Tank seal... Issues afterwards

[Browncbr1]

12 hours ago, FlyingDude said:

Is that the cs3600? I don't get it: how will applying top coat fix today's leaks? Isn't it too late? A channel has already opened through the cs3204. How will too coat fix that? By seeping into the cracks?

Thanks.

As others have given you good advice, it is critical to let the sealant cure for about a week.  Temp and humidity impacts cure time. If you put fuel back in too soon, it will leak after a few days.  
 

the red honey is good for sealing tiny spots like pin holes or air bubbles.  Sometimes the leak entrance in the tank is a long long way away from the exit on the outside.  I had a leak at the aft wing skin lab joint that was actually coming from the top leading edge rib that was only leaking when tank was full.  

[JWJR]

Sealing compound/Top Coat fuel tank


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[JWJR]

The bubbles disappear as soon as suction is removed. You can rinse out all the soap and water out of the under wing fuel strainer hole. Remove the fuel strainer of course. Use a pump sprayer with water and a wet vac …rinse and clean all surfaces thoroughly and allow them to air dry before starting repairs.

Soapy water test is a MUST to find the leak. My advice is don’t skip it. How many top panels did you remove?
Cure time is critical- repair shops need room to get the next plane in for repairs and owners want their planes ASAP so they don’t have the luxury you do of giving it PLENTY of time to cure. Leave the top panels off a few days to allow air circulation into the tanks to dry the repairs/sealant then reinstall the inspection panels and leave the gas cap off to allow the sealant you used on the inspection panels some air. You can tape a screen over the inspection holes to keep bugs or debris from entering. After sufficient time install the wing fuel drain ( preferably a new one) and add fuel. Triple check the tank for any tools ,towels or debris before closing it up. There was a recent two person fatal in the northeast with a well known NASCAR driver.
They found what was left of a shop towel in the tank had resulted in a fuel clog. A good respiratory mask appropriate for chemicals is advisable too. A box fan
set up a few feet from the wing can help cure time /air circulation.

That’s all I got for you… best of luck … keep us posted


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[FlyingDude]

I just placed an order at SkyGeek... Bought pr1005-L, not cs3600. The PR is mentioned in the maintenance manual. 

I don't have top access panels. Only 2 bottom panels aft of the spar. Extended tanks are the 2 bays aft of spar, outboard of the bay with the gear bungee. That's why I can't observe soap bubbles while they're being generated. I'm thinking of getting some water soluble red ink and then viewing where it comes out of sealant on the inside...

I talked to my friend who's done tons of tank seals... He's in Europe, unfortunately. I wish he was close. Anyway, he says he's had success with sealant sticking on even uncleaned or poorly cleaned surfaces (they were urgent field repairs) because it sticks on the metal around the impurity, so though he says it's not an alibi to not clean it diligently, he says he's putting his money on improper mixing...

Yeah, I'll keep you guys posted. I should hang a "days without fuel leak" counter in my hangar. Lol.

Thank you all and cheers...

 

[Shadrach]

53 minutes ago, FlyingDude said:

I just placed an order at SkyGeek... Bought pr1005-L, not cs3600. The PR is mentioned in the maintenance manual. 

I don't have top access panels. Only 2 bottom panels aft of the spar. Extended tanks are the 2 bays aft of spar, outboard of the bay with the gear bungee. That's why I can't observe soap bubbles while they're being generated. I'm thinking of getting some water soluble red ink and then viewing where it comes out of sealant on the inside...

I talked to my friend who's done tons of tank seals... He's in Europe, unfortunately. I wish he was close. Anyway, he says he's had success with sealant sticking on even uncleaned or poorly cleaned surfaces (they were urgent field repairs) because it sticks on the metal around the impurity, so though he says it's not an alibi to not clean it diligently, he says he's putting his money on improper mixing...

Yeah, I'll keep you guys posted. I should hang a "days without fuel leak" counter in my hangar. Lol.

Thank you all and cheers...

 

3600 and PR1005 are the same mil-standard. They are interchangeable just like CS3204 and PR1422..  make sure you have 3204 or equivalent on hand. You do not want to repair solely with PR1005.

Get some small button lamp LEDs and a few blind spot mirrors from Autozone. You should be able to view all of the tank via the mirrors. 

 

 

 

[FlyingDude]

1 hour ago, Shadrach said:

3600 and PR1005 are the same mil-standard.

Cool. Great. Yeah, I ordered cs3204 too, the quart size.

Thanks for all the info...

[Prior owner]

Additionally, per FlameMaster tech rep, let the cs3204 sealant cure for DAYS prior to applying the cs3600 topcoat.

