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Wing Tanks - Pro-Seal

Scott Hersha

Well Known Member
Well, today I got my first taste of dealing with pro-seal (Flame Master actually) on my RV14 fuel tanks. My first 2 airplanes had QB wings, so I've never actually built fuel tanks and I've never used pro-seal until today....... What a mess! It took me almost 4 hours to attach 3 items to each of the the inboard wing ribs. There were supposed to be 4 things, but the large 3/16" rivets used to plug tooling holes proved to be more of a challenge than I could deal with while the sealer was ready to go. I got two rivets in one of the ribs, but practically destroyed it in the process. I whaled on the rivets with a large hammer using my C frame as called out in the plans, and it barely squashed it at all. I bought some 3/16" Al pulled rivets at a hardware store and will seal them in place tomorrow.

The problem I'm going to have with the wing ribs is getting them clecoed in place. It took me 3 hours to dry clecoe the ribs in place to see if they would fit. I wouldn't have been able to do it without a rubber mallet. I've read the posts from Rick Gallati and others about Fay-sealing the ribs in place and would like to do that. However, when I look at the process with online pictures, it looks like Rick clecoed the ribs to the upper skin and then just rolled the skin around to clecoe the lower skin to rib holes. That would be impossible with my kit. When I tried that, the bottom skin holes missed by almost a full hole. There was no way to make the bottom set of holes line up - I tried for 2 hours. The only way I could put this thing together was to use the cradle, installing the ribs from above and putting considerable pressure in the ribs to get it down into the leading edge. I had to use clecoes to sort of 'wedge' it down into position. Sort of reminded me of some medieval torture chamber. If any of you have a method of doing this that is a little less 'abusive', please let me know. My plan of wet clecoeing all ribs in place in one day is looking unlikely at this point. If I have to struggle so much to get the rib in position for clecoeing, I'm afraid I'll wipe off the pro seal in the process.... help please........
 
There were supposed to be 4 things, but the large 3/16" rivets used to plug tooling holes proved to be more of a challenge than I could deal with while the sealer was ready to go. I got two rivets in one of the ribs, but practically destroyed it in the process. I whaled on the rivets with a large hammer using my C frame as called out in the plans, and it barely squashed it at all. I bought some 3/16" Al pulled rivets at a hardware store and will seal them in place tomorrow.

The 3/16 " rivets are only meant to plug the holes, not hold the fuel tank on.
Barely squashing them is enough... just so they are tight enough to not come out (I thought the construction manual said that).

Also, in this case it is not necessary to install the rivets wet (I don't). Scuff the interior surface around the hole, install the rivet, and then smear a coating of sealant over it. Done.

Make sure the pulled rivets get coated with sealant real well. They are hollow in the middle where the stem is... potential leak.
 
The problem I'm going to have with the wing ribs is getting them clecoed in place. It took me 3 hours to dry clecoe the ribs in place to see if they would fit. I wouldn't have been able to do it without a rubber mallet. I've read the posts from Rick Gallati and others about Fay-sealing the ribs in place and would like to do that. However, when I look at the process with online pictures, it looks like Rick clecoed the ribs to the upper skin and then just rolled the skin around to clecoe the lower skin to rib holes. That would be impossible with my kit. When I tried that, the bottom skin holes missed by almost a full hole. There was no way to make the bottom set of holes line up - I tried for 2 hours. The only way I could put this thing together was to use the cradle, installing the ribs from above and putting considerable pressure in the ribs to get it down into the leading edge. I had to use clecoes to sort of 'wedge' it down into position. Sort of reminded me of some medieval torture chamber. If any of you have a method of doing this that is a little less 'abusive', please let me know. My plan of wet clecoeing all ribs in place in one day is looking unlikely at this point. If I have to struggle so much to get the rib in position for clecoeing, I'm afraid I'll wipe off the pro seal in the process.... help please........

Sounds about right. When I built my tanks I had everything clecoed together then would seal 2 ribs each session. Take out one rib at a time seal it up, clecoe it back in then do the 2nd rib. After both ribs are back in place start riveting them in. Make sure you give the sealant time to set up (a day or 2)then move on to the next set of ribs.
 
