Fuel Tank Sealant Project

[PT20J]

I never heard of this for fuel tanks. But I took the poster's advice and looked into it. EPC stands for Epoxy Flooring Compound. According to the manufacturer, Sealbond, it's "Ideal for floor protections of new and existing flooring of food processing plants, chemicals and pharmaceutical factories, sugar and oil refineries. Recommended for installation of anti-skid coatings indoor. For patching of deteriorated flooring. High performance coating system."

Not sure about airplane fuel tanks, but it sounds like a good product to use on my hangar floor.

Sealbond-EFC-100-Epoxy-Flooring-Compound.pdf

[LANCECASPER]

21 minutes ago, PT20J said:

I never heard of this for fuel tanks. But I took the poster's advice and looked into it. EPC stands for Epoxy Flooring Compound. According to the manufacturer, Sealbond, it's "Ideal for floor protections of new and existing flooring of food processing plants, chemicals and pharmaceutical factories, sugar and oil refineries. Recommended for installation of anti-skid coatings indoor. For patching of deteriorated flooring. High performance coating system."

Not sure about airplane fuel tanks, but it sounds like a good product to use on my hangar floor.

Sealbond-EFC-100-Epoxy-Flooring-Compound.pdf 1.49 MB · 0 downloads

There actually was a aircraft tank sealer called EPC-100 that was used in Boeing 707s. It could very well have been the same product as the floor adhesive.

I can only imagine how difficult it would be to get epoxy off of the Mooney fuel tank seams. Just replace the wing . . lol

[N201MKTurbo]

4 hours ago, LANCECASPER said:

I've never even thought about tackling a tank, but he is telling the original poster to "look into it" which is probably not going to happen 13-1/2 years later, unless it's time to re-seal them again .

Plus he is suggesting a product that isn't mentioned in the Mooney Maintenance Manual (EFC-100), which apprarently is nearly impossible to remove when that time comes. 

Plus he is implying that polysulfide is being used to seal the tanks, when in reality it's what Weep No More and Wet-Wingologists use to remove sealant. https://www.rpm-technology.com/wp-content/uploads/2016/12/PolyGone-310-AG-Inst-v2.pdf

Other than all of that misinformation, i agree that prep being paramount is true on this and any other tedious job.

Our tank sealant is polysulfide. I have some on my left arm right now. The stripper that removes polysulfide is PolyGone.

[N201MKTurbo]

EFC 100 is polyurethane. I thought everybody decided it was a nightmare.

[N201MKTurbo]

https://www.meggitt.com/wp-content/uploads/2018/06/EFC100.pdf
 

This is the stuff, not the floor coating.

[LANCECASPER]

12 minutes ago, N201MKTurbo said:

Our tank sealant is polysulfide. I have some on my left arm right now. The stripper that removes polysulfide is PolyGone.

My mistake. I read the reference too quickly.

[PT20J]

22 minutes ago, N201MKTurbo said:

https://www.meggitt.com/wp-content/uploads/2018/06/EFC100.pdf
 

This is the stuff, not the floor coating.

Ah, apparently there is a difference between EFC-100 and EFC100. My mistake - I just searched for the string referenced in the post. Thanks for the clarification.

[MikeOH]

3 hours ago, N201MKTurbo said:

https://www.meggitt.com/wp-content/uploads/2018/06/EFC100.pdf
 

This is the stuff, not the floor coating.

Hmm, glad I've got the MS cognoscenti to set me straight not to use it on Mooney tanks; just reading that brochure makes one think it's pretty good stuff compared to our polysulfide tank sealant.

However, Meggitt has clearly fooled the military into using it on the KC-135, C-130, KC-10, ... 

[McMooney]

hmmm, looks really good to me,  know what i want for my next reseal

[EricJ]

11 hours ago, MikeOH said:

Hmm, glad I've got the MS cognoscenti to set me straight not to use it on Mooney tanks; just reading that brochure makes one think it's pretty good stuff compared to our polysulfide tank sealant.

However, Meggitt has clearly fooled the military into using it on the KC-135, C-130, KC-10, ... 

Apparently it's awesome until something needs to be repaired or reworked, or even worse, stripped.   Then you're screwed.

[Fly Boomer]

59 minutes ago, EricJ said:

Then you're screwed.

Is that the technical term?  

[MikeOH]

2 hours ago, EricJ said:

Apparently it's awesome until something needs to be repaired or reworked, or even worse, stripped.   Then you're screwed.