[JWJR]

If the original issue was mixing. I would recommend the tubes with plungers. Probably too late to change your order but the tube and plungers are designed for proper mixing.


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[carusoam]

The bubble test is to reveal exactly where the bubbles are entering…

This is exactly where fuel will be exiting….

DMax developed this procedure over years of working on Mooneys…

Trying to develop a new way is going to cost something…  more time, more effort, more money, more of something…

 

Bubbles stream pretty nicely through the hole…  even then the hole may be under the sealant, not where the bubbles are entering…  a sign that the sealant isn’t adhering to the substrate….

Use your least Favorite cell phone camera on one of the most simple tripod things found on eBay for taking pics of stuff for sale… anyone have an old phone they aren’t using?  They don’t make calls, but most of their other functions still work…

 

If you haven’t purchased a dental camera for inspections…. Now might be a good time….  Today you have a great reason to.

 

The amount of vacuum required is pretty minimal…. Remember, it’s only the weight of the fuel that is pushing the leak out… air is less viscous than fuel, it will flow very easily in comparison…

If you pull enough vacuum to collapse the wing skins…. A situation called oil canning… you might cause more sealant failures than you have already… so be careful with how much vac you pull

A side benefit for anyone that wants to be a maintainer of Mooneys… you have studied how to do things the way the guru of maintenance has done them… and you still have questions….  
 

This is a perfect opportunity to call DMax and see if he will take your call…. Ask him his recommendations to see inside the tank that doesn’t have inspection covers on top….  

I’d bet he takes your call, but doesn’t mention anything about putting ink in the tank…

My only phone call with DMax was an awesome 1/2 hour education about Mooney M20Rs… somewhere around 2009…

There are a few giants in the Mooney world… none are too busy to discuss Mooney challenges…

If Don isn’t available… DMax Jr. is aka PaulMax… is pretty sharp with Mooney maintenance challenges…

Expect when you see the video… you will notice things that you didn’t think were possible… stuff you thought would leak don’t… things you thought were air tight aren’t…

+1 on the magic of inspection mirrors… everyone should have them in their tool box as well…

Stay on target!  

PP thoughts only, not a mechanic…

Best regards,

-a-

[FlyingDude]

1 hour ago, JWJR said:

I would recommend the tubes with plungers.

That's what I had used the first time. I think I'll go with power mixing this time and not manual like I did in June...

[FlyingDude]

1 hour ago, PilotCoyote said:

per FlameMaster tech rep, let the cs3204 sealant cure for DAYS prior to applying the cs3600

Was that verbal info or is it written anywhere? I'm just curious why the instructions say that the cure time is 30 hrs for B1/2, and that B1/4 can hold fuel after 4 hrs? Anyway, at this point, I'll just wait a few days. That won't hurt anything. But I wish I knew this when I first worked on the tank :(

[FlyingDude]

1 hour ago, carusoam said:

If you pull enough vacuum to collapse the wing skins

I hope not!!!

Thanks for the tips. I will follow up :)

[carusoam]

11 minutes ago, FlyingDude said:

I hope not!!!

Thanks for the tips. I will follow up

By the way…

The power of the fuel pump…

If the tank vents get blocked…

The fuel pump draws enough vacuum to collapse the wing skins where the tanks are…. Before the engine runs out of fuel…. 
 

You can read about mud daubers around here… they use mud to build their nests… in interesting places…

Best regards,

-a-

[A64Pilot]

A few comments.

Dont use B1/2 use B2, just like epoxy you give up something for that fast cure.

When you use bulk product, you mix by color, it’s actually pretty easy, just use a tiny bit of the harder, it’s real easy to start with too much.

The tool to use to mix is a big screwdriver and a putty knife, and on a flat plate, a cup etc will have unmixed components stuck to the side that you can’t mix, but a flat plate you can mix every drop by scraping it clean and folding it over.

We had a couple Uber expensive mixers for the cartridges at the plant, that broke often, when it was broke we used an electric drill at slow speed to mix, without getting ridiculous you really can’t get it mixed too much, but when every bit is the same color it’s mixed as much as it needs to be. Cut the mushroom part of the plunger off to use a drill, small drill won’t work. Nothing wrong with doing it by hand though 

There is an expensive air powered application gun for the cartridges that is great, but the manual one like a caulk gun is pretty close and much less expensive

So long as it’s only been mixed for a short time, you can put excess in the freezer and that stops the curing, for up to 30 days? At one time at the plant we were buying it pre-mixed and frozen, stupid idea as the shelf life was much shorter so we ended up throwing away quite a lot of it.

