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De-Slosh RV-4 tanks; quotes vs reality

grantcarruthers

Well Known Member
So I have a leaking tank and I'm about to put it on the market in the next year. The borescope pictures of the tank look solid with no bubbling and zero adherence issues. The builder must have prepped very well but there are a couple hairline cracks that are stained blue and likely the cause of the leaks.

As there are no known and reliable ways to seal the cracks; and to get away from the 25 hour inspections it is unfortunately time to de slosh these tanks.

As far as doing it myself and having it signed off by an AnP, what are the realistic costs in ProSeal, Mek, and hours of labor? It looks like the tank repair kits from Vans will be under $200 easily. What tools and expenses will make this project successful?

Evan has too many negative reports to consider having 2 tanks built by him

WeapNoMore quotes $1500/tank and a 2-3 month wait to get started

Hotel Whiskey quotes $2000/tank, no mention of a backlog

I have the time to do it myself but how realistic is it? None of the processes seam too terribly difficult, just tedious. What are the chances to avoid repainting? Or is that a forgone conclusion after removing the screws and tanks from the wings and using chemicals capable of removing slosh?

Thanks very much for your time and opinions
 
I don’t see how one could ever get all the slosh out working through 5” holes in the rear wall. I tried one bay and sent them to Weeps. Very time consuming, breathed a lot of MEK and not pleasant work at all. The price quoted is about double what mine were a few years ago. Shipping is also very expensive. I would build new tanks before trying to remove the slosh myself.
 
I got the slosh out of a set of RV-4 tanks. I had to destroy the rear baffles to get access. It’s a tough job for sure. It would be easier to buy new tanks.
 
Just curious..... why would you need to get it signed of by an A&P? If you do the fix yourself, YOU make the logbook entry. You shouldn’t need an A&P for that, and you don’t have to be the builder. I’ve seen two back baffles removed from RV8 tanks in the last two months at my airport. It’s a little messy, but if you’re careful and have a couple sharp thin blade tools, it’s not that hard. Each tank was removed, disassembled, cleaned, and ready for resealing and reassembly in two days. That should be quicker than building new tanks, and you won’t have to figure out how to match drill the tank attach holes accurately on your RV4.
 
Having just sealed up a couple of leaky tanks, it isn't terribly difficult to use the tank repair kits from Van's. I can't comment on the difficulty of removing the slosh, since these didn't have that complication. I did however have to scrape out some plastic like epoxy sealant (Rhino fuel sealer by Jeffco) which was poured in and hardened along the back baffle. The normal pro-seal is easy to remove with Poly-Gone, but this stuff was not affected by it at all. If there is a recommended chemical to remove the slosh, then use that by all means!

I wrote up a blog article on the tank repair job here.

Photos of both repairs are here and here.

If you decide to build new tanks, then be sure to check out the video from Van's.
 
As far as doing it myself and having it signed off by an A&P,

Anyone can do any and all maintenance on an Experimental Amateur-Built aircraft. A&P sign off is only required for the condition inspection if you do not have the repairman certificate for that aircraft.
 
I've been looking at what it takes to do the job down the road if it starts to fall in any way. I'm not looking forward to it, but it doesn't look impossible either.

There are some tools I've looked at for removing sealant. There may be other sources too.
https://www.yardstore.com/sealant-cutter-5-piece-set-0-83
https://www.yardstore.com/handheld-phenolic-scraper-1-x-7-1-2
https://www.yardstore.com/phenolic-scraper-for-rivet-gun
https://www.yardstore.com/sealant-scraper-5-piece-set-used-9-x-3-4

Scrapers, cutters, etc., I'm planning to try pretty much everything and see what works best.
 
Tanks

I had slosh in my right tank that was failing. Rather than mess around with putting a bunch of holes in the baffle I just built a new tank. It requires some sheet metal skills knowing some techniques for picking up the holes but id rather do that than mess with mek.
Just my 2cents

Cm
 
I got the slosh out of a set of RV-4 tanks. I had to destroy the rear baffles to get access. It’s a tough job for sure. It would be easier to buy new tanks.

This is the man I would listen to. He has done/posted much of his rebuild experiences.
 
Replace them

I'm not the "man" But, I just last week finished a new set of tanks for my 2001 RV-6A I didn't build.
I have built tanks before.
It is a real good feeling after seeing the inside of the old tanks and the @%$% job done before. I am a believer in doing it right the first time.
I now never have to worry about the problems of the old this or that.
I did a much better job on these and less sealant to.
New tanks, senders, flip flop tube, shiny aluminum. Its the way to go.
Oh ya the possible buyer will have a rosy feeling also. Cause you'll show pictures of the new tanks insides.
Oh ya watch Scotts video and you'll get a much better grasp on the build. Maybe enlist somebody else to help for courage help.
Enjoy the build. Art
 
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The guy who bought my 4 decided to remove the slosh in the tanks. It took him 2 weeks using MEK and elbow grease to get them cleaned out, resealed and reinstalled. He removed the rear baffle so he had good access. He told me it was not a difficult job but was a messy PIA.
 
Slosh removal not hard to remove

I have removed slosh in both my tanks. Professional Strength GoofOff removes the slosh pretty easy. In 20-30 seconds or so it will wrinkle and you can wipe it off. You may have to apply it a second time to remove some of the areas. It will soften Proseal where you can use a plastic putty knife this is the part that will take the majority of your time. I soaked a rag and put it on the Proseal for a few minutes or so and scrape the Proseal away. It took me 30 hrs / tank between removing and re-installing the tank. FYI If you are having trouble with removing the screws on the tank use an impact screw gun with a good quality new bit. Without the impact gun on my first tank I stripped about 8 screws. With the impact gun on my second tank I stripped 2 or 3.

I cut rectangular holes in the rear baffles (I drilled 3/4" holes in the corners using a step bit). The rectangular holes are bigger than the round holes so it's easier for you to work. I had the baffle plates made and pre-drilled for $70/tank.

Use the 3oz Proseal tubes (Chemseal is about 40% cheaper than Proseal and is the same stuff). You have about 1.5 - 2 hrs of working time. Get the $14 mixer for the tube or make you own but it well worth it to mix using a drill than by hand 40 or 50 times. Don't go too fast with the drill so you don't heat up the sealant because it might give you less working time. It will take you about 4 tubes / tank including the baffle plates. You will not get a nice bead of sealant in the tank because you will not be able to apply it like tube of caulk. Use tight fixing rubber gloves and apply with finger. Don't use the middle finger or you will offend your tank :)

Time consuming Yes. Hard, not really
 
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