brian
Well Known Member
I pulled a fuel tank that had recently gotten more pronounced weeping/staining after several years of slight localized staining at one spot.
The proseal that is exposed on the outside has varying degrees of cure. The log books tell me this tank SB was done by the previous owner in 2010, just prior to selling to me.
After pulling the tank, I initially thought the person who did the SB work either used old proseal or didnt mix it well, because it looked like what was newer proseal was soft and sticky.
After looking at the tank more and starting to remove excess proseal from the outside, I'm starting to realize that the higher up on the tank, the more cured the proseal is, even in places where all the proseal I'm seeing would have been applied at the same time. In several low places (including where the seep originated) the proseal is very soft - so soft and gooey that it's like I just mixed it up a few minutes ago, and I can just wipe it off with a paper towel.
It seems unbelievable that someone would install a tank with such obviously uncured proseal, or that an A&P would sign off on such a thing. This tank has been in use in the 8 years since this work was done and an A&P signed it off.
So can something make this stuff somehow lose its cure? Perhaps it wasn't 100% cured in 2010 and since then the fuel in contact with it has caused it to lose its cure?
Here's a picture as an example of what I'm talking about. Look at the column of prosealed rivets for this rib. At the top, the proseal is pretty firm and dry. It gets softer and stickier as you go down the column, to the point where, at the bottom, I've wiped the rivet head, and some of the bottom rivets below it, completely clean, with just a paper towel and a bit of acetone. The outboard end, especially on the bottom, where the seeping originated, is the same way - with just a paper towel, I can wipe off big gobs of the stuff.
Can this mean this tank was installed with such uncured proseal? Or could the fuel somehow make the proseal lose its cure?
And most importantly, if something has made this proseal lose its cure, does that mean that the remaining proseal will continue to lose its cure?
I don't know much about ProSeal or its varieties, and I haven't worked with it before, so any help or insight you can offer will be greatly appreciated.
The proseal that is exposed on the outside has varying degrees of cure. The log books tell me this tank SB was done by the previous owner in 2010, just prior to selling to me.
After pulling the tank, I initially thought the person who did the SB work either used old proseal or didnt mix it well, because it looked like what was newer proseal was soft and sticky.
After looking at the tank more and starting to remove excess proseal from the outside, I'm starting to realize that the higher up on the tank, the more cured the proseal is, even in places where all the proseal I'm seeing would have been applied at the same time. In several low places (including where the seep originated) the proseal is very soft - so soft and gooey that it's like I just mixed it up a few minutes ago, and I can just wipe it off with a paper towel.
It seems unbelievable that someone would install a tank with such obviously uncured proseal, or that an A&P would sign off on such a thing. This tank has been in use in the 8 years since this work was done and an A&P signed it off.
So can something make this stuff somehow lose its cure? Perhaps it wasn't 100% cured in 2010 and since then the fuel in contact with it has caused it to lose its cure?
Here's a picture as an example of what I'm talking about. Look at the column of prosealed rivets for this rib. At the top, the proseal is pretty firm and dry. It gets softer and stickier as you go down the column, to the point where, at the bottom, I've wiped the rivet head, and some of the bottom rivets below it, completely clean, with just a paper towel and a bit of acetone. The outboard end, especially on the bottom, where the seeping originated, is the same way - with just a paper towel, I can wipe off big gobs of the stuff.
Can this mean this tank was installed with such uncured proseal? Or could the fuel somehow make the proseal lose its cure?
And most importantly, if something has made this proseal lose its cure, does that mean that the remaining proseal will continue to lose its cure?
I don't know much about ProSeal or its varieties, and I haven't worked with it before, so any help or insight you can offer will be greatly appreciated.
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