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Old 05-12-2018, 05:38 PM
StressedOut StressedOut is offline
Join Date: Jun 2017
Location: Fullerton, CA
Posts: 130

I think the thing that most new builders fear on the tanks is working with the sealant and the possibility of a leaking tank when the work is finished. I counted myself in that group until a few weeks ago. We had one of our AOG teams (aircraft on ground) spend a couple of weeks with us dumb engineers to show us the reality of aircraft repairs on large aircraft. We did a variety of typical repairs under their supervision on a 737 we had in our boneyard and I picked up a bunch of useful information for my RV build.

They showed me how they dealt with sealant. Now I've read dozens of builder logs and many of the post on this site and nowhere was ever mentioned the tools and methods used by the professionals. I think we can adopt some, if not all, of these methods and tools to building the tanks for our RV's.

First, get a pneumatic sealant gun. If you buy a new one, it'll run you several hundred dollars. That's too expensive, but if you go to Brown Tool you can pick up a used Semco gun for $60. Once you get this tool the possibilities open up. You can use a bunch of different attachments that will make the job of sealing easier, with less mess and higher quality. You might even find it enjoyable.

Instead of using popsicle sticks to butter up a rib flange, use a roller. I used a roller to apply sealant to my rudder trailing edge wedge. The advantage to a roller is the sealant goes only where you want to and it doesn't get into the holes. It's far superior to a popsicle stick. You can get a continuous flow roller attachment ($47) for the Semco gun and replacement rollers at SkyGeek. I'd get the 2 in. roller attachment only because for some strange reason the replacement rollers are cheap (less than $3 each) and the 1 in. rollers are expensive ($17 each).

For fillet sealing there are a wide variety of dispensing nozzles you can choose from for the specific task required. If you're fillet sealing on the non-flange side you can use a standard round opening nozzle. If you're fillet sealing over a flange there's a specialty nozzle for that. Nozzles are inexpensive. They range from $1.50 each for standard nozzles to about $6 each for specialty nozzles. They are reusable if you solvent clean them after use.

Finally, sealing each and every rivet tail is another messy job usually done with a popsicle stick. There are premolded cap seals that you fill with sealant and press and twist into place. Very clean and high quality. It looks like my RV-14A tanks need about 1500 cap seals. I'm still trying to get a quote from PPG on the price of such a small quantity, so I'm not sure if this one will be economically feasible. If I can get them for 10 cents each or less then I'd do it. Any more than that and it gets too expensive for me. I'll let you know about the price when I get the quote. The seal cap video below shows cap sealing of HiLoks, but they make caps for rivet tails too. The concept is the same.

Roller sealing video: PPG Aerospace - Semco Ribbon & Roller Nozzles
Fillet nozzle video: PPG Aerospace - Semco Fillet Nozzles
Seal cap video: PPG Seal Caps

When I get my wing kit I'm going to build the fuel tanks first. I'm now really looking forward to it.
Art Jackson
RV-14A Kit#140433, N393AJ Reserved
Completed: Vertical Stab/Horizontal Stab
Scrapped: Rudder
Working on: Empennage (Elevator)
Construction log -
Dues paid on 10 October 2018
Member of EAA Chapter 92 (KCNO)
Pet peeve: "Lose" (rhymes with "booze") is the opposite of "find". "Loose" (rhymes with "juice") means "not tight".

Last edited by StressedOut : 05-12-2018 at 06:13 PM.
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Old 05-12-2018, 06:54 PM
jedimike007 jedimike007 is offline
Join Date: Jan 2005
Posts: 29

I've done 6/7/8/12 tanks, over a dozen-not one leak. It's one of those areas where being all setup with the correct tools and knowledge makes the job fairly easy. I understand the fear of leaks, but if your meticulous it will go fine.
I'm in East Tennessee for the summer and will happily build anyone a tank or assist if needed.

Mike S
Glasair III
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Old 05-12-2018, 08:07 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 3,959

Even easier than the seal caps, mix up some of the Type A sealant (I bought mine from and put it into a plastic syringe. Dot the rivet heads with that. Takes seconds, it's easy and your hands stay clean (except for the mixing part, maybe).

