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Old 03-22-2014, 09:49 PM
xblueh2o xblueh2o is offline
Join Date: Apr 2011
Location: SF East Bay
Posts: 869
Default 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.
RV-8 with the Showplanes Fastback conversion
Emp completed except for glass work
Wings completed except for bottom skin and glass work
Fuselage underway
N18451 reserved
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Old 03-22-2014, 10:00 PM
jaradtke's Avatar
jaradtke jaradtke is offline
Join Date: Nov 2009
Location: Lutz FL
Posts: 167

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.
Jeff Radtke
Lutz, FL
RV-7A - New Build
Tail Feathers - Complete
ER Wings - Complete
Fuselage - Complete
Finish - Started
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Old 03-23-2014, 12:16 AM
Sugar Dunkerton Sugar Dunkerton is offline
Join Date: Apr 2012
Location: Long Beach, California
Posts: 30

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.
Mike F.
Long Beach, CA
Paid up
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Old 03-23-2014, 01:09 AM
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longranger longranger is offline
Join Date: Mar 2007
Location: 45G, Brighton, MI
Posts: 1,928

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.

Miles (VAF# 1238, Paid up as of 12/20)
RV-7 TU 904KM (reserved)
Wings Fitted and Finish Kit on site

Construction Log

1955 Cessna 170B flying since 1982

'To get something you never had, you have to do something you never did.' -Unk.
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Old 03-23-2014, 08:15 AM
wirejock's Avatar
wirejock wirejock is offline
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 5,120
Default 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.
Larry Larson
Estes Park, CO
wirejock at yahoo dot com
Donated 12/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (3,000+ hours)
Empennage, wings, fuse, finishing kit done. Working FWF
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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Old 03-30-2014, 11:44 PM
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mvidalr mvidalr is offline
Join Date: Aug 2011
Location: Monterrey, Mexico
Posts: 121
Default 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
Miguel Vidal
EAA #1133587
RV-8 SB Wings in Monterrey, Mexico
N511MV Registered
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