Tank sealant in a modern mooney

[Schllc]

I thought I would poll the experts for their opinions....

I acquired a 2009 mooney and am preparing to have it painted. 
the logs show a few minor tank sealant repairs, but nothing major. 
I owned a 2005, and a 2007 for several year and these also required a few minor repairs. 
I read a lot about wet wing tank sealant deterioration, but it mostly seems to be an issue with older mooneys. 
I also read if you are going to paint, do the tank reseal prior. 
while I don’t want to spend money on something completely unnecessary,  I also don’t want to pass on the opportunity, just to save a few bucks. 
the sealant is only 10 years old at this point, and I would think there have been large improvements in the durability of the sealants used. 
anyone care the share their expertise here?

[philiplane]

The sealants available today are the same spec as they were 40 years ago. It's not the sealant that is the problem, it's that people vary the application process and you then get premature adhesion failures. And pinholes due to inadequate mixing of the sealant, or using the fast setting version where is is setting up as it is still being placed.

[buddy]

I faced the same problem when I had my 1980 M20J, I had a couple of Small sealant repairs made 20 years later and thought that was the end of my leaks and got the plane repainted. Shortly after the new paint job I developed another fuel leak and brought it to Wet-Wingologists in Ft. Lauderdale and had Emerson reseal both wings and he did a great job with a good guarantee. I was lucky the leaks didn’t do any damage to the new paint. Long story short I would have the wings resealed before you get it repainted.

[LANCECASPER]

4 hours ago, Schllc said:

I thought I would poll the experts for their opinions....

I acquired a 2009 mooney and am preparing to have it painted. 
the logs show a few minor tank sealant repairs, but nothing major. 
I owned a 2005, and a 2007 for several year and these also required a few minor repairs. 
I read a lot about wet wing tank sealant deterioration, but it mostly seems to be an issue with older mooneys. 
I also read if you are going to paint, do the tank reseal prior. 
while I don’t want to spend money on something completely unnecessary,  I also don’t want to pass on the opportunity, just to save a few bucks. 
the sealant is only 10 years old at this point, and I would think there have been large improvements in the durability of the sealants used. 
anyone care the share their expertise here?

I had heard that early in the Acclaim (‘07 ish, so it would apply to Ovations after that as well), Mooney had an improved procedure to apply sealant under the cross pieces of the tank as it was being built, helping to keep things sealed better. Maybe someone else with better knowledge of this will chime in. I think @Hank had a post about this a long time ago.

That being said it might not hurt to take it to an expert and have them inspect the tanks with cameras  before you paint it.

[carusoam]

Top surfaces of the tank are at risk over the years...

Tank sealant deterioration is highly temperature dependent. Empty tanks in the hot sun, on a windless day, can get pretty hot...

Tank stripping is best to do before paint.... some tank stripping has been known to be paint stripping too...

There are three or four tank people around the country...  Houston, Florida, Wisconsin... fill in the blank here...

Finding where leaks are is a real chore...

Finding if you have leaks is pretty much a digital affair... there is or there isn’t...

 

My tanks lived in Arizona for a few years... when my PPI was completed, the top access panels were stripped and re-sealed... and the paint scars haven’t healed yet...  

 

There isn’t a real answer to the best way to handle this... but... if it ain’t broke... is a good one.

Resealing a tank to go another 25 years isn’t a terrible investment, if you wanted to do it... (perfect for a new2U forever-plane)

Spending money on Cies digital gauges is another way to improve things... (Better use of money, plus it can tell if you have a leak... in some cases.)

 

How soon until the paint is scheduled?

How soon does the plane go in the shop for annual or other maintenance...?

 

Simple leak test...

Fill the tanks to the top... max it out to have fuel against as many access panels as possible... use the side of a hill when filling it...

Don’t fear fuel leaking out the vent like a C152... the vents are way up hill in our low wings...

Tiny leaks will leave a big blue stain... easy to find with the inspection panels removed...

Removing inspection panels?  Great time to install Cies digital fuel gauges...

If the plane had a history of leaks... cleaning the old blue stain out is probably a good idea... every year, you will have a discussion with your new mechanic about how those stains have been there a while...  

PP thoughts only, not a mechanic...

Best regards,

-a- 

 

[Gagarin]

Later long fuselage Mooneys are sealed the same way is done on Jet planes. Sealant is applied to the tank parts just before assembly so the sealant is sandwich in between the structure creating a very strong sealant bond. 

[jetdriven]

In theory, yes. But in real life, they use cheap acid brushes from Harbor freight, they mixup the sealant and use it as it’s setting up before they get the pieces put together, or they do not mix it properly. I’ve been to the factory, and the same woman who was doing tanks in 1979 is still doing them in 2005, and they leak five years later.

[DonMuncy]

If you can take your plane to one of the top resealing guys, like Houston Tank Specialists, they can inspect and give you an opinion as to the likelihood of a need for a reseal. But even then, it is still an opinion. Any Mooney tank can start leaking tomorrow, or may not leak for a long time. Having had leaks patched in the past tilts the odds in favor of more leaks, but it is still "a tilt", not a certainty. 

[ArtVandelay]

When you get your plane painted, ask for them to fill a rattle can with the paint your using for future touch ups. Good news it won’t show because it will be on the bottom.


Tom

[PT20J]

8 hours ago, ArtVandelay said:

When you get your plane painted, ask for them to fill a rattle can with the paint your using for future touch ups. Good news it won’t show because it will be on the bottom.


Tom

Sounds like a good idea, but... The paint will be 2K (paint + hardener). You can get 2K rattle cans, but once you activate it, it will go bad after about a day. And, wear a respirator so isocyanates in the hardener don't wreck your lungs -- it's nasty stuff.

Edited November 26, 2019 by PT20J