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-   -   A tale of two tanks (https://vansairforce.net/community/showthread.php?t=111100)

xblueh2o 03-22-2014 09:49 PM

A tale of two tanks
 
Posting in the general section to get the broadest distribution.
I have a set of QB 8 wings. I removed the fuel tank access covers today to have a little look see and I am wondering if this is normal.
Neither picture is great but you will get the idea if you look hard enough.
In one wing there is some considerable amount of tank sealant applied to the T-407 reinforcing ring and the associated platenuts.
If you look in the inspection mirror you can see that there is a complete covering of sealant from the open lip to beyond the edge of the T-407.



In the other wing the sealant is used far less liberally. The rivets for the platenuts are all covered and there is a bead of sealant extruded from under the T-407 but there was not a slathering of sealant applied like the other wing.



For those of you with experience building tanks, what is your opinion?
Since they are QB wings they have in theory already been leak tested and passed but I am curious what the collected wisdom thinks regarding the amount of sealant on the second tank.

jaradtke 03-22-2014 10:00 PM

It?s interesting that the rib fillets on the tank with less sealant on the T-407 look to be more substantial than the one with the sealant all over the T-407. I wouldn?t be too concerned with the lack of sealant on the backside of the T-407, if the access cover is installed properly the only ?weak link? is the cover screws.

Sugar Dunkerton 03-23-2014 12:16 AM

I'm pretty sure my slow build instructions are not to use any sealant on the ring or platenuts, because the flush shop heads on the exterior of the rib will be covered in sealant anyway.

longranger 03-23-2014 01:09 AM

I sealed the nutplate rivets, but it isn't really necessary. If you reinstall your cover plates like the photos below (sealant only, no cork gasket), they won't leak. I used Torx head screws to make them easier to remove if it ever becomes necessary.




wirejock 03-23-2014 08:15 AM

shop heads
 
Another observation.
There are no dollops of sealant over the shop heads on the stiffeners.

I sealed my ring as well but used floating sealed platenuts.

mvidalr 03-30-2014 11:44 PM

Leak-proofing
 
If they were both built by Van's, probably they found a leak around the ring during testing and decided to completely seal the perimeter, whereas the other tank came out leak-proof. My 2 cents


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