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fuel tank woes

Hey Jerry

If you mixed it 10 to 1, it will set up fine. Let it set in a warm area for 3 days, then balloon test it. After 3 days, the balloon will not hurt it, and you will know how well you did.

John Bender
 
Hey Jerry,

John's right...you should be fine. When you do the ballon test do not use your compressor, use a bike pump or a ball hand pump...it doesn't take much. Your compressor can blow out stuff that wasn't broken.
 
I keep my shop cool so I built a temporary heat box and put the tanks in it for a few days to get the sealant cured. Took about a week before I felt confident the sealant was cured enough to do the leak test.
 
JerryG150 said:
I reworked my fuel tank today. I used the qt. sealant can and mixed it 10 to 1 using a weight watchers scale for the weight proportions. I have a hunch my sealant will never set up. I must have messed up again. A note came with the qt. sealant

"that it will take up to 3-7 days to cure and will remain soft for up to 30 days in cool weather ... be patient! Van's"

The little jars and caulking tubes of sealant I used before, set up in about 2-3hours. I'll give this stuff a few days and see if anything begins to set up. Here's hoping it does eventually set up and then doesn't leak.

I'll be very surprised and happy if all goes well. May just have to build another tank.
Click to expand...
If worse comes to worst, Jerry, on page 4 0f this thread, "Chuckster" said he'd build one of these tanks, and leak test it for $200. It might be worth it ,to prevent the aggravation- just a thought. Steve
 
I too had good luck with the sealant. I let it cure for a week, then did the air test. I did have 4 small leaks. Two screws on the access cover and one each on the balloon attachment and air valve to hose attachment. I tweeked those 4 locations with a screw driver and the balloon stayed inflated for two days. I verified this by measuring the circumfrence of the balloon with a seamstress tape.

Art Pennanen
 
Balloons are a good test, BUT...

You guys using the balloon method of testing need to be aware that the ambient barometric pressure will affect the size of the balloon. If the barometric pressure goes down, the size of the balloon will increase. Another point is that all balloons have "some" leakage. If possible, you should inflate another balloon from the same package and compare it to the ones in the test. If both go down the same amount, you should still be good to go.
 
gonna wait a week!

Well I finished my redo on the gas tank yesterday. Re-riveted the top on with the help of a few larger "oops solid pop rivets" from Wicks. It's always been a problem for me to drill out rivets.

I've learned the qt. container of tank sealant from Van's Aircraft cures much more slowly then their tiny jar and caulk tube of tank sealant. When I used the small quantity containers it was so hard in an hour I had to toss whatever was remaining. With the sealant in the qt. container I can work much more slowly.

I'll wait at least a week before I test it with the balloon test kit. I've already vented the tank lid so I guess I'll cover it with a some Saran Wrap or something similar before I do the balloon test.

We'll see ... :eek: :eek:
 
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I had a problem with mixing the sealant properly, the 1/10th on the hardener is difficult to measure because of the low weight. If you go to the Flamemaster website and look at the product spec sheet for CS3204, they recommend mixing 10 to 1.0 by weight, or 10 to 0.83 by volume. the 0.83 is not too hard to measure if you use syringes. 30CC of base material and 2.5CC of hardener makes a nice batch for one page of instructions. Get some 30CC syringes and a couple of 3CC syringes at a ranch supply or feed store, and use a band saw to cut off the front of the syringes at the first graduation. I toss the 30s and re-use the 3.
 
GDS
All you need is digital scale from Walmarts. They measure down to 0.1 of a gram, so it's easy to get your 10 to 1 ratio by wieght for any amount. Top it off with some cheap drinking cups and some popsicle sticks and mix away.

Art Pennanen
 
Agree

Use a small plastic container of sorts. Zero the scale with the container on it, and put in the sealant and use a calculator to determine the balance needed.