I guess I'm just an old engineer that likes to work with an open mind.  Fundamentally, it's hard for me to believe that there has been NOTHING better developed since Mooney built our planes using polysulfide tank sealant.  Next, it's clearly been adopted, on a large scale, by the military; my experience with them is that a ton of qualification testing is required on a new product. Hard to believe they didn't evaluate maintenance, along with everything else.

Next, what is the real field data?  Do you have first hand experience for your comment? Know someone personally that has tried it and had a horrible experience? Or, is this a 'he said, she said' situation?  Or, just internet speculation skepticism? (Nah, that would never happen)

It seems the big advantage of this stuff is that it does NOT deteriorate like polysulfide.  So, I'm not following why rework or stripping would be required. That leaves repair. I'm curious how often a wing is damaged enough to require the sealant to be removed and reapplied that hasn't already totaled the wing?  Not saying this stuff isn't tenacious, but I think that might actually be more of a feature and benefit

[McMooney]

what i was thinking, if the wing is damage to the point where you need to remove this, it's probably scrap.

the example above was to replace the spars,  i'm sure that's in replacement wing territory

[LANCECASPER]

2 hours ago, MikeOH said:

I guess I'm just an old engineer that likes to work with an open mind.  Fundamentally, it's hard for me to believe that there has been NOTHING better developed since Mooney built our planes using polysulfide tank sealant.  Next, it's clearly been adopted, on a large scale, by the military; my experience with them is that a ton of qualification testing is required on a new product. Hard to believe they didn't evaluate maintenance, along with everything else.

Next, what is the real field data?  Do you have first hand experience for your comment? Know someone personally that has tried it and had a horrible experience? Or, is this a 'he said, she said' situation?  Or, just internet speculation skepticism? (Nah, that would never happen)

It seems the big advantage of this stuff is that it does NOT deteriorate like polysulfide.  So, I'm not following why rework or stripping would be required. That leaves repair. I'm curious how often a wing is damaged enough to require the sealant to be removed and reapplied that hasn't already totaled the wing?  Not saying this stuff isn't tenacious, but I think that might actually be more of a feature and benefit

Read the entire post that I quoted from yesterday. Follow it all the way through and see what others were having to go through (15,000 psi water jet) to try to remove this sealant which is not called for in the Mooney Maintenance Manual.

There is a good reason that they stopped using this on Mooneys and according to one or more of the posts, the military stopped using it also.  Paul Beck from Weep No More who knows more about Mooney tanks than almost anyone on here, told the individual that they have had no success in removing that type of sealant with their methods.

Look up the FlightAware data on the airplane of the individual who posted. Three and a half years  later he still doesn't have it back in the air. 

Our tanks flex. There are two kinds of wet wing tanks: (1) those that currently leak and (2) those that will eventually leak. On paper it may look great to put a "lifetime" sealant on them. It's easy to say that if this sealant ever fails then just put in bladders. What if you're covering over some unnoticed corrosion when you apply this? What if you have to deal with spar cap corrosion and have to remove the skins like this gentleman was trying to do? The corrosion was repairable but he couldn't get to it. If someone other than him was doing the work and charging $100/hour, due to the cost involved, the wing, or maybe even the airplane, would be considered totaled, depending on the value.

Part of owning a wet wing airplane is resealing the tanks every 25 years on the average, if you're maintaining it properly (good shock discs, keep fuel in the tanks, etc). It's easier to factor that into reserve expenses than using something that was already used by Midwest Mooney (out of business) on roughly 100 Mooneys and turned out to be a complete disaster. To add insult to injury Midwest charged 50% more than the other options at the time. I wonder why we don't hear about them anymore.

Thankfully that 2020 post warned the rest of us about using it. There are a couple ways to learn: 1) Make the mistake and never do it again (costly tuition)  2) Learn from the mistakes of others (almost free).

 

 

This post is proof that no matter how horribly bad of a sealant or patch job was done, it can be brought back to new if they didn't use a product that is not recommended:

 

Here's a post from 2011, back when Midwest Mooney was still in business and urethane was still considered an option. I think @Hank ended up getting his tanks sealed at WetWingologists and is probably glad he made that choice.

 

[N201MKTurbo]

Some useful information.

