fuel tank slosh

I purchased a RV-4 and have flown it for a year. My mechanic doing the annual says that the Service Bulletin 11-9-13 was not complied with, sloshing sealant was used and it is flaking. What are my options?

wglenn1223 said:

I purchased a RV-4 and have flown it for a year. My mechanic doing the annual says that the Service Bulletin 11-9-13 was not complied with, sloshing sealant was used and it is flaking. What are my options?

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Bill, this topic has been discussed extensively the past few years. Try the Search engine using the term 'slosh' to find a lot of info. Here are some of the threads I found using that search:

http://www.vansairforce.com/community/showthread.php?t=108148&highlight=slosh

http://www.vansairforce.com/community/showthread.php?t=102162&highlight=slosh

http://www.vansairforce.com/community/showthread.php?t=104940&highlight=slosh

http://www.vansairforce.com/community/showthread.php?t=106097&highlight=slosh

Rest assured the slosh problem can be resolved but it isn't an easy fix.

P.S. Welcome to VAF, the ultimate RV info source!

Welcome to VAF!

Bill, welcome to VAF

Sam has done a good job of steering you in the right direction.

Slosh removal

I'm in the same boat as Bill on this one and I can say I have read all the posts relating to this problem. I've been saving the best for last on my rebuild. It seems the preferred method is to cut access panels between the ribs to get the slosh out. Well, I also have about 6 weeping rivets to deal with. So instead of cutting the holes I'm thinking of just removing the entire rear bulkhead. I haven't removed the tanks from the wings yet, so I'm not sure if this will be a wise decision.

Removing the rear panel from the tanks isn't that difficult. I know the inspection cover idea is popular but it is a difficult task to get the slosh removed and I can't imagine trying to work through those round holes and re-applying proseal where needed. Contact me if you would be interested on how I removed the rear panel.

The biggest advantage to cutting holes in the baffle is that you don't disturb the paint around the baffle rivets. And sealing the holes is much easier than sealing the entire baffle.
It's not that difficult to get the slosh out working through 4" or 5" holes.

"It's not that difficult to get the slosh out working through 4" or 5" holes."

How about some details of your process, Mel? You have suggested this before with no details... What kind of gloves won't get eaten by the MEK? What about breathing equip.. What is appropriate? How do you see inside and behind the stiffeners and back wall? What sort of rags or scrubbing products? How do you keep the MEK from damaging the paint on the outside? One little splatter and you ruin the paint... How long does your process take? I started on mine and determined right away that I didn't want to expose myself to those fumes for very long even with protection. How much MEK did you use?

How do you re-proseal rivets and corners that you can't see and do a good job getting it on the rivets and edges? How about some details?

I can see doing the inspection covers for a non-sloshed tank leak repair but removing slosh, at least the stuff that was in my tanks, it would have been a nightmare...

Steve,

My wife's kitchen gloves have performed the best with MEK. The package says "Nitrile" and chemical resistant. They are thicker than my disposable nitrile gloves that don't work so well with MEK.

Bevan

MEK

Make sure you use precautions when using MEK. Breathing those fumes can poison your liver in short order.


Chris M

Weep NO More

Another option is to call Paul at Weep No More in Minnesota. Ken at Vans told me about him. He used to exclusively seal leaking Mooney tanks, now he also works on RV Tanks. He will remove the aft baffle from your RV Tanks, clean the inside - completely, all slosh, pro-seal, everything except aluminum. He then re-seals the tanks with pro-seal (or similar) and re-installs the aft baffle with sealant and leak checks them.

Yes, the rivets holding in the aft baffles will need to be painted if you want them to match the tank, this is not necessary if you just cut holes in the aft baffles.

Yes, this costs money instead of time, but it is an option for those who prefer to avoid the sticky job.

Paul did my tanks and sent e-mail pictures of the process. The tank interiors were spotless after he cleaned them. He has the equipment and skills to do the job. He doesn't even want you to pay him until you have the tanks back in your plane and are happy.

Today I pulled my tanks in order to get the slosh out and fix a few leaking rivets. I opted to pull the rear baffle instead of the access holes. Come to find out, the rear baffle was closed up completely using blind rivets. Before I order a bunch of blind rivets (countersunk) is there a special rivet I need, or will any aluminum blind rivet do the job? I found some on ebay with a 1/4" grip. Also how do you seal a blind rivet? each tank baffle has over a 100 and none showed signs of leaking.

acam37 said:

Today I pulled my tanks in order to get the slosh out and fix a few leaking rivets. I opted to pull the rear baffle instead of the access holes. Come to find out, the rear baffle was closed up completely using blind rivets. Before I order a bunch of blind rivets (countersunk) is there a special rivet I need, or will any aluminum blind rivet do the job? I found some on ebay with a 1/4" grip. Also how do you seal a blind rivet? each tank baffle has over a 100 and none showed signs of leaking.

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The rear baffle is attached with sealed rivets, AD-41H, found on this page of Vans' catalog:

http://www.vansaircraft.com/cgi-bin/store.cgi?ident=1404098014-194-66&browse=hardware&product=poprvt

Or Aircraft Spruce:

http://www.aircraftspruce.com/catalog/cspages/blindpopriv.php



But removing a good rear baffle is a very drastic move....I would much prefer adding access ports as previously recommended.

Sam, thanks for the quick reply. FYI, I'm not the original builder so I've never built a tank. If you saw what I saw inside these tanks you would probably scrap them and build new ones. But I'm going to torture myself and try to save them. I think I can get all the mess out with a little elbow grease and get them sealed back up. So hopefully I have the correct rivets on the way from Vans. I ordered the AK (flush rivets) for the skins and the AD (round rivets) for the rear baffle. Will a quart of tank sealant do the job?