Scott, I'm just finishing my tanks all but for the closing up the tank baffle. I did not find installing the ribs with proseal more difficult than dry other than for not making a mess. I took the time before prosealing in the ribs, to tape up strips of masking tape on all sides of the ribs. I also put short strips where the "j" channel will go later to keep that area clean. With the tape barrier on all sides of the rib out about 3/16" this leaves enough space once the rib is clecoed in to run my finger along the rib, both sides and make a nice fillet. Some places have too much proseal and I scoop some up with a popsicle stick first. If I still have too much proseal along the edge , I just run my finger out on the tape and spread it there to get rid of it. Once a bay is complete, the last thing I do for that day is remove the tape. You end up with a clean job when you are finished and most fillets are even.
As for the ribs not fitting in easily, are you faceting the tip of all the ribs as per the plans? Are you sure you made your plywood cradle the proper size?This was my second set of tanks (RV-10) and I cannot say I had any issue installing the ribs. Yes you have to wiggle them in place. I place the skin in the cradle and start on one end installing the ribs. I start clecoing at the open end on both sides and work my way to the nose . At the nose a few holes do give a little concern, but I use an awl carfully and work the holes on place. Now if the flanges at the nose have not been faceted enough I could see where they would give you a problem as they would not allow the rib to go in the nose of the skin far enough for the holes to line up.
For me, tapeing up the skin to protect it from the access proseal is a must. Anywhere you do not want proseal I tape. I'm quite carefull so I only use a 1" wide strip of tape, some might need 2" tape.
Hopefully some of my tips may help you. Just a thought, when you had a rib dry clecoed in the skin , did you look at the skin in the very nose to see if it had little bumps from the flanges of the rib?
Ron
 
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Just reading Walts post, that would work fine but to let you know how easy it is I did all ribs in one tank at a time in one session. If memmory serves me correctly it was in an evening. The tapeing was already done and everything was preped. Getting preped and having every thing ready and planned out is key.
 
Thanks for the advice guys. It helps that I am seeing what is normal. Walt - yes I know the rivets just need to be slightly squashed, but that was not as easy as I thought it would be. I tried to use my pneumatic squeezer first, but then went with the heavy hammer/c frame per plans. The #6 rivets that came with my kit were way too long so I ground then down on my sanding disc and maybe that hardened them. Anyway, I think the pop rivets will work fine and be much easier to install and the hole in the middle will be well covered with pro-seal on the inside. Ron - I was considering using tape, so it sounds like that works well for you, I'll do that too. I was concerned my cradle might be too tight so I took them apart and opened the contour slightly so they are not too tight to allow rib installation. Nose flanges have been well faceted. They are really very smooth now and don't cause any resistance at all. The resistance is in the bend of the skin. The nose area is bent to give a nice radius at the leading edge, but no contour is there for the different bend radius for upper vs lower wing contour. That is created by the ribs and is a little difficult to get the .032 skin to form around the rib in a jig (cradle). I think the pro-seal will make things a little slippery and maybe go in a little easier. After yesterday's indoc, I wish I wouldn't have pro-sealed the outside of the rivets holding the fuel flanges. If fuel gets to that point, the primary - interior pro-seal job I did wasn't very good.

Thanks for the help gentlemen.
 
I set the 3/16 rivets in the end rib tooling holes with my 3X rivet gun turned up to 90 psi, and a tungsten bucking bar. Just make sure the rib is well secured. I clamped the rib web in my bench vise, with the rivet as close to the jaws as I could get and still get the gun on it.

I too spent several hours assembling the first tank the first time. Have faith; it gets easier every time you do it.;) Here's a detailed description of the best way I found to assemble an RV-7 tank. The final assembly is probably the easiest of all, as the sealant tends to lubricate the rib.

Hope this helps!
 
Miles,
Great idea - clecoeing the forward hole from the inside. I'll try that when I put my ribs back in. I got the stiffener angles, fuel cap flanges, and fuel drain flanges fay-sealed under clecoes today. Did the 3/16" rivets too - using pop rivets. I'll rivet these items in tomorrow and then start on the ribs.

Thanks
 
Scuffing & Cleaning

Hey, Scott, I'm sure you've done this in your prep, but be sure you scuff up the mating surfaces of the ribs/skin and clean, clean, clean with Acetone, MEK, etc. until the cloth is white with no residue.

Also, I used Rick's method on fay sealing. Last night I installed the five interior ribs on my right tank in about two hours. Like others said, be sure your cradle is fabbed properly, and work from the open end down to the nose to line up and cleco. On mine, after the first cleco or two, everything else lined up fine. But, practice again dry before doing it with Pro-Seal. Not sure about the 14, but on my tanks the skin fits tight, as it should (not tight enough for a rubber mallet though!). Maybe it's just me, but after everything is dimpled and buttered up with Pro-Seal, it all seems to go together better than dry, so if you get the process to work dry, you'll do fine with it wet. Good luck and enjoy the process.
 