John Bender
 
Been useing the wal-mart scales for years, that's what makes it so easy to get leak proof gas and oil tanks. All I build is riveted tanks! And for all the folks that think gas in the cabin is a bad thing(yes, in the wing is better)have you ever flown a Cub, Taylorcraft, Champ, Chief, etc?
 
fiberglas tanks

I wonder who builds the tanks for the S19? I doubt Rans does, he must contract out to someone.........Just a thought.
 
Part three:
Tested after re-stuffing the screws with goop and the sight glass held!!! no leaks were detected. Have re installed the top and will re test again in about a week. (cold here). Will post new test results at that time.
Dick
 
Balloon Test Completed

I completed the fuel tank balloon test today. I have good news and bad news. The good news is my grandson will have a lovely small bag of balloons to play with when he comes to visit in a couple of months. :) The bad news is my tank window still leaks even after my repair job. :(

I don't want to do this tank business again. I estimate I spent about $100.00 on fuel tank sealant alone. My fault for not ordering the qt. container of fuel tank sealant to start with. :eek: I guess it'll be about $100 (just a guess ... I'll let you know Monday) to order a new tank and I'll probably go with the Chuckster (earlier post this thread ...$200.00 labor job and worth it :)) to do my tank once and for all.

I think, with my experience on my first tank, my second attempt would be successful but why go thru all that aggrevation again. :( I'm not an engineer, far from it, but I don't understand the reason for putting 55 holes in an aluminum gas tank for a window guage when I could have used a "stick" placed down into the tank like I do on all the other LSA I've been flying.

At least 20 tanks are airborn and fuctioning fine having been built properly ... guess I'm still an inexperienced builder even after 900 hours. I know I'll forget about this tank experience completely once I have the RV grin.:D
 
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tank sealant

I used the small jars a number of times and the "caulking tube size" 2 to 3 times. I also bought the caulking gun from Van's for the tube size. Lots of wasted product in the "caulking tube size" because I only needed a small amount from time to time. Both of those containers of fuel tank sealant set up much more quickly than the qt. size.
 
Jerry

That is why I asked. The quart size you hand mix sets up much slower, and you should be able to seal up the window easier. Sorry you're having problems.

John Bender
 
what's your opinion?

This morning I was going to dissemble my gas tank for a second time. Then I had an idea. I mixed up another batch of gas tank sealant and filled in the whole window area (all 55 holes) with sealant. In a few days when it cures I can either use my Dremel with a tiny round brush dipped in laquer thinner and try to clear the windows a bit ...or leave it completely covered with the sealant and go EAB instead instead of ELSA.


If my tank holds air with the 55 holes sealed, should I leave it and go EAB? Or should I salvage what I can from my tank, bite the bullet and spend away? :confused:
 
Jerry,

Sorry you are having trouble. You asked for opinions so here is mine. DO IT CORRECTLY. Take the tank apart and ensure you have sealant between the pieces. Putting some just on top, in my opinion, is asking for a leak down the line. You certainly do NOT want fuel in the baggage compartment.

Ensure you are mixing the sealant correctly. Buy the quart size and use a gram scale. Do not try to guess or proportion it by volume.

After disassembly, remove all of the old sealant completely and scuff the sealing areas very well.

Maybe some of the others can chime in with a few more hints for you. And find an experienced RV builder that has built the tanks for any of the RVs as the sealing process is pretty much the same. He/she should be able to help with the next assembly.
 
Jerry

Mostly agree with Marty. Don't try to use thinners of any type on that plastic. Will ruin it for sure. Get a new window, and clean everything up well inside and out around the window area, and try to find an experienced builder in your area, and have them help you. If you had everything ready, it is an hour or two's job. If you don't like the window later, you can close it then.

John Bender
 
Part four
Tested yesterday and found top to be secure since re install. However a very tiny slow leak bubbled up in sight glass at one hole location. I suspect it didn't show up under test three as it was impossible to get much pressure in tank with the top clecoed on.
Will remove two adjacent screws re goop again and install the two screws. Will test again in one week.
 
has anyone eliminated the window?

