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Tip: Alternative to Proseal

joeboisselle

Well Known Member
I see here on the forums from time to time frustration with applying pro-seal or having it fail in one way or another. I've built 4 tanks for my -4, and on the 4th try I used something different. I didn't mention it here at the time, as I wanted to see how long it would hold before I admitted that I have this in my RH fuel tank, :eek: but after six years it's still holding. I used green loctite 290 on every rivet and laid a bead along each rib/back plate before installing. Soaked 'em. The tank has endured 100+ deg heat and single digit cold, left empty for a few months and filled again... and not one drop has leaked out in Six years.
YMMV
 
That _ is _ cool.

Did you build the tanks 'dry', and add the loctite after all riveting was done? Even the back baffle?

What paint products did you use for finishing?

Auto fuel?

Ethanol?

Do you do acro on a regular basis? (Flexes/stresses joints more)

What did you do in the 'large gap' areas, like the noses of the end ribs, & the corners of the back baffle?

BTW, thanks for starting this thread in the 'general' section; I only monitor a few of the sub-forums on a regular basis. I'd have missed it completely.

Charlie
 
. . .BTW, thanks for starting this thread in the 'general' section; I only monitor a few of the sub-forums on a regular basis. I'd have missed it completely.

Charlie
Charlie, just a note on this. If you click on the "Today's Posts" link at the top left of the site you will see every new post that was submitted since your last visit (assuming you were logged in) regardless of which thread it was posted in. You would never miss ANY post by following the forums this way.
 
That _ is _ cool.

Did you build the tanks 'dry', and add the loctite after all riveting was done? Even the back baffle?

What paint products did you use for finishing?

Auto fuel?

Ethanol?

Do you do acro on a regular basis? (Flexes/stresses joints more)

What did you do in the 'large gap' areas, like the noses of the end ribs, & the corners of the back baffle?

BTW, thanks for starting this thread in the 'general' section; I only monitor a few of the sub-forums on a regular basis. I'd have missed it completely.

Charlie

I applied the loctite to the ribs before cleco-ing them to the skin, then dipped each rivet before installing. The back baffle I did the same but after it was riveted together I used the loctite as a slosh and kept adding until it wouldn't leak through. I honestly don't remember what I did for the nose ends of the ribs, I'll have to pull the wing root fairing off to look. I'm guessing pro seal.
No auto fuel
No ethanol
Gentleman acro
Imron paint

At any rate I had green fingers instead of black sticky everything and it worked.
 
Interesting info, thanks!

Reading this:

http://www.loctite.sg/sea/content_data/93808_290EN.pdf

It appears it is resistant to leaded fuel and ethanol over long periods of time (5000h per the data sheet), so that's a good sign.

Does "pro-seal" act as a "glue" that also enhances strength, or is it just a sealant?

The loctite seems to cure solid, which you'd think could be a problem if/when the wing flexes repeatedly over time ...
 
Thanks for the info, both about the assembly techniques and from kamikazi on the ethanol issue.

K, proseal sealant does 'act' like a glue, but it isn't rated for, or intended to be used as, a structural adhesive. I can't see into the minds of the Van's engineers, but I seriously doubt that it entered in their strength calculations when designing the tanks.

Armed with joe's info, it's tempting to build myself a small (2-5gal) transport tank dry & try the 'wicking' method of sealing it, just as an experiment. If we could build the tanks totally dry, and wick the sealant into the seams & rivet holes after assembly, that would be a huge time and mess saver.

Charlie

Edit: Thanks to Steve, as well, for the tip on reading new posts.
 
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I'd still like to hear the theoretical perspective on using something that cures solid for this purpose ... I'm not expert, but that seems potentially risky ... though of course, seems to have worked out OK for the OP!

Different uses might impact the result though ... how much flex in an RV wing?
 
I'm going to say the only flex on a tank is going to be from temperature changes. Way too many pieces in there to allow any flex during flight. I have no idea what the capabilities are of the loctite are in terms of flexibility. Perhaps because I don't usually leave the tanks empty, the fuel inside keeps the aluminum at a fairly constant temperature.
Charlie, there are a few different "green" loctite flavors... if you do try an experiment, maby try a couple of 'em...
 
...,
proseal sealant does 'act' like a glue, but it isn't rated for, or intended to be used as, a structural adhesive. I can't see into the minds of the Van's engineers, but I seriously doubt that it entered in their strength calculations when designing the tanks.

....

The Grumman repair manual uses 'proseal' as a structural adhesive, along with 3/32 NAS1097 rivets as a repair technique for all bonded areas, not just fuel tanks.
 
The Grumman repair manual uses 'proseal' as a structural adhesive, along with 3/32 NAS1097 rivets as a repair technique for all bonded areas, not just fuel tanks.

Same exact part number? The company makes structural adhesives too.

And even if it is the same part #, I notice: "along with 3/32 NAS1097 rivets" mentioned in that description. Why bother with the rivets?

I'm not saying that it won't work as an adhesive; it obviously will. I used the Flamemaster brand to install my NACA vents. But it isn't designed for or intended as a structural adhesive by the mfgr.

Charlie
 
I'm going to say the only flex on a tank is going to be from temperature changes. Way too many pieces in there to allow any flex during flight.

Aircraft structures (like most structures) continuously bend and flex during flight, no such thing as a "rigid' aircraft.
 
There are a few (maybe only one) datapoints for Green Locktite. It may be *the* answer, but I'd rather wait to use it until 50 airplanes have been flying successfully for 20 years with it as a sealant.

I put a lot of faith in tens of thousands of existing aircraft fuel tanks that were successfully sealed with proseal.

The biggest cause I've seen for proseal failure was poor mixing technique. I helped a couple of airport neighbors with a weeping rivet on their airplane. They attempted to seal it with proseal, but it wouldn't cure. Later, I examined their mixing cup and it appeared that they hadn't been thorough when they mixed the batch. We cleaned off the goo from inside the tank, thoroughly mixed a new batch of proseal (from the same cans), applied it, and it cured in a couple of days.
 
Loctite 290

Loctite 290 also will Florese with UV light so once wicked you may be able to identify it on inside of tank.
 
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