Primered Fuel Tank Ribs?

[WenEng]

I am just about finished with both wings and when I was assembling the fuel tank I noticed the ribs were not shiny aluminum but had a very slight green tint (almost clear). I know from other postings to be sure the ribs are clean clean clean before getting to the proseal phase. I spent considerable time with acetone removing the coating on the tank ribs and the ribs now look nice and clean. The question is, is it normal to have coated tank ribs or did I just remove something that shouldn't have been removed? These ribs haven't been touched in 10 years and perhaps back then Vans put some kind of near-clear primer on everything.

 

[D-Dubya]

Clean is Good

I haven't heard of anything being on the tank ribs. Generally speaking, you don't want anything inside the tank except for aluminum and Pro Seal. And fuel. There's a risk of the fuel reacting with whatever stuff is inside the tank, causing it to slough off and possibly plug the fuel line inlet/strainer. Which could lead to a major pucker factor issue in flight--at the least.

Not sure what that was that you cleaned off, but that shouldn't have caused any harm.

 

[airguy]

Several builders, myself included, have alodined the fuel tank internal surfaces for enhanced corrosion protection against the possibility (or certainty, in some cases) of running mogas with ethanol. Maybe needed, maybe not - but alodining won't cause problems with the fuel supply.

 

[az_gila]

...and it actually...

Several builders, myself included, have alodined the fuel tank internal surfaces for enhanced corrosion protection against the possibility (or certainty, in some cases) of running mogas with ethanol. Maybe needed, maybe not - but alodining won't cause problems with the fuel supply.

...increases the adhesion strength of the ProSeal a little....