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  #1  
Old 05-04-2021, 05:47 PM
Wing nut Wing nut is offline
 
Join Date: May 2017
Location: Glyndon, MN
Posts: 5
Default Primer inside a fuel tank!?

A friend bought older RV6 partially built kit. He recently completed one fuel tank and went to start the other and noticed the parts were all primed except the skins. Of course heís wondering why the heck he didnít notice it before building the first tank. It looks like it is the Sherwin Williams wash primer. His question to me was ďdo you think the primer in the tank is a problem?Ē Gosh I really donít know I said. Thatís a good question for this forum.
Heís ready to rip the first tank apart and re do it but would appreciate thoughts and input you may have. Thanks
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RV 8 flying since 2010
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  #2  
Old 05-04-2021, 07:42 PM
xkape xkape is offline
 
Join Date: Apr 2019
Location: East PA
Posts: 24
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Chances are it's fine, but there's no way to know for sure. I have worked on many certified aircraft with primer on the inside of the fuel tanks that did nothing, but who knows what kind of primer the previous builder used.

What you could do is fill the tank partially with fuel and leave it for a few weeks to see what happens. Drain the fuel and if the fuel looks clean and the primer hasn't softened up, I wouldn't worry about it.
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  #3  
Old 05-04-2021, 08:42 PM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
Posts: 871
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Is it possible that the ribs were Alodined? And itís not really primer at all?
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  #4  
Old 05-04-2021, 08:59 PM
JDeanda JDeanda is offline
 
Join Date: Apr 2013
Location: Ventura, CA
Posts: 261
Default Slosh?

Iíve seen a pair of tanks that had sloshing compound that looked like zinc chromate. It felt a bit soft under a thumbnail, not a all like chromate primer. Not that sloshing is a great idea, but at least itís not primer. Iíd go with xcapeís idea of putting fuel in and seeing what happens. BTW, there is an old Vans Service Bulletin about sloshing compound bubbling and separating from the insides of fuel tanks. (and thatís what was happening to the afore mentioned tanks) Even if itís doing that, all is not lost. Weep No More can still save the tank... for a price.
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  #5  
Old 05-04-2021, 09:14 PM
Wing nut Wing nut is offline
 
Join Date: May 2017
Location: Glyndon, MN
Posts: 5
Default

Quote:
Originally Posted by Taltruda View Post
Is it possible that the ribs were Alodined? And itís not really primer at all?
I asked him this exact question and he can remove the primer from the ribs on the other tank parts.
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  #6  
Old 05-04-2021, 09:51 PM
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PaulvS PaulvS is offline
 
Join Date: Aug 2019
Location: Western Australia
Posts: 713
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Vans sell a fuel tank repair kit which allows round access holes to be cut in the rear baffle so as to get inside the tank without major disassembly, then patched. This may be an option for cleaning off the primer in the completed tank, if that is what your friends decides to do.
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  #7  
Old 05-06-2021, 08:47 AM
Wing nut Wing nut is offline
 
Join Date: May 2017
Location: Glyndon, MN
Posts: 5
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Thanks guys. Iíll pass this on.
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  #8  
Old 05-06-2021, 07:27 PM
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gmcjetpilot gmcjetpilot is offline
 
Join Date: Jan 2005
Posts: 4,502
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If it is good epoxy primer it is OK. What is less desirable is the slosh compound that was recommended back in the day by Van's. It is a tank sealant, long been out of favor. It was white. Primer, if quality epoxy primer it will be fine with Av gas. Even if a little dissolves it it not going to cause an issue. If it was poorly done and flakes off then that might bock to filter. Monitor to fuel filters.

There is no PHOTO... so this is a qualified answer and you accept all risk. (Disclaimer required by my lawyer at Dewey Cheatem and Howe. Cheers)
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  #9  
Old 05-06-2021, 08:00 PM
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wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 4,661
Default P60G2

Probably no help but I have learned to keep Alumiprep far away from SW P60G2. Peels the stuff off like paint remover. Not sure why but I think it's some sort of chemical reaction.
Just an idea if it is SW Wash Primer P60G2.
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Donated 01/01/2021, plus a little extra.
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  #10  
Old 05-08-2021, 08:23 PM
Pilot8 Pilot8 is offline
 
Join Date: Sep 2018
Location: California
Posts: 107
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No way I'd fly with tanks like that! The aluminum is aggressively roughened for tooth adhesion, cleaned with acetone to remove oils that improves adhesion, then liberally lathered with proseal for sealing and adhesion. Primer is an unwanted and undesirable feature to add to the stackup- off label as they say. I usually answer questions about doing tough jobs by asking myself: "When the tanks start leaking in the future, what would I have been willing to do now?". Buy the proseal remover at Aircraft Spruce , drill out the rivets, clean everything up, and do the job right- you'll feel much better when it's done.
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