Fuel Tanks Log 
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 February 3, 2021

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Fuel Tanks
There are two 21 gallon fuel tanks on the RV-7. They are the inboard leading edge of the wing. The tanks consist of a 0.032 skin and several ribs. The rear of the tank is sealed by a baffle. Attached to this baffle at each rib location are the brackets that hold the tank to the spar. The skin of the tank is attached to the main spar and the leading edge skin by countersunk screws and platenuts. The tank is sealed with a compound that is known as Pro-Seal.
August 20, 2001 - 1 hours
Started marking and drilling the fuel tank attach brackets.

August 21, 2001 - 2 hours
Still drilling and laying out the fuel tank attach brackets.

August 26, 2001 - 2 hours
Countersunk the rivet holes where the platenuts attach to the fuel tank attach brackets. Started deburring the fuel tank ribs.

August 31, 2001 - 1.5 hours
Deburring fuel tank ribs.

September 1, 2001 - 4 hours
Fluted all of the fuel tank ribs, and riveted the platenuts to the left tank attach brackets. Started bolting the attach brackets to the left main spar.

Here are the fuel tank attach brackets bolted to the wing spar.

September 2, 2001 - 6 hours
Lined up and drilled the T-702 baffle to the tank attach brackets and ribs. Mounted the skin on the tank assembly and drilled all of the holes in the tank skin. Drilled and clecoed the stiffeners to the fuel tank skin. Countersunk the holes where the skin attaches to the baffle.

Fuel tank stiffeners drilled and clecoed to the skin.

Trial fit of the skin to the baffle and spar. I put a couple of the ribs in to make this easier.

Here are the fuel tank ribs clecoed to the tank baffle. I had to remove the wing leading edge to get those clecos in on the last outboard rib.

The tank is starting to come together. BTW that craddle doesn't work very well. The 2x4 is in the way.

September 3, 2001 - 5 hours
Fabricated the T-405 tank attach angle and cut out the T-410 reinforcement plates. Predrilled the cpacative fuel sender plates to the ribs and trimed the plates for the proper clearance. Drilled the access plate reinforcement plate to the inboard rib and drilled and clecoed the filler cap and drain flange to the tank skin. Started modifying the number two fuel tank rib for the inverted fuel pickup.

Fuel filler cap drilled and clecoed to the tank skin.

The newly fabricated T-405 tank attach angle with pilot holes drilled.

A very bad picture of the fuel drain flange drilled and clecoed to the tank skin.

September 6, 2001 - 3 hours
Finished the inverted tank mods to the second inboard rib. Countersunk the fuel filler body and deburred the skin and most of the ribs.

Here are the modifications that I made to the second rib of the fuel tank. The little door is there to keep the fuel from flowing backward through the rib, and the big hole is riveted closed for the same reason. This is part of the inverted fuel tank modification.

September 7, 2001 - 2 hours
Finished deburring and dimpling the fuel tank ribs. Deburred the skin.

September 8, 2001 - 4 hours
Finished deburring and dimpling all the tank parts. Modified my leading edge craddle, and built a little 10:1 balance for measuring pro-seal.

Little homemade 10:1 balance that I made from extra stiffener material. The bolt on the right is the balance adjustment. If I were to build it again I would make it a little larger.

September 9, 2001 - 4.5 hours
Pro-Seal session #1. Riveted/sealed the tank stiffeners, the fuel filler cap and the tank drain flange. I also sealed the reinforcement ring that goes inside the inboard rib with the platenuts. (What a mess!)

First session of the fuel tank Pro-sealing nightmare.

September 14, 2001 - 1.5 hours
Rebuilt the leading edge craddle and did some last minute preparation for the Pro-seal nightmare that is to begin tomorrow.

I rebuilt the leading edge craddle because the last one didn't work well. There was not enough room to get clecoes in and out of the forward-most holes. This one works much better.

September 14, 2001 - 7 hours
Pro-sealed all of the ribs into place in the fuel tank. Surely 1 hour per rib is a little much but that stuff was curing pretty fast and I had to mix up a batch for each rib. It's still hot in Houston.

September 17, 2001 - 0.75 hours
Installed and wired up the capacative fuel senders in the left tank.

September 19, 2001 - 1 hours
Installed the fuel vent and fuel pickup tubes and fittings as well as the little BNC connector for the fuel sender. Drilled, countersunk or dimpled the holes for the platenuts on the T-423 attach plate.

Inboard bay of the left fuel tank. This tank has the inverted fuel tank modifications.

Capacative fuel sender plate. Notice the purple masking tape, this keeps the Pro-seal away from where the baffle will have to seal.

