RV-6A Very Slow Build, Western Australia

[Dan 57]

Nice grin Paul
The more so enduring the frustration… nice seeing you forging ahead.

[PaulvS]

Thanks Dan, et al for PMs. What started out as 1 day job for SB 06-2-23 has blown out to be a much bigger job. I need to remind myself that one day this will all be worth it.

I made some more progress cleaning out the softened Proseal, using a spray gun with solvent and a stiff brush, supporting the tank on its nose in a stand. I moved everything outside in the yard to reduce the fumes and fire hazard.

It's become more evident that much of the sealant in the faying surface joints between the stiffeners, ribs and skins has also softened and reverted to goo. I tentatively removed the pop rivets between the baffle and flanges on an internal rib and was able to push a feeler gauge through the soft Proseal. I think therefore that the tanks need to come apart completely (approx 4-500 rivets to drill out!) for total cleaning and then re-assembly. This is because I'm not confident about the long term performance of new sealant over the old sealant that is still in the seams, in case it contaminates the new sealant.

For the record, my work log shows that it took 5 months to build the tanks in 1995.

** Edit/update
Added picture after removing tank baffle. Definitely needed to come off for repair, the Proseal underneath is a soft mess. Next step is to de-rivet and disassemble the tank ribs and stiffeners.

[PaulvS]

Both tanks are finally cleaned out, following removal of the aft baffles.

I now believe it won't be necessary to completely disassemble all of the ribs and stiffeners, because I've been able to wash out all of the Proseal goo using several litres of solvent. The most effective solvents were gun wash and acrylic enamel reducer, both have a high percentage of toluene. Acetone was partially effective and several other solvents that I tried did not work at all. I took the job outside due to the fumes and risk of fire.

The still hardened Proseal on the outside of the tank that was not affected by the avgas vapor was very difficult to remove and the only thing that would take it off was paint stripper containing methylene chloride. It took 4 or 5 applications and lots of scraping with a wooden stick to remove the sealant.

I can't say this has been the most fun period on the project but at least the worst part of cleaning is done. Thankfully a couple of buddies have helped me to hang on to my sanity during some dark moments!

The sealant that I ordered has arrived and I've got the .040 aluminum sheet to make the access covers. I will certainly not be putting any fuel into the tanks for leak testing this time round!

[Zero4Zulu]

My tanks had slosh loose. I initially thought I could clean them myself. I removed the rear panel which wasn’t really difficult. After getting started and realizing how much chemical exposure I would have to endure, I started looking for options. I found a chemical stripping company locally. They dipped my tanks and they came out nice.

I re-applied Proseal around all the ribs and rivets and re-install the rear panels. So far a few years since then, no leaks. For others needing to do this, maybe you can locate a chemical stripping outfit near you. Of course you would have to repaint the tanks too.

[PaulvS]

The tanks are fully cleaned and ready for re-sealing and while waiting for the rest of the sealant to ship I worked on the wing lighting.

There will be one Flyleds Single Spotlight in the leading edge of each wing, powered by an integrated wig-wag toggle switch on the panel. I fabricated aluminum brackets to mount the lights in the wings and made the curved plexi lenses using the tank leading edge as a form.

The lights are compact and weigh about 100g each and the hole in the leading edge is 2.5" square, which is adequate for the narrow beam.

Another lighting option that I considered was eBay Baja style 4000 (claimed) lumen spotlights, however these are heavier and more difficult to mount and seem to produce not much more light than the Flyleds 1200 lumen lights. As an added bonus, Flyleds are made down under, so there was no international shipping!

This lighting solution is for day VFR, using the wig-wag function to enhance awareness.

[Dan 57]

Flyleds are made down under, so there was no international shipping

Plus Paul offers first class service with top quality products
I upgraded my old halogen light with a combo leading edge landing / taxi, and I'm very happy.

Good work on those tanks, nice to follow your progress