Jim,
Thanks for the advise. I taped lines on both sides of all rivet hole locations and used a maroon scotch bright 'wheel' I found somewhere mounted in my die grinder and scuffed up all rivet lines and rib flanges. I use both MEK and acetone for final cleaning after I've cleaned everything with warm soapy water and let it dry for a couple days. The spec says it will take about 64 hours to tack dry at 77 degrees, 114 hours to cure. My basement where I'm building is 65 degrees, so it will take longer. Things I sealed 3 days ago aren't sticky anymore, but they are definitely not cured. I used a horse syringe (22 cc) and that works very well for putting the sealant on, but refilling it every few pieces takes time. JT (moderator & local RV guru) suggested I use a zip lock bag like a cake decorator. Take a heavy duty ziplock bag, turn it inside-out, put your hand in the bag, grab the ball of mixed sealant like a baseball, and turn the bag bag right-side out, capturing the sealant, then zip it shut. Cut the corner and you have your cake decorator. Kind of like picking up a dog turd..... except the dog turd smells better..... I think I'll do this, but I might try to use it to squirt some sealant into the syringe. The syringe will work great for putting a small blob of sealant on the backs of the rivets.
 
I used a similar method with the syringe. I buttered the top and front of the ribs with the popsicle stick, cleco'd in place, then when all the ribs were cleco'd on top, I used the syringe to run a bead over the rib locations on the bottom of the skin. After clecoing the bottoms of the ribs I then used a trimmed acid brush to form the fillets and put a dollop of ProSeal on the shop heads.

I'm sure the ziploc bag will work fine. I just never found a reason to do it that way since I had the syringes.

I'm building mine in my garage workshop typically heated to approx 60F. I plan to rivet the right tank tomorrow, which will be a day and a half since I set everything with ProSeal. Based on my experience with the left tank, I could easily be setting rivets on Sunday or Monday and still be okay. Now if it was last Summer it would be a different story. I think working with ProSeal is definitely a Winter sport! :D

Oh yeah, you're probably smarter than me, but be sure you run your vent line and drill the hole on the root rib for the vent fitting BEFORE riveting the root and tip ribs in place. I was able to make it work okay on the left tank doing it bass ackwards, but much easier doing it the right way.
 
For the stiffeners and ribs, I like to use acid brushes with the bristles trimmed down to 1/4" to 3/8" to make it stiff enough to spread the sealant. It does a nice neat job with no masking and little cleanup.
FP02102012A0004V.jpg


I found some 60cc syringes at drugstore.com that I like to use to apply the bead for the baffle. The opening is a full inch in diameter, making it relatively easy to load.
 
Miles, you must have taken that picture using your feet! :D That's one thing I haven't yet been able to do -- pull out the camera and take pics with wet ProSeal in progress.
 
Miles, you must have taken that picture using your feet! :D That's one thing I haven't yet been able to do -- pull out the camera and take pics with wet ProSeal in progress.

:D:D
It upsets my wife when I get primer overspray or sealant on the camera, so I just have her come out and take those pictures. If I'm in the picture, she took it.;)
 
I set the 3/16 rivets in the end rib tooling holes with my 3X rivet gun turned up to 90 psi, and a tungsten bucking bar. Just make sure the rib is well secured. I clamped the rib web in my bench vise, with the rivet as close to the jaws as I could get and still get the gun on it.

I too spent several hours assembling the first tank the first time. Have faith; it gets easier every time you do it.;) Here's a detailed description of the best way I found to assemble an RV-7 tank. The final assembly is probably the easiest of all, as the sealant tends to lubricate the rib.

Hope this helps!

Ya know Miles, you could finish that project much quicker if you would quit stopping to take all those photos.:)
 
Ya know Miles, you could finish that project much quicker if you would quit stopping to take all those photos.:)

You might be right Ed, but even though I'm not nearly as old as you :p, I still have trouble remembering things from one day to the next. When I go to build a second component, the camera helps me remember how I built the first.;)
 
One way I found to get the ribs clecoed to the skin (I am quite lazy, finding easier ways to do things is my calling) was to push the skin only about 1/3 of the way into the jig, leaving the rear edges a foot or a little more apart, then installing the first (nose) cleco on the top and bottom of each rib. Then just push the skin a little farther into the jig and install the next cleco in each rib. After 2 or 3 clecoes are in place on top and bottom, you can usually push the skin all the way into the jig and finish clecoing. Piece of cake. I had a lot of practice, built my left tank 3 times before I had one that didn't leak.
 
You might be right Ed, but even though I'm not nearly as old as you :p, I still have trouble remembering things from one day to the next. When I go to build a second component, the camera helps me remember how I built the first.;)

Good point Miles...but then you have to remember that you took the pictures...before you start on the second one:eek:
 
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