Outboard bay of the left fuel tank.

September 23, 2001 - 5 hours
Finished closing the left fuel tank. Maybe I'll have time to forget how much I hate Pro-seal before I get to the right tank. Cleaned up the shop getting ready to go back to work on the wing.

Modification that I made to the cheapest rivet puller that I could find. This is to allow me to get into those Z-brackets that attach the tank to the spar.

Finished fuel tank. I haven't pressure tested it yet.

October 13, 2001 - 1 hours
Pressure tested the fuel tank and fixed the big 'ol leak that I found.

Pressure testing the tank. The top tube goes over the the homemade manometer and the bottom is the tube I used to 'pressurize' the tank.

Here is a picture of my homemade manometer. It is really high tech. Here is a note on how I built it.

October 16, 2001 - 1 hours
Finished leak testing the fuel tank. Decided that the leak was where my test fitting connected to the tank. Couldn't make a single 'Snoop' bubble anywhere else. Installed the tank on the wing.

October 29, 2001 - 2 hours
Fabricated the right tank attach brackets and drilled them to match the main spar.

October 30, 2001 - 2.5 hours
Finished the right tank attach brackets and bolted them to the spar. Cut out and deburred the tank stiffeners.

October 31, 2001 - 1.5 hours
Drilled the stiffeners to the right fuel tank skin and started getting the baffle lined up on the tank attach brackets.

November 1, 2001 - 2 hours
Drilled baffle to the attach brackets, drilled the skin to the ribs and the baffle.

November 2, 2001 - 1.5 hours
Prepared the capacitive fuel sender plates and drilled them to the proper ribs.

November 3, 2001 - 3 hours
Fabricated the tank attach angle (difficult with the bandsaw out of commission) Drilled the attach angle and doubler plates to the ribs. Drilled the fuel filler and drain to the skin.

November 4, 2001 - 3 hours
Cut the big hole in the inboard rib, fit and drilled the tank access reinforcement plate. Prepared the tank access plate for the fuel pickup and fabricated the anti-rotation bracket and drilled it to the tank attach plate.

November 5, 2001 - 2 hours
Fabricated the fuel pickup tube. Also made the little cover to fit over the tooling hole in the outboard rib. Started deburring and dimpling all the parts of the right tank.

Fuel pickup tube for the right fuel tank. (OOpps it is shown inside out in this picture. But don't worry nothing is tight.)

November 6, 2001 - 1.75 hours
Deburring and dimpling right fuel tank parts.

November 10, 2001 - 3 hours
Finished dimpling and deburring all of the right tank parts. Now I am ready for the Pro-seal.

November 11, 2001 - 7 hours
Sealed and back riveted all the right tank stiffeners, fuel tank filler, drain flange and six of the seven ribs. It goes faster the second time and it helps that it wasn't so hot this time so the Pro Seal cures slower.

November 13, 2001 - 1.5 hours
Installed the capacative senders in the right tank. Also cut and flared the the vent line. These things are much easier with the inboard rib off.

November 17, 2001 - 3 hours
Finished the capacative fuel sender installation, installed the inboard rib with the reinforcing ring and installed both of the reinforcement plates and the attach angle to the leading edges.

November 18, 2001 - 3.5 hours
Installed the baffle in the right tank. TANKS ARE FINISHED!!!! Now if it will just not leak then I can be done with Pro-seal.

November 25, 2001 - 0.75 hours
Pressure tested the right fuel tank, and cleaned up the shop a bit.

June 12, 2005 - 1.5 hours
Put the nutplates on the tanks where the fuselage fairing connects.

Nutplates on the inboard edge of the tank skin for the fuselage / wing fairing.

June 25, 2005 - 1.2 hours
I decided that I didn't like the cork gaskets, so I took the access covers off and pro-sealed them in place instead.

I hope that I never need to get into these tanks because I've sealed 'em up good.

July 2, 2005 - 2 hours
I tested the fuel tanks and found a couple of leaks. The leaks weren't associated with the covers that I just re-did either. That doesn't give me a warm fuzzy feeling. I found one tiny leak in each tank so I did the ProSeal thinned with MEK trick, and pulled a small vacuum on the tanks and let this stuff wick into to the leak for a couple of hours and then put some unthinned ProSeal around that just for good measure.

Disclaimer:
This web site and the infomation contained within it are for entertainment purposes only. The opinions expressed on construction techniques are my opinions only and should not be confused with proper construction techniques. There is undoubtedly more than one way to build an airplane and some methods that I use may or may not work in any given circumstance. If there is any question please call the kit manufacturer. I love to help but I am not responsible for the misuse of any information contained on this web site.

 February 3, 2021
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