[FlyingDude]

On 10/10/2021 at 10:00 PM, N201MKTurbo said:

I thin it a bit with MEK

How much MEK do you use to thin it?  What if the residue left behind after MEK evaporates jeopardize the quality of the sealant?  I had read somewhere else that they use acetone to cut it...

Do you have pictures of your work done with brush?  I just would like to see what to aim for...

Thanks a lot ...

[N201MKTurbo]

27 minutes ago, FlyingDude said:

How much MEK do you use to thin it?  What if the residue left behind after MEK evaporates jeopardize the quality of the sealant?  I had read somewhere else that they use acetone to cut it...

Do you have pictures of your work done with brush?  I just would like to see what to aim for...

Thanks a lot ...

Start with about 10% of the volume of sealant and add as necessary to get the consistency you need. I've never seen any degradation of the sealant from thinning it. 

If you are curious, mix some up and apply it to a scrap piece of metal and see how it cures.

A64 has a valid point about unmixed sealant. You can mitigate it in a cup by cutting the end of the stir stick off so it has a square end so you can scrape the corners. You can mix it up and then transfer it into another cup. This will eliminate any unmixed sealant doing this. You can usually get it all if you are diligent about it with a round end stick.

I've never used acetone, it would probably work. The sealant kind of smells of MEK, I think that is what they use as a solvent. Everything I have read said to thin with MEK.

[ArtVandelay]

These days, real MEK is hard to find, I see just MEK substitutes.

[N201MKTurbo]

Just now, ArtVandelay said:

These days, real MEK is hard to find, I see just MEK substitutes.

Go to auto paint stores.

[Shadrach]

56 minutes ago, FlyingDude said:

How much MEK do you use to thin it?  What if the residue left behind after MEK evaporates jeopardize the quality of the sealant?  I had read somewhere else that they use acetone to cut it...

Do you have pictures of your work done with brush?  I just would like to see what to aim for...

Thanks a lot ...

This was all done with a brush. It’s hard to say what the exact viscosity should be. I usually add MEK in several small increments until it is just brushable. It needs to be viscous enough to cling to the top of the tank without dripping.  The best way I can describe it is to transform it from a dough like consistency to a very thick batter.

Edited October 12, 2021 by Shadrach

[FlyingDude]

1 minute ago, ArtVandelay said:

These days, real MEK is hard to find, I see just MEK substitutes.

Amazon carries MEK/ butanone. That's where I ordered mine. The only item not coming from SkyGeek.. 

[Shadrach]

1 minute ago, N201MKTurbo said:

Go to auto paint stores.

Can’t get it in Maryland. Only the substitute. I have to drive into Virginia. It can be ordered online but it’s expensive.

[FlyingDude]

I got this. Too expensive? Couldn't find it at my regular hw stores in Michigan... 

DIYChemicals | MEK (Methyl Ethyl Ketone) | 1 Gallon (128 fl oz) (Shipped as 4X Quart Bottle) https://www.amazon.com/dp/B096SVGMN9/ref=cm_sw_r_apan_glt_fabc_0JCWPMMHTH48SM3E8249?_encoding=UTF8&psc=1

[Shadrach]

Also, if you want clean lines, it’s best to mask both applications. I created a line about an eighth of an inch from where the skin laps for the fillets. Tape removed before the sealant dries. I let the 3204 cure for three days (no longer tacky). I then masked a new line anywhere from an inch to an eighth of an inch off the fillets. I’ve then applied several coats of PR1005 again removing the tape before the sealant dried. Keep in mind the 1005 dries much faster than the 3204. It can get stringy like a spiderweb in short order. If this happens, don’t worry about it. Let it cure for several days.  Any “webs” are easily removed with a quick wipe with an MEK soaked lint free cloth. 

[N201MKTurbo]

4 minutes ago, Shadrach said:

Can’t get it in Maryland. Only the substitute. I have to drive into Virginia. It can be ordered online but it’s expensive.

I recently bought a 5 gallon can for $85. It should last me to the end...

California made it illegal, but that's California. It is because of its volatility. Of course we use it because it is a solvent that evaporates away cleanly. Most of the big box stores quit carrying it because they don't want a separate supply chain just for California. 

[Shadrach]

2 minutes ago, FlyingDude said:

I got this. Too expensive? Couldn't find it at my regular hw stores in Michigan... 

DIYChemicals | MEK (Methyl Ethyl Ketone) | 1 Gallon (128 fl oz) (Shipped as 4X Quart Bottle) https://www.amazon.com/dp/B096SVGMN9/ref=cm_sw_r_apan_glt_fabc_0JCWPMMHTH48SM3E8249?_encoding=UTF8&psc=1

I would just buy a gallon and be done with it. It’s good to have around and stores well when tightly sealed. $45 is chump change relative to the task you are embarking upon.