Sealing fuel tanks

[1524J]

Hey all! I know this topic has been discussed numerous times, but I'm looking for specific info from those who have acutally performed a reseal. Our Mooney is down for an annual and we decided to bite the bullet and perform a complete strip and reseal. I've reseached quite a bit already but would still be interested in any tips or advice. I've decided to go w/ SR125A for the stripper and Flamemaster for the sealant.

[Shadrach]

If you're going flamemaster use CS3204 in the tank and CS3330 to seal the access panels.

 

Bring a lot of patience to the job...

 

[Piloto]

Get a good reclinable creeper and a couple of gallons of MEK. Also plenty of cotton rags. No matter how much you try it is a messy job. To reduce your frustration make sure you perform a low air pressure (no more than 2psi) leak test before putting any gas in the tanks. The tanks should be airtight.

José

 

[Mooney65E]

Plan on doing some paint work to the underside of the wing where the stripper oozes past the access panels. It'll get pretty messy...just keep it contained, keep your cool and you'll be glad you tackled the job yourself.  Nearly 10 years ago I machined two cover plates from .250" aluminum that covered the lower access panels. I drilled and tapped one hole in each and installed a brass sprinkler fitting on the inside of the outboard panel. On the bottom of the inboard panel I installed a return line which drained stripper fluid to a metal tub where it was recirculated through a submersible pump back to the sprinker/spray head inside the wing tank. About 5-6 hours and we were completely rid of the old sealant and ready to apply the new (we also used Flamemaster). Ten years later and the tanks haven't leaked a drop!! We passed the pump, tank and panels around the airport to other Mooney owners wanting to reseal their tanks. Not sure what ever happened to them or who has them now, but it's not too terribly difficult to rig another one up.  Take the thousands of dollars you saved and spend it elsewhere on your plane.

[Scott Aviation]

Quote: Mooney65E

Plan on doing some paint work to the underside of the wing where the stripper oozes past the access panels. It'll get pretty messy...just keep it contained, keep your cool and you'll be glad you tackled the job yourself.  Nearly 10 years ago I machined two cover plates from .250" aluminum that covered the lower access panels. I drilled and tapped one hole in each and installed a brass sprinkler fitting on the inside of the outboard panel. On the bottom of the inboard panel I installed a return line which drained stripper fluid to a metal tub where it was recirculated through a submersible pump back to the sprinker/spray head inside the wing tank. About 5-6 hours and we were completely rid of the old sealant and ready to apply the new (we also used Flamemaster). Ten years later and the tanks haven't leaked a drop!! We passed the pump, tank and panels around the airport to other Mooney owners wanting to reseal their tanks. Not sure what ever happened to them or who has them now, but it's not too terribly difficult to rig another one up.  Take the thousands of dollars you saved and spend it elsewhere on your plane.

[1524J]

I quess it would help if I gave ya'll (yes....I'm in Texas....ya'll) some idea of what I know to this point.

1. Removing the access panels. I know Don Maxwell has an article in MAPA stating they use a sharpened putty knife and a dead blow hammer to gently work around the access panel until it comes loose. I have spoken w/ others that say there is a lip just inside the access panel and it's best to use a heat gun to soften the adhesive until it releases. The heat gun worries me because I'm not interested in bubbleing the paint but at the same time, I certainly don't want to damage the lip that may be lurking just inside the access panel.

2. I purchased four of the 6oz. sem kits of CS3204B and two of the CS3330 for the access panels as well as a quart of 1005 for the top coat. I plan on doing one tank at a time and am uncertain if I've got the quantity I need to finish at least one tank. I also plan on thinning the CS3204B w/ Tolulene to make my own Class A sealant that I can brush on when I've finished filleting the seams.

3. Although it's a moot point.....I decided to go w/ the SR125A vs the Polygone. After speaking w/ several people, I was told it would take anywhere from five to fifteen gallons of Polygone to complete both tanks and the SR125A would only take two gallons for both tanks. The SR125A costs around $95 a gallon and I had to purchase a case which contains 4 gallons. The Polygone was about $175 for a five gallon bucket of gel coat. Seems that the SR125A must be a stronger concentrate than the Polygone although I have not verified this.

4. I plan on taping off the bottom of the wing around the access panels and seams to try and prevent too much damage to the paint. Another reason I went w/ the SR125A, it has the consistancy of syrup and my thinking is it may not migrate though the seams as easy as a liquid. I'm going to try to be very careful w/ the MEK when cleaning up the remaining sealant.

Thanks for the replys......ya'll.

[Mooney65E]

Quote: scottaviation

 Mooney 65E

Hi, Im currently in the process of stripping and resealing my fuel tanks in my J and am looking at using RPM polygone stripper, I am wondering what type possibly make and model of circ pump and person would use to circulate the stripper through the tanks without eating or damaging the pump components, its a big job and don't need the headache of going through 2-3 pumps to finish the job.  Great idea by the way.

 

Thanks,

 

Chris

[triple8s]

I too have been thinking about the dreaded reseal job. I even went so far as to ask a friend who has lots of Mooney parts for a couple of old tank panels so I could experiement with ways of removing the sealant. After messing with them I decided I would put it off a bit longer and just pay to have the resealed.  So this solvent will dissolve the old sealant enough so that it will wash out? What about the residue and the fuel system? Are there any unusual issues if you have aux tanks? Should you strip and reseal all the tanks if only one is leaking? The only real leak I have is the left Aux tank just outboard of the left MLG, I usually just put a bit of fuel in it when filling the mains to keep it wet, unless if I am going on a long trip. The aux tanks were put in in the late 80's, on average how long does the sealant last?  

[DaV8or]

Seems like the next guy to build a pump striping system needs to post up the part numbers of all the stuff that is known to work. Maybe pictures too. A call to LASAR might help, because even though the state of California won't let them do it anymore, I hear Paul Lowen is the guy who invented the process.