Several people have expressed an interest in eliminating the window. Has anyone actually done it yet? If so, did it solve the problem of leaking?
 
Closed the window

In the midwest, ethanol is common. Knowing that, I did not want to chance a SECOND problem with a leaking cracked window. I closed the window and put in a marine fuel gauge on the top. NO LEAKS, and I can turn around IN FLIGHT, and see how much fuel is in the tank. It moves around some, but that is great. If it is bobing between 1/2 and 3/4, and your dash says 13 gals - you are just fine. The other window can not be seen while flying. Also, you can see how much fuel you are putting in while filling it. Both made it worthwhile for me. Very satisfied.

John Bender
 
Mark Henderson said:
Several people have expressed an interest in eliminating the window. Has anyone actually done it yet? If so, did it solve the problem of leaking?
Click to expand...

Quite a few of us have. Obviously John did. I prosealed a piece of aluminum over mine. Its only there for a preflight visual. Now I use a stick just like I used to with my Comanche. And I don't have to worry about the plastic breaking and gushing into my cabin in flight. No...everyone's doesn't leak, everyone's doesn't break...but enough have and still are for me to eliminate the problem. Like John, I'm satisfied.
 
Thanks for the feed back. I have to say it is tempting to build it to start with with a solid plate instead of the window. I wish van's offered this as an option. There have been enough changes that have come down after we built something that it does not seem like a significant modification. The adell clamps over the rudder have been replaced by a metal guide as an example. And frankly, other than the builder no one would ever know if you replaced the window at the beginning or 5 hrs after the first flight.
 
tanked the tank ... thank you

After removing the top of my gas tank once previously, then having regooped the window perimiter (without removing the window), removed and regooped all the screws and nuts, reriveted and regooped the top, let it cure and then having failed the next balloon test, I really didn't want to rip the top off a second time.

So after that failed balloon test, on the exterior of the tank, I applied a heavy coat of uncompressed sealant, uncompressed like the two cutouts located on the top/sides on our gas tanks, on all 55 holes (all the windows and screw holes) in the window area. Then let it cure a few days, plugged a single top rivet allowing a few molecules on air to excape and so far after 12 hours with a fully inflated balloon test proceeding as I type, everythink is A-OK. Finally.

I then purchased a thin wooden dowl which, I believe (can't check it out now) will easily act as a gas tank dip stick. Since I've dipped every gas tank in every LSA I've ever flown since 2006, dipping doesn't bother me.

I thought it would cost about $100.00 to replace all the parts to build a new gas tank not counting fuel cap, filler neck, rubber sleeve and 2 large clamps. WRONG. All those parts less the above actually cost about $325.00. OUCH. (Obviously there are some other parts that can be salvaged too.

So where did I go wrong? I'm beginning to think I messed up by literally following steps 4 & 5, section 37-05. Both steps say to apply a thin layer (a relative term, to say the least) of sealant to ... blah, blah, blah. I wish it would have said ... apply a thick, or heavy or 1/16" thick layer or more than adequate layer of sealant to the blah, blah, blah ... . A more experienced builder than I, would have understood what was needed or meant and proceeded accordingly ...

The Builder's Assistance at Van's has resolved every problem I've ever thrown their way. And there have been quite a few, I assure you. This tank problem will be resolved too.

If I have to build a new tank :( ... that's life ... but I hope I won't have to because my balloon test is now almost 13 hours old and still A-OK. :)
 
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Welded aluminum tanks?

I've been following this thread with great interest for some time. I started building an RV6A several years ago but didn't finish, at least in part, because I couldn't face building the fuel tanks. I was surprised to learn that Vans was still using riveted tanks with Proseal (goo) on the RV12. I know there are many who will defend this design for a variety of reasons, but it frankly seems antiquated and wrong to me. I visited the Zenith factory last November and saw some beautiful welded aluminum fuel tanks. They were feather light and I can't see how they would ever leak. I don't want to start a controversy, but if Zenith can do it why not Vans? Am I missing something?

