an off airport landing.

If I did purchase a plane with sloshed tanks, I'd have priced  it with replacing the tanks subtracted, because I would do that immediately before the first flight.

Mark

 

In my case it would not lead to an off airport landing. I would notice a lack of fuel flow from that tank and switch to the other. I have 2.5 gallons in the header tank that would easily get me to the nearest airport.

I am not excited about sloshing myself but it would possibly give me back my reserve tank without having to do major surgery on the wing and trying to find or make a suitable replacement for the tank.

[dav8or 20]

Not that hard to tig weld any cracks after properly prepping it.

But, in my ride (Merlin GT not Avid) I've had new cracks pop up in different spots on the seams. I suspect that the original welding did not have good penetration.

I looked inside the tank along the one seam and the weld penetration is very inconsistent. I'm sure the tank could have been built better.