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Fuel Tank T-905 Attach Bracket (9A)

skelrad

Well Known Member
Friend
The fuel tank attach bracket is made of 6061 angle. I have finished my tanks without leaks and moved on. As I was starting another section in the plans, I just happened to glance at a section of the fuel tank instructions, and now I'm wondering if I have to jump back to redoing something on the tanks. I did not prime the T-905 attach angle before I riveted it onto the inboard rib because I figured I'd hit it with primer when I paint the entire tank down the road. When I was building the tanks I was in the "don't prime anything" mindset, and I just didn't think about the fact that the mating surface between the attach bracket and the rib should get primer.

So the question is, do I just prime the rest of the bracket down the road when I shoot paint, or, is this critical and I need to rip things apart to drill out the attach bracket to prime that mating surface? I can't remember if I put proseal on that surface or not (I think I did on one, but not the second tank, because I realized that as long as I sealed the inside of the tank, the bracket didn't need it). I'm really dreading the thought of pulling off the access panel and drilling out the bracket just to cover a few square inches with primer, but now is the time if it truly needs to be done!
 
If it was me...

If it was me, I would not take it apart to prime.

The rib that it is attached to is most likely Alcad sheet, so you have one layer there in contact with the 6061. As long as the exposed part of the 6061 bracket is primed, and the seam between the 6061 bracket and the rib eventually has a paint or primer fillet, I personally wont not worry about it.

Since the Alcad and other primed areas of the part are in contact with the 6061 bracket to rib interface, it should provide corrosion protection. Besides all this resides under a fairing anyway, out of the elements.

The potential to screwing up the rivets holes during re work is too much risk in my opinion. JMHO. YMMV
 
Yeah, I'm leaning towards just leaving it alone unless I hear any compelling reasons not to. Everything I read says 6061 actually has great corrosion resistance, so even though it doesn't have an alclad layer and Van's rightly says to prime it, I'm guessing in a protected environment it'll be a non-issue even though it's up against a rib. I suppose I could also encapsulate the mating surface edges with proseal so water doesn't get into the joint (assuming it's dry after my leak test soaking).
 
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