polishpilot

polishpilot

Well Known Member
I am working on my QB Wings, specifically testing the tanks. I have used the balloon method and the manometer method. So far I have found no rivet leaks. There was a slight air bubble at the edge of the tumbler on the locking gas cap (no worries). The manometer and balloon tests will hold for a three hours or more. (I would like better). I did find a leak coming from behind where the T905 support angle attaches to the front of the inboard rib.

I need advice! Should I try to proseal, after scuffing and cleaning all around the angle support? I definitely hate to completely dissassemble the tank if I do not have to.

See picture below.

P1030863.jpg
 
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zilik said:
Remove the access cover and proseal from the inside. Its easy to do now.
Click to expand...

This is the best suggestion.

I also recommend you replace the pan head screws with cap screws, when you seal it up.

With the wing on the plane, it is much easier to get in there with an allen wrench to remove those screws, if you ever have to.
 
I removed the sender plate this afternoon and looked inside. There is a lot of proseal behind the T905 backing brace on the inside. It almost looks like a second application of proseal may have been applied (not sure) over the first application; indicating the factory in the Philipines may have found a leak. :confused::confused:

Will new proseal attach to old proseal? And is there a method to remove "The Glob" from the inside corner of the tank.

I will try to get a decent picture in the morning and post it.

A phone call to Van's may be warranted, also.
 
Proseal Away

I wasn't proud when applying the proseal when building my fuel tanks. I loaded all the seams up as much as I could. I didn't care how "neat" it looked, I didn't want them to leak. You aren't going to see that area when it is finished. I attached a low pressure guage and put 1 lb of air in each tank and they both held the full 1 lb for 24 hrs each. Subsequently, 4 1/2 years later, zero leaks with full fuel. Check out these photos from my build...
http://www.drrv7.com/FuelTanks.html Proseal away! Happy Building!
 
Question

I guess my question is why did you test the tanks? I too have quick built wings. I assumed they were successfully tested. Well we all know what assumed is an acronym for. Working on the fuselage now (not a quick build). I'll test the tanks when it's time to connect the wings. If I'm not too old.
 
OK, here is a beautiful specimen. Whoever did the proseal work in this corner is an artist. :rolleyes: I might have him do the finish work on my 9-A. Anyway, I called Van's for additional input after removing the coverplate and viewing "the BLOB". Suggestion is; clean thoroughly around the the blob and add proseal. Then, apply a bead around the outside angle bracket. Interestingly, there is a little hole inside (see pic) that corresponds closely with the location of the leak on the outside.

Thanks for all the input fellas. Now back to work and hope it comes out OK. I will let you know.

P1030865.jpg
 
Several

Yes, I see several places where the seal might be compromised. It's as if it was put on so thick that it shrunk and cratered when it cured...

Nevertheless, should be an easy fix as Van's suggests.
 
longranger said:
I'm surprised to learn that the price of a QB wing doesn't include leak-free tanks...:confused:
Click to expand...

My apologies for that sarcstic comment.:eek: I assume that QB tanks do get tested, and repaired if necessary, but l guess a few leakers do get through ocassionally. As good as Van's is, I bet they'd make good on them, (especially if there were multiple leaks) though you might have to meet them half way with shipping. For a single, easy to repair leak, it wouldn't be worth the bother.
 
Well, here is the update.
I cleaned and scuffed up the old proseal inside the tank and added more over the top of the "glob". I resealed the access plate and used socket (allen) bolts to attach it. I also applied proseal around the edges of the T905 angle bracket. Friday, Dec 30th, I balloon tested the tank. This morning, Jan 1, the balloon is still inflated after 42 hours. I think I got it.

In addition, I found a leak on the OTHER tank coming through the threads under the lock nut on the fuel pick-up line in the access cover. I have removed the nut, scuffed up the washer and nut, applied proseal and replaced the nut. This should have forced the sealant in good. I will be testing that this coming week.

Thanks for all of your input.

Jim
 
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