Follow my Journey of building a Vans RV-8 Aircraft
I forgot to mention in tonight’s post that I have had 100LL fuel in my wing tanks for 2 weeks and I am incredibly happy to announce that they are 100% leak free!!! I had the tanks in all positions over this time but mