Cracked fuel tank repair

[6643]

No vent holes?

Maybe it's just for pressure testing?

[8475]

No vent holes?

Maybe it's just for pressure testing?

That's right. I ordered the non-vented cap to do the pressure testing.

[8475]

I am in the middle of replacing my right tank. I replaced the left one a few years ago. Both leaked in exactly the same place as shown in your photos. I thought it was suspicious my leaks were in the same place. With your experience, I now believe its a manufacturing flaw. Mine were in metalized wings, by the way. Wonder if that makes a difference.

I've seen pics of a couple of used tanks on-line. The end-caps on those ribs had also cracked free of the rib in exactly the same manner as on my tank. Your experience with the metalized wings devalues my theory about the fabric playing a role. This fabric detail is immaterial though. I think its clear from these anecdotes that these tanks are prone to cracking in this area, with or without fabric. I believe this is a design issue, not a manufacturing flaw. This end cap induces a stiffness discontinuity that acts to focus vibrations at the leading spot weld on a material with a finite fatigue life.