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Old 05-28-2020, 07:14 AM
Jim Kranich Jim Kranich is offline
Join Date: Feb 2019
Location: Colorado Springs
Posts: 4
Default Fuel Tank Rivets Seeping Fuel

I've been flying my RV-7A for a year now and have just noticed about 10 rivets in the fuel tank are seeping fuel, causing a bubble in the paint around the rivet head. Most of the problem rivets are on the top side of the tank and a few on the bottom. Has anyone experienced this and if so, what's the best fix?

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Old 05-28-2020, 07:43 AM
upperdeck upperdeck is offline
Join Date: Dec 2009
Location: Menomonee Falls, WI
Posts: 167

I had a row of 10 rivets seeping fuel on the bottom of one tank and a couple on the top of the other. Both were along the baffle at the rear of the tank. I bit the bullet, pulled the tanks, opened them up and applied sealant to the inside of the tank. Vans sells a kit to accomplish this. Leak test on the bench before reinstallation.
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Old 05-28-2020, 08:43 AM
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airguy airguy is offline
Join Date: Oct 2006
Location: Garden City, Tx
Posts: 5,592

If you do a deep-dive search on the forums here you'll find a lot of old posts on this subject. There is no firm concensus on what causes it, but there does seem to be a trend pointing to builders who used MEK to clean up the proseal on the exterior rivet lines before the proseal had firmly set, and some of those rivets subsequently leaking fuel. Nothing definitive, but enough anecdotal evidence to suspect there is a grain of truth in that route.
Greg Niehues - SEL, IFR, Repairman Cert.
Garden City, TX VAF 2021 dues paid
N16GN flying 900 hrs and counting; IO360, SDS, WWRV200, Dynon HDX, IFD440, G5
Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
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Old 05-28-2020, 08:47 AM
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9GT 9GT is offline
Join Date: Jan 2010
Location: Southern Michigan
Posts: 2,189

Are the wings quick build?
David C.
Howell, MI
RV-10: #41686 Under Construction
RV-9A: #90949 Under Construction
RV-10: #40637 Completed/Sold 2016
Cozy MKIV:#656 Completed/Sold 2007
"Donor Exempt" but donated through Dec. 2021
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Old 05-28-2020, 08:53 AM
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MiserBird MiserBird is offline
Join Date: Mar 2018
Location: Cornelia, GA
Posts: 71
Default Running mogas?

I had this happen many years ago on a '68 Cardinal when I started running mogas (long before ethanol was required) I've been reluctant to run mogas in my RV-3 for fear of the same.
Prick one of the bubbles and see if any fuel comes out. I never got a drop out on the Cardinal and could flatten the bubbles out so they were hardly noticeable. Nearly all of the bubbling rivets were on top of the wing.
Dave McKinnon
KAJR - Cornelia, GA

1975 Cardinal RG N1593H since Mar 1993
1980 RV-3 N3VR Bought flying Sept 2017

Dues current 2021

Last edited by MiserBird : 05-28-2020 at 09:22 AM.
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Old 05-28-2020, 10:26 AM
Jim Kranich Jim Kranich is offline
Join Date: Feb 2019
Location: Colorado Springs
Posts: 4

They are quick build wings. I leak checked them when they arrived and all was good.
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Old 05-28-2020, 10:29 AM
Jim Kranich Jim Kranich is offline
Join Date: Feb 2019
Location: Colorado Springs
Posts: 4

Thanks for the info. I might have to pull the tanks. I'm trying to find a method that doesn't require that. Do you know if anyone has had success with just applying tank seal on the exterior head of the rivet?
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Old 05-28-2020, 10:30 AM
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Raymo Raymo is offline
Join Date: Nov 2014
Location: Richmond Hill, GA (KLHW)
Posts: 2,340

My left tank leaked at the outboard end. I used some spare parts from the build to install an access panel (same as on the inboard end). Drill a hole large enough for an air nibbler to make the opening. As mentioned above, Vans sells a repair patch too, but it is less sturdy and is a one-time install using blind, sealed pop rivets. With the access panel, it is much easier to remove again if the seal isn't perfect the first time.
RV-7A - Slider - N495KL - First flt 27 Jan 17
O-360-A4M w/ AFP FM-150 FI, Dual PMags, Vetterman Trombone Exh, SkyTech starter, BandC Alt (PP failed after 226 hrs)
Catto 3 blade NLE, FlightLines Interior, James cowl, plenum & intake, Anti-Splat -14 seat mod and nose gear support
All lines by TSFlightLines (aka Hoser)
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Old 05-28-2020, 10:57 AM
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DanH DanH is offline
Join Date: Oct 2005
Location: 08A
Posts: 10,352

Can't speak for consensus, but the statistics are clear. Paint blisters over tank rivets has nothing to do with MEK application. Nor is it strictly a QB tank problem.

Jim, roughly speaking, when were your QB tanks assembled?

BTW, it is not difficult or risky to install access ports in the rear bulkhead.

Dan Horton
Barrett IO-390
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Old 05-28-2020, 02:25 PM
Ralph Inkster Ralph Inkster is offline
Join Date: Feb 2008
Location: Calgary, Alberta
Posts: 1,585

Interesting joggle around the edges of those cover plates Dan. Advantages of doing this?
built a few RVs, rebuilt a few more, hot rodded more, & maintained/updated a big bunch more
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