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  #1  
Old 09-25-2017, 06:31 PM
RA9A RA9A is offline
 
Join Date: Mar 2012
Location: Denver
Posts: 14
Default On going fuel leak

I have a RV9A with quick built wings I have had a ongoing issue with fule leaks at the root fairing rib and the back side of the tank I clean and put new tank sealant then after a while it starts leaking again
Has anyone had a similar issue and suggestions how to fix this issue for good
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  #2  
Old 09-25-2017, 07:26 PM
pa38112 pa38112 is offline
 
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Location: Clarksboro, NJ
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I may be reading this wrong, but it sounds like you are sealing from the outside?
Proseal will get soft when exposed to fuel/air cycles. It needs to be in the tank and stay wet to seal effectively. You will not find that written anywhere, but it has been the experience of several people including me.
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  #3  
Old 09-25-2017, 08:27 PM
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az_gila az_gila is offline
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
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Quote:
Originally Posted by pa38112 View Post
I may be reading this wrong, but it sounds like you are sealing from the outside?
Proseal will get soft when exposed to fuel/air cycles. It needs to be in the tank and stay wet to seal effectively. You will not find that written anywhere, but it has been the experience of several people including me.
And is covered by Vans "Tank Repair kit"

http://vansaircraft.com/cgi-bin/stor...ct=&action=add

It's a disk held on by proseal and 24 closed end pop-rivets to cover a 5 inch hole in the rear baffle that allows access to get inside to seal the rear baffle to skin joints.

One kit per hole, my RV-6A has five fuel bays, not sure how many bays between the ribs that your RV-9 has.
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  #4  
Old 09-26-2017, 05:15 AM
RA9A RA9A is offline
 
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Location: Denver
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Thank you for your reply you are reading it correctly I have been trying to fix it from the outside I will get ahold of Vans for the repair kit
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  #5  
Old 09-26-2017, 08:09 AM
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RVbySDI RVbySDI is offline
 
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Location: Tuttle, Oklahoma
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Here is my story. Maybe you can find some info in it:
http://www.vansairforce.com/communit...uel+tank+leaks

If not, here are some other stories you can read that may help:
http://www.vansairforce.com/communit...rchid=33031817
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  #6  
Old 09-26-2017, 10:01 AM
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ArVeeNiner ArVeeNiner is offline
 
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Here's my story too but the photos have broken links due to a change in the Photobucket policy. I can send you them if you need them.

http://www.vansairforce.com/communit...d.php?t=122300

If it looks like your leak is in the bay closest to the wing root there may not be a need to cut a hole in the rear baffle. You may be able to access it from the plate that is already there like I did. No leaks for over 2 1/2 years.
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  #7  
Old 09-27-2017, 05:54 AM
RA9A RA9A is offline
 
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Thank you for your reply I was hopeing I could do it from the outside if you wouldn't mind sending some pictures that would be great my e-mail is RV9ARD@msn.com thank you
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  #8  
Old 09-27-2017, 07:35 AM
rv7charlie rv7charlie is offline
 
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Location: Pocahontas MS
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Does anyone have any documentation from a sealant mfgr that polysulfide won't remain sealed if it's not constantly in contact with gas? If this is a real hazard, surely the mfgrs would document it. I'd even expect the FAA to be speaking up, with AD's and advisories. There are thousands of certified a/c using polysulfide in their tanks (and to seal their fuselage pressure vessels), and many are decades old & sit unflown for months or years at a time.

I've got a -4 that was built in the early 90's. The sealant is soft in places, and I've had a few leaks. The original builder had leaks, too, when the plane was young.

I've resealed small leaks in the root ribs (at the nose reinforcing angle) of both tanks, from the outside. When I did the repairs, I removed as much of the exterior proseal as I could, and then tried to clean the area with popsicle stick scrapers, picks, etc and MEK soaked bits of paper towel, etc to get into the crevices. Then applied new proseal on the outside of the joints & over the rivet heads.

One side is still holding up fine after 3 years; the other has another leak near the top of the angle. The plane often sits for a month or more at a time, and usually with less than full tanks.

After doing the repairs, someone mentioned that it's difficult to 'contain' the effects of MEK around cured proseal; that it will damage sealant near where you're actually working. I don't know if that was my problem, but I'm suspicious that it was. My next attempt will involve mechanical removal, followed by something that will clean the surface but won't attack the adjacent proseal.

Since one side is holding up, and the other isn't, I have to blame my technique, on the side that isn't holding up.

My totally unqualified opinion is that leaks are 99%+ due to contamination of the surface being sealed. And an in-use tank is a lot harder to clean properly than a new one.

Just my no major motel chain last night opinion. Always happy for new data, with supporting evidence.

Charlie
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  #9  
Old 09-27-2017, 08:22 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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Quote:
Originally Posted by rv7charlie View Post
Does anyone have any documentation from a sealant mfgr that polysulfide won't remain sealed if it's not constantly in contact with gas?
Not that I am aware of, but I don't think anyone here has ever said that sealant has to be kept in constant contact with fuel.

What has been said (and known for decades) is that if sealant is in constant contact with evaporating fuel in a normal air environment (as can occur on the exterior of a tank with a long term leak) it will begin to soften and turn to mush. There is lots of discussion in the archives.
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  #10  
Old 09-27-2017, 09:12 AM
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mikehoover mikehoover is offline
 
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I had a leak at the inboard root rib bottom corner where a lot of pro seal is needed to fill in. I removed the fuel sender plate (yes, painful) and worked plenty of pro seal in at the leak area. Fine ever since.
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