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Old 05-12-2018, 08:26 PM
diamond diamond is offline
Join Date: Sep 2009
Location: Rochester, MN
Posts: 709

By far the funnest part of the build for me. Just get a Semco gun and you will be fine.
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Old 05-12-2018, 10:36 PM
asw20c asw20c is offline
Join Date: Jun 2010
Location: Edgewood, NM
Posts: 164

I'm probably about 1 or two shop-sessions out from finally being done with the gorilla snot and building my tanks. Frankly, for me this has been hands down the worst part of the build to date. I'm now 3 months into building the tanks but still have the fuel senders and rear baffle left to install. For me, working with sealant has been miserable. It transfers to everything (despite shucking and changing gloves frequently) and for every hour of riveting it has taken about 1.5 hours of cleanup just to get it off of parts where you don't want it, your clecos, and your tools. If I were to build another Van's model I would seriously consider buying the quick-build wings just so I wouldn't have to deal with the tanks again. Imagine hot mozzarella cheese and superglue having a love child and you are getting close to what this stuff is like.
Having said all that, I admit that after I got my technique down it has gone faster with less stress, but that doesn't mean it has been fun. I was dreading the fuel tanks, and their reputation as being difficult and miserable is well deserved in my opinion. Now the only thing I'm dreading is the canopy.
I'm 18 months into my build and I'm still amazed at how much labor is required, but I view it mostly as a zen-like experience. It gives me something to do with my time, and I find it highly satisfying to see my project (slooooooowwwwly) coming together. I haven't felt that way about the tanks; only relief that I'm almost done with them.
Empennage Complete Except for Tips
Wings Underway
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Old 05-13-2018, 07:07 AM
didja didja is offline
Join Date: Jan 2017
Location: Portland, OR
Posts: 63

Originally Posted by asw20c View Post
Imagine hot mozzarella cheese and superglue having a love child and you are getting close to what this stuff is like.
Hahahaha!!! That's exactly what I remember from the foam rib experience! I am still on the fence. After hearing some of the responses here, I am actually leaning back towards doing my own. When I took this project on, I had told myself I would build the entire project myself...... I think I might just have to hold true to that!

I appreciate all the responses.
Scott Emerson
RV-14a Kit# 140432
Working on: Wings
Construction log:
Donation Paid (military)
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Old 05-13-2018, 07:10 AM
Kyle Boatright Kyle Boatright is offline
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 3,831

I didn't think sealing the tanks was that bad. One build session (probably 4 hours) for each tank with a helper. Yeah, you get messy, but it isn't that big of a deal.
Kyle Boatright
Atlanta, GA
2001 RV-6 N46KB
2019(?) RV-10
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Old 05-13-2018, 07:12 AM
kbalch's Avatar
kbalch kbalch is offline
Join Date: Jan 2005
Location: Clermont, FL
Posts: 407

Many years ago, I also dreaded doing the tanks on my -8 and wound up subcontracting them to Evan. With my -14 tail kit on its way and the wing kit due in July, I've been reading everything available on tank construction and I'm actually looking forward to it.

I'll be ordering a Semco gun and plan to utilize the fay sealing method. I may be back here eating crow on the subject in a couple of months, but I'm really not worried about it at all.

RV-8 N118KB (#81125) - Sold
RV-14A N114KB (#140494)
Standard kit begun 5/18 - FWF in progress
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Old 05-13-2018, 08:38 AM
TS Flightlines TS Flightlines is online now
Join Date: Apr 2010
Location: Ridgeland, SC
Posts: 2,333
Default The problem -

as I see it isnt in having an outside source building the tanks, its SHIPPING them to the owner UNDAMAGED. You guys in the shipping business know what I'm talking about. Would be a great side business for some of you airframe guys, but the wooden crate shipping costs might equal the cost of the tank.

Oh and the forklift holes in the crate--that would be a bummer.

Tom Swearengen, TS Flightlines LLC, AS Flightlines
Joint Venture with Aircraft Specialty
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7 Tail Kit Completed, Fuse started-Pay as I go Plan
Ridgeland, SC,
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Old 05-13-2018, 08:43 AM
asw20c asw20c is offline
Join Date: Jun 2010
Location: Edgewood, NM
Posts: 164

Originally Posted by Kyle Boatright View Post
I didn't think sealing the tanks was that bad. One build session (probably 4 hours) for each tank with a helper. Yeah, you get messy, but it isn't that big of a deal.
Are you kidding me? 4 hours per tank? Are we building the same thing? I have about a hundred hours in my tanks at this point. We must be building in very different ways.
Empennage Complete Except for Tips
Wings Underway
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