Pro Seal

[Freemasm]

Is there a published or rule of thumb expected ?dry? life for Pro Seal? What should I look for regarding wing tanks that weren?t built yesterday? Any info/help/experience would be appreciated.

[wirejock]

What is "dry life"?
Cure time varies with mix and temp.
Figure at least 2-3 days. A week or more is better before adding pressure to test.

[Freemasm]

Originally Posted by wirejock

What is "dry life"?
Cure time varies with mix and temp.
Figure at least 2-3 days. A week or more is better before adding pressure to test.

Tanks kept full of fuel last longer between reseals. If you seal tanks/pass leak test, how long can they reasonably stay dry/exposed to air before the sealant developed issues? Long story-short, thinking of buying some QB wings that have been sitting for quite a while.

[TShort]

I hope it's forever ... I finished my slow build tanks in 2007 and they've been sitting (empty) since!

Curious to see answers to this ... I never thought about it being an issue.

[fixnflyguy]

I built my tanks in 1995, and they didn't see fuel until 2009. No issues. I work with Proseal nearly every day, and it is quite amazing if it's applied properly, with very little that degrades it.

[NYTOM]

Originally Posted by fixnflyguy

I built my tanks in 1995, and they didn't see fuel until 2009. No issues.

Thank You
I can?t tell you how much happiness your answer gives me. Been praying for a response like yours.

[Freemasm]

Here are some excepts (italicized) from the Product Expert at PPG. Super informed (not always the case these days), personal, and helpful:

We make no claims as to service life, and there is nothing in the material specs to which we certify that would duplicate sealant that has been fuel immersed, then dried for a long period of time.

As you are aware, the preferred method of aircraft storage is to keep some fuel in the tanks. This keeps the sealant from drying out and shrinking. (this also goes for the other types of elastomers in the fuel system such as O-rings etc.)

From my experience in the Industry over many years, a lot of how well the sealant does in long term aircraft storage is predicated on the original seal design that was used. OEM’s that specified thicker fillets, and used a more redundant seal design in their tanks will be less prone to leaks upon refueling.

Wow – you have a Mooney that doesn’t leak? Incredible. I deal with all aircraft that use Pro-Seal and PRC sealant, Mil, Commercial, and GA. Other than the first series of B-1b bombers, the Mooney seems to be one of the most leak prone aircraft. (my edit here, Mooney's have very stiff landing gear. The tribal knowledge in that community is to keep the tanks full and stay off of rough fields)

The Mooney materials engineer had to have come from Lockheed Burbank, because your plane is sealed the same way as the Conni, Electra and P-3 …and for that matter the F-117.

There are some people out there that use Shell 1010 oil over the seals, but the USAF materials guys advise against this, and neither Boeing, or Airbus approve either.

FYI – B-52’s are all over 50 years old and 80% of the sealant is still original (and these planes have like 36 feet of wing deflection). (My edit here, deflection probably isn't the problem. Mooney gear are very stiff. Sharp accelerations like hard landings and taxiway bumps are the probable Mooney culprits.)

All that said, if I had newly fab'd tanks and knew it would be a while before they were put into service, I'd probably have some fuel sealed in the tanks; reference the B-52 comment. We can assume they're always fueled. Just because they don't leak immediately after a long dry time/wait doesn't mean you haven't affected the sealant life.

Probably won't help me in my hunt but if this saves anyone some rework, all good.

Cheers Boys.