[1524J]

Quote: triple8s

I too have been thinking about the dreaded reseal job. I even went so far as to ask a friend who has lots of Mooney parts for a couple of old tank panels so I could experiement with ways of removing the sealant. After messing with them I decided I would put it off a bit longer and just pay to have the resealed.  So this solvent will dissolve the old sealant enough so that it will wash out? What about the residue and the fuel system? Are there any unusual issues if you have aux tanks? Should you strip and reseal all the tanks if only one is leaking? The only real leak I have is the left Aux tank just outboard of the left MLG, I usually just put a bit of fuel in it when filling the mains to keep it wet, unless if I am going on a long trip. The aux tanks were put in in the late 80's, on average how long does the sealant last?  

[flight2000]

[Lood]

Could someone please enlighten me on why the fuel tanks are only sealed along the seams? My common sense tells me that it would be better to cover the complete inside of the fuel tank with sealant. My reason being that there would then be no edges between the sealant and metal which, in my opinion, is the perfect place for the Avgas to get in under the sealant should there be the slightest flaw.

[DaV8or]

[isaacpr7]

On 4/9/2011 at 5:07 AM, Mooney65E said:

Plan on doing some paint work to the underside of the wing where the stripper oozes past the access panels. It'll get pretty messy...just keep it contained, keep your cool and you'll be glad you tackled the job yourself.  Nearly 10 years ago I machined two cover plates from .250" aluminum that covered the lower access panels. I drilled and tapped one hole in each and installed a brass sprinkler fitting on the inside of the outboard panel. On the bottom of the inboard panel I installed a return line which drained stripper fluid to a metal tub where it was recirculated through a submersible pump back to the sprinker/spray head inside the wing tank. About 5-6 hours and we were completely rid of the old sealant and ready to apply the new (we also used Flamemaster). Ten years later and the tanks haven't leaked a drop!! We passed the pump, tank and panels around the airport to other Mooney owners wanting to reseal their tanks. Not sure what ever happened to them or who has them now, but it's not too terribly difficult to rig another one up.  Take the thousands of dollars you saved and spend it elsewhere on your plane.

I'm currently working on a similar sealant removal project. Can you remember how many gallons of sealant removal fluid you poured in the tank for recirculation? I just want an idea on how much I should buy. Also, how many GPH was the pump rated for?

[RobertGary1]

Of course the biggest thing to know is to not plug any of the tinny holes through the rib that allow fuel and water to flow. Plugging these can cause water to dislodge on rotation with terrible results. You can get some small s/s tubing to run through the ribs and seal around it.

 

You can do an enormous amount with patch sealing. My first quesiton would be if a strip is required. You can get great results by just slapping sealant on top of leaky areas.

Gospel here.. http://www.donmaxwell.com/publications/MAPA_TEXT/_overlay/Fuel%20Tank%20Repair_How%20We%20Fix%20Them%202-05.htm

-Robert

Edited March 29, 2016 by RobertGary1

[Hank]

But not if the old sealant is degraded and crumbly, like some of mine was. 

[TWinter]

Sounds tough...I think I'll wait and donate to the Jose' fund and get my long range tanks and reseal all done all at once.

Good luck, I admire the work and effort you guys are taking on.

[ryoder]

I paid 1900 and had them done right.  Full strip and reseal.  Don't go cheap and do a patch job.

[RobertGary1]

24 minutes ago, ryoder said:

I paid 1900 and had them done right.  Full strip and reseal.  Don't go cheap and do a patch job.

I disagree. Depending on the conditon of the sealant you can get decades out of patching. I wouldn't recommend the nuclear option unless the existing sealant is crumbling  Just leaking is normal maintenance patching for wet wings  

-Robert

[Guest]

I don't think that adding small s/s tubing is an approved method in AD85-24-03 or SB 230?

Clarence

http://www.mooney.com/en/sb/M20-230A.pdf

http://wwwapps3.tc.gc.ca/Saf-Sec-Sur/2/AWD-CN/documents/US85-24-03.htm

[RobertGary1]

8 minutes ago, M20Doc said:

I don't think that adding small s/s tubing is an approved method in AD85-24-03 or SB 230?

Clarence

http://www.mooney.com/en/sb/M20-230A.pdf

http://wwwapps3.tc.gc.ca/Saf-Sec-Sur/2/AWD-CN/documents/US85-24-03.htm

You'll want a field approval. 

-Robert

[ryoder]

39 minutes ago, RobertGary1 said:

I disagree. Depending on the conditon of the sealant you can get decades out of patching. I wouldn't recommend the nuclear option unless the existing sealant is crumbling  Just leaking is normal maintenance patching for wet wings  

-Robert

I guess it depends on how old it is.  Mine was 50 years old.

[Guest]

1 hour ago, ryoder said:

I paid 1900 and had them done right.  Full strip and reseal.  Don't go cheap and do a patch job.

It's hard to argue with the price. That's the cost of two of my main bladders alone.

Clarence

[1524J]

3 hours ago, RobertGary1 said:

You'll want a field approval. 

-Robert

 

3 hours ago, M20Doc said:

I don't think that adding small s/s tubing is an approved method in AD85-24-03 or SB 230?

Clarence

http://www.mooney.com/en/sb/M20-230A.pdf

http://wwwapps3.tc.gc.ca/Saf-Sec-Sur/2/AWD-CN/documents/US85-24-03.htm

When I sealed my tank I made a mark above the drain hole in the rib before sealing, that way you know where the hole is located and can clean it before the sealant dries. It's easy to seal over the hole and not realize it. Couple of other critical areas....make sure the vent tube is clear inside the tank, drain holes on either side of the sump drain, and pickup tube.