Removing an extended range fuel tank

[Mark Albery]

I have a leak from one of the connecting tubes between my extended range fuel.

There isn't enough room to remove and replace that tube without removing a tank. I don't think they can be slid sideways against the ribs sufficiently for access.

So that would mean removing the trammelling rods that go through the tanks.

Can this be done safely without removing the wing? I presume new inspection hatches will be needed to access the outboard ends of the trammelling rods and I presume that they can be re-tensioned to the same length of exposed thread at each end.

I guess this is a fairly rare task so would appreciate if anyone has any experience or alternative suggestions.

The maintenance manual has no mention of tank removal.

[jmorrical]

I've finished the Carbon Cub EX(1) and have an Airworthiness Certificate. I've taxied it twice for various things. The last taxi I fueled it to nearly full for first flights. Since doing that when I open up the cockpit I've noticed a faint smell of fuel. I spent some time looking for a leak and the last place I looked was the tanks. When I took off the right side extended range tank cover I found a seep at a weld on the inboard tank.

Kit support offered a replacement tank, but that's a six month production delay. Another solution was to use ProSeal to patch over the seep. That was the course I initially decided on then CubCrafters Kit Support offered to repair the tanks with a quick turn around. They would leak check again also of course. So with great disappointment that is the course I've decided on.

I've seen the Service Instruction SI0020 Rev. C that has useful information. Does anyone have experience with extended fuel tank removal that would add something here? I am also trying to decide how I should box up the tanks with adequate protection for shipment. Any experience or ideas how I should make or find a box large and strong enough for the job?

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After clean up and less than one hour this is what I see.

[jmorrical]

As promised I have an update on the tank leak patch.

• I cleaned the area of concern with acetone.
• Scuffed with maroon Scotch Brit pad.
• Carefully (read carefully) set the shop vac hose into the tank fill to give a little vacuum that might help Loctite 290 wick into what I have come to call pin hole porosities in the weld.
• Slowly made several applications of Loctite 290 (Green) allowing it to cure for 24 hours.
• Applied JB Weld - Original Cold Weld over the area.
• Allowed 24 hours to cure.
• Filled tank and I'll check for what I hope is no leak tomorrow.

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This is my patch that did stop the leak. This photo is upside down. Can't edit my iPhone photos correctly for some reason.

[aeroaddict]

Sounds like a solid plan. Thanks for the update.

[Andy]

Well that's ugly and I'm sure a huge disappointment when so close to first flight. I hope you caught it and got the tank drained before the fuel damaged the wing paint.

If it happened to me I think I'd accept the CubCrafters offer of a new tank and remove the leaking tank for interim repair by a local welder.

Thanks for the link to the related SI.

[aeroaddict]

Sorry to hear of this!

For the leaking tank weld, as much as this should NOT have happened (a QC escape!), I think I'd go with the ProSeal fix. And yea, I'd request a new tank from CC.

I have no idea on how the remove a tank. But CC should.

[aeroaddict]

Any updates?

Any process on how to remove a fuel tank?

Thanks

[jmorrical]

Expedient repair strategy is holding well. Dry with no leak. Completed 10 hours of flying in Phase I. Just finished the first oil change. Fly on!

[aeroaddict]

Great news! Add the repair to your Condition Inspection Check List, and obviously keep an eye on the repair.

Enjoy the ride and fly on!

[Andy]

Previously referenced SI0020 is written for the CC11 but I would think the removal of the FX/EX drag wires would be similar.

Once the drag wires are out of the way wouldn't removal be a relatively easy drain, disconnect, and lift out? I say "relatively easy" because removal of the drag wires looks like no fun at all with the wing covered and installed.