So it looks like if you were going to use this on a Mooney tank, you need to seal it with polysulfide and then cover with EFC. At least the big gap spots like the back corners. It looks like for a repair, you can put EFC over EFC.

efcguide.pdf

[N201MKTurbo]

Looks like the Navy is going to pay someone to develop a process for removing the stuff.

https://govtribe.com/opportunity/federal-contract-opportunity/e-6b-sealant-removal-and-replacement-n0001923rfpreqapm2710068synopsis

 

[Hradec]

Not long ago somebody contacted me when they took they Mooney to Fort Lauderdale  to get their tanks redone. Unfortunately  they had this efc100 in their tanks. I told him what I did and told is tank guy to contact me. 

Apparently 15,000 psi water jet is needed to remove this garbage. 

I was replacing my spar cap.  I used a propane torch to heat a thick metal putty knife. The hot blade removed excess polyurethane where it was thick and needed to be removed to remove and install hiloks and rivets. A heat gun was also used along with a temp sense gun to not over heat the metal. 

I did no remove all of it, just where it was disturbed to facilitate structure repair. Before I came up with this technique,  I disturbed the whole tank.

I ended up coating the entire tank with the seskents and process called out in the mooneys manual. 

Plane might be test flown before the end of the year.

Glenn 

[EricJ]

2 hours ago, MikeOH said:

Next, what is the real field data?  Do you have first hand experience for your comment? Know someone personally that has tried it and had a horrible experience? Or, is this a 'he said, she said' situation?  Or, just internet speculation skepticism? (Nah, that would never happen)

See the link on the mooneyspace thread where this was experienced and discussed here previously where it was discovered to have been applied to Mooney tanks.

[LANCECASPER]

1 minute ago, Hradec said:

Not long ago somebody contacted me when they took they Mooney to Fort Lauderdale  to get their tanks redone. Unfortunately  they had this efc100 in their tanks. I told him what I did and told is tank guy to contact me. 

Apparently 15,000 psi water jet is needed to remove this garbage. 

I was replacing my spar cap.  I used a propane torch to heat a thick metal putty knife. The hot blade removed excess polyurethane where it was thick and needed to be removed to remove and install hiloks and rivets. A heat gun was also used along with a temp sense gun to not over heat the metal. 

I did no remove all of it, just where it was disturbed to facilitate structure repair. Before I came up with this technique,  I disturbed the whole tank.

I ended up coating the entire tank with the seskents and process called out in the mooneys manual. 

Plane might be test flown before the end of the year.

Glenn 

I admire your tenacity! Best of wishes getting it back in the air

[MikeOH]

Okay!!  You all have convinced me!

When the time comes, it will be yesterday's technology for my tanks

[N201MKTurbo]

It always amazes me that we cannot accept that the best solution has already been discovered. A lot of people must think the people in the past were just stupid. Sure, we have made great strides in electronics, but when it comes to chemistry, I think most of the great discoveries were made a century ago.

[N201MKTurbo]

https://phys.org/news/2023-12-insights-metabolism-plastic-eating-bacteria.html#:~:text=Halopseudomonas bacteria live in the,for so-called polyester polyurethanes.

[MikeOH]

1 hour ago, N201MKTurbo said:

It always amazes me that we cannot accept that the best solution has already been discovered. A lot of people must think the people in the past were just stupid. Sure, we have made great strides in electronics, but when it comes to chemistry, I think most of the great discoveries were made a century ago.

And, it always amazes me the resistance and pushback against anyone who questions the status quo.

So glad to hear you, and apparently others, are so confident in your positions..."I think most of the great discoveries in <pick a field> were made a century ago.". SHEESH!

[Hradec]

1 hour ago, MikeOH said:

Okay!!  You all have convinced me!

When the time comes, it will be yesterday's technology for my tanks

The imperfectness of the original polysulfied sealant is probably the whole  reason they used it. Yes it may leak after 20 yrs, but if structure work needs to be done, solvents exist that will soften it to the point that plastic scrapers can remove it. The efc 100 polyurethane (at least in Mooney's)  is permanent, making structure repair and service if not impossible, at least very impractical. From what I recall in all my info gathering and talking to all the players, a couple hundred mooneys were ruined. 

[N201MKTurbo]

44 minutes ago, MikeOH said:

And, it always amazes me the resistance and pushback against anyone who questions the status quo.

So glad to hear you, and apparently others, are so confident in your positions..."I think most of the great discoveries in <pick a field> were made a century ago.". SHEESH!

You will never be satisfied with what you have.