RV7 Tanks - Open and rebuild or Build New

[APicard]

I have a set of build RV7 tanks that i'm trying to figure out what the best plan of action would be.

the previous builder added way to much Sealant and its making mounting the tanks a nightmare. (sealant where its not required along the spar mounting area of the tank, needed to be sanded off) These have also been sitting in storage since the mid 2000's without any covers so id like to make sure there is no unwanted friends hiding between the baffles.

Do i drill out the rivets and try to remove the rear plate off the tanks or do I bite the bullet and order new tanks?

 

[PaulvS]

I have a set of build RV7 tanks that i'm trying to figure out what the best plan of action would be.

the previous builder added way to much Sealant and its making mounting the tanks a nightmare. (sealant where its not required along the spar mounting area of the tank, needed to be sanded off) These have also been sitting in storage since the mid 2000's without any covers so id like to make sure there is no unwanted friends hiding between the baffles.

Do i drill out the rivets and try to remove the rear plate off the tanks or do I bite the bullet and order new tanks?

There is another option if you want to look inside and that is to cut round access holes in the rear baffle and then close them with the tank repair covers from Van's. But it should be possible to get an idea if anything is inside (I assume you mean mice) by shaking the tank. Maybe a borescope would work by snaking it through the filler and then the rib holes.
Ordering new tank parts there will likely be substantial wait times.
The excess sealant on the outside can be removed with polygone or paint stripper that contains methylene chloride (hard to obtain).

 

[PhatRV]

I have a set of build RV7 tanks that i'm trying to figure out what the best plan of action would be.

the previous builder added way to much Sealant and its making mounting the tanks a nightmare. (sealant where its not required along the spar mounting area of the tank, needed to be sanded off) These have also been sitting in storage since the mid 2000's without any covers so id like to make sure there is no unwanted friends hiding between the baffles.

Do i drill out the rivets and try to remove the rear plate off the tanks or do I bite the bullet and order new tanks?

Aircraft spruce sells the proseal stripper called Poligone. My friend used this stuff to clean up the old sealant before reseal

 

[[email protected]]

Just get some polygone and clean up where you need it gone so's they fit. Pressure test for leaks. If you can find/buy/borrow a flexible borescope to see the inside that would be great. If you are not sure they hold after the balloon test. Put 5 gallons of that blue gas in there and set in different attitudes to see if you get any stains. The balloon test is not perfect.
The last set of tanks I built tested perfect with air. Then after paint and install and putting vinyl stripping on them I got bubbles in the vinyl around some of the rivets. NO color or fuel leaking on any of the rest of the rivets, and cut the vinyl and no fuel just vapor. Go figure
You are going to wait along time for a pair of tank kits.
If they leak;;;; worst you can do is to open up the back of the tanks and put tank repair panels in place. Not really that big of a job.
They work great and will give you a very good look inside.
Van's probably has those in stock or you could make your own and use sealed pop rivets to close them back up.
Great time to do the SB on the fuel pick up lock and maybe even put in a flop tube for going upside down.
All that said::: I would not try to remove the rear panel. It would give me nightmares. Tons of work cause it is really stuck in there.
My luck varies Fixit

 

[fixnflyguy]

As others mentioned, clean the mating surfaces of excess sealant on the flanges so the tanks fit in place. I have done that for others using sharp plastic scrapers and scotchbrite without using any chemical removal that could contaminate the sealant. Use a cheap borescope through the filler neck and the fuel quantity sender plate to see general workmanship and sealing inside. last but not least if your satisfied there, cap the feed/vent lines and fill them with 100LL and let sit for a couple weeks. As others have also said, cutting open the backs for full inside clean and reseal is a fairly easy job. I've done a bunch of those. Here's a couple pics from various reseals of leakers. I cut the hole with a pin router bit, which takes a bout a minute each, then a quick clean-up with a drum sander. Others use a hole saw which also works well. I make my own plates from .050 or .063 2024. The sealed end pop rivets come from ACS and are cheap.

 

[Stuart Grant]

As others mentioned, clean the mating surfaces of excess sealant on the flanges so the tanks fit in place. I have done that for others using sharp plastic scrapers and scotchbrite without using any chemical removal that could contaminate the sealant. Use a cheap borescope through the filler neck and the fuel quantity sender plate to see general workmanship and sealing inside. last but not least if your satisfied there, cap the feed/vent lines and fill them with 100LL and let sit for a couple weeks. As others have also said, cutting open the backs for full inside clean and reseal is a fairly easy job. I've done a bunch of those. Here's a couple pics from various reseals of leakers. I cut the hole with a pin router bit, which takes a bout a minute each, then a quick clean-up with a drum sander. Others use a hole saw which also works well. I make my own plates from .050 or .063 2024. The sealed end pop rivets come from ACS and are cheap.

This all sounds like good advice. For future reference, just wondering if you can say more about the pin router bit technique. Was it carbide tipped for aluminum? About what diameter? Did you actually use it in a drill?

 

[fixnflyguy]

I liberated my pin-router bits from our inventory at day job doing heavy aircraft structures, though they are available from many different sources. It is self penetrating with a drill tip, and the flutes are made to cut. Yu can use a drill or a die grinder, but you must must learn the technique first. Penetrate the sheet perpendicular, then lay it over about 45 degrees and pull it along the cut-line. I like to use the the 1/8" diameter one which is a #1 bit. Here is an example of one from a well known aircraft tool supplier. https://www.browntool.com/Listview/tabid/344/ProductID/788/Default.aspx .

 

[APicard]

There is another option if you want to look inside and that is to cut round access holes in the rear baffle and then close them with the tank repair covers from Van's. But it should be possible to get an idea if anything is inside (I assume you mean mice) by shaking the tank. Maybe a borescope would work by snaking it through the filler and then the rib holes.
Ordering new tank parts there will likely be substantial wait times.
The excess sealant on the outside can be removed with polygone or paint stripper that contains methylene chloride (hard to obtain).

this will be my plan if i find anything with my borescope. my biggest issue is the excessive sealant.

 

[APicard]

Aircraft spruce sells the proseal stripper called Poligone. My friend used this stuff to clean up the old sealant before reseal

i will look into this stuff.