Cheers, Jim
 
Jim McDonald said:
I visited the Zenith factory last November and saw some beautiful welded aluminum fuel tanks. They were feather light and I can't see how they would ever leak. I don't want to start a controversy, but if Zenith can do it why not Vans? Am I missing something?
Click to expand...

Sorry, but I have personally seen several of the Zenith tanks leak due to cracks where the tubing is welded into them.

On the other hand, I've built quite a few riveted tanks for RV's and other designs over the last 20 years and have never had a problem with leaks.

Just my experience.
 
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Hey Jim

The site glass has been the root of most of the problems. Without it, sealing the tank is not too bad at all. Almost every problem has been with the 'glass' area. That does require some serious planning or experience. Most 12 builders had/have neither. I also feel ethanol ( potential ) and plastic are not a good mix.

John Bender
 
leaking fuel tanks

Why not take it to your local Heli arc guy and have it welded? I plan on welding mine if I can talk my DAR into it being better and safer.

RV-4 flying
 
2024-T3 is not considered a weldable aluminum for aircraft use, most welded tanks are made from 6061, 5052 or 3003. I would not weld the -12 gas tank.
 
Ted Farmin said:
Why not take it to your local Heli arc guy and have it welded? I plan on welding mine if I can talk my DAR into it being better and safer.

RV-4 flying
Click to expand...

As Chuck said 2024 is not weldable and you will not find a welder who can weld the long seams in 0.025 thick aluminum, our ex-NASA welder will try at 0.040 and would prefer 0.060 for fuel tank welding.

Best regards,
Vern
 
part five:
re tested and the glass still leaks at the same place. Have purchased new glass components from Van and will go back to the beginning. Pull top, (2nd time) remove glass and goop and install new glass with sufficient goop between the glass and tank (I hope). Will also pull access plate at front (2nd time) as putting the vent tube clamps back on when re assembling the top is a bear if that isn't done.! Will have to wait for new top rivets to re assemble. Will re test and post results in about two to three weeks.
The really interesting part about all this is I expect that I may finish the airplane completely in two to three weeks and not have a usable tank by that time.
I will remain positive in my outlook to encourage the gremlins in the tank to co-operate.
Dick
 
dick seiders said:
part five:
re tested and the glass still leaks at the same place. Have purchased new glass components from Van and will go back to the beginning. Pull top, (2nd time) remove glass and goop and install new glass with sufficient goop between the glass and tank (I hope). Will also pull access plate at front (2nd time) as putting the vent tube clamps back on when re assembling the top is a bear if that isn't done.! Will have to wait for new top rivets to re assemble. Will re test and post results in about two to three weeks.
The really interesting part about all this is I expect that I may finish the airplane completely in two to three weeks and not have a usable tank by that time.
I will remain positive in my outlook to encourage the gremlins in the tank to co-operate.
Dick
Click to expand...

Dick, don't forget to goop the screws. I gooped the threads with enough goop that when I inserted the screw there was goop under the heads. Goop the nuts and the washers also.

I commend you for the positive attitude! Good luck! Keep us posted.
 
Balloon Leak test

My original balloon test leaked, but I could not detect where because it leaked very slowly. I wanted to eliminate the fill tube and gas cap as possible leaks. What I needed was a balloon with a large neck that would fit over the T-1204B flange on top of the tank. I found such a "balloon" at the local pharmacy. I put a wide rubber band around the flange first to act as a gasket under the "balloon". Then put a second rubber band over that followed by electrical tape and a clamp. Broccoli comes wrapped with rubber bands that are perfect for this. There are no leaks now. Can anyone think of a good caption for the photo? LOL
yzphfk5

As for the sight glass, I used plenty of sealant between the glass and the tank wall and also completely filled the threads of the screws. I discovered that the screw holes in the tank skin are slightly undersized. Instead of drilling them out, I forced all of the screws in. If not bottomed out, the screws will stay in place without the need for tape as described on page 37-05 step 3. After placing the glass over the screws, I filled all of the slots in the glass with sealant. There is no need to put sealant between the T-1213-1 Backing Plate and the glass because fuel needs to flow into the hollow space to indicate level. Sealant on the nuts and the ends of the screws is more for corrosion protection and thread locking than for leak prevention.
Joe
 
If your "balloon" remains inflated for more than 4 hours, you should call your Doctor!
 
4 washers?

These replies are timely as I am gooping away, here in Scotland.

The plans call for 4 x NAS1149FN632P washers on every screw around the sight glass. That's 88 washers. I don't think that many were provided. Is it really 4 washers per screw? If so, why?

Thanks...Keith
 
One washer per screw

I looked at the picture, 37-05 Figure 1, and did not notice the 4x. I think it is a mistake in the plans. I used 1 washer per screw.
Joe
 
Hey Keith

Are you working with latest revision ? I think they provided plain nuts, and you were supposed to re-use some of the washers.

John Bender
 
Revision 3 is current

Yep, I'm on 37-05 rev 3, which specifies 4 washers per screw. I did get the screws in the care package but no washers (as noted by Jerry previously). I'll go with one washer per screw from my stock of AN960-6, and defer applying more goop until tomorrow, in case anyone else thinks 4 are required.

Thanks...Keith
 
gblwy said:
Yep, I'm on 37-05 rev 3, which specifies 4 washers per screw. I did get the screws in the care package but no washers (as noted by Jerry previously). I'll go with one washer per screw from my stock of AN960-6, and defer applying more goop until tomorrow, in case anyone else thinks 4 are required.

Thanks...Keith
Click to expand...

The 4X is a typo. Should just be 1X
 
Removed top of tank and old sight glass and reinf. bracket. Pro sealed and installed the new sight glass and bracket 2/21. I really loaded up the proseal and when finished it oozed out of most of the sight glass holes. Looks really ugly, but may work. I have let the tank cure since and am going to re install the top tomorrow. Will allow about a 10 day cure time and then do the dreaded leak test. Will post results at that time.
Dick Seiders
 
Hey Dick

If you are not in any hurry what so ever, you can wait 10 days. I'd suggest putting the tank in a warm area for 3 days after finished, then do the balloon testing. If you mixed the 'goooo' well, you won't blow it out after 3 days. If all is well, empty it, and let it set a few more days to make yourself feel better. The stuff will be set up well enough after 3 days in a warm area to let you know how well you did.

John Bender
 
Thanks John. The problem is the temp in my garage is about 55 during the day, and 25 overnite. It's cold in Atlanta this winter. I wouldn't take the smelly thing in the house or would get in a bit of trouble. Thanks for the tip though. I may run a test after 5 or 6 days.
Dick
 
Try to find a large cardboard box. Set it over the tank and place a 100W light bulb inside.
 
Hey Dick

After a few hours, it really does not smell that bad. We have a nice house, but I took it inside and put it in a spare bedroom. Could barely smell it walking by. I put it up high to be the warmest. It works. You are corect, if it is in the 20'2, or 30's, it will take a long time to cure.

John Bender
 
Cardboard box oven

Good suggestion, Mel. I cooked my fuel tank in a cardboard box with a 60 watt bulb. My attached garage does not get much below 50 degrees. One could wrap the cardboard box with a blanket, too. Just make sure that the bulb does not contact anything flammable.
If a builder has doubts about the sight-glass, he could fill the tank with water before putting the top of the tank on. Then if there are any leaks, it would be easier to repair without the top in place.
I predict that Dick Seiders' tank will not leak around the sight-glass because he used plenty of sealant. Good luck Dick.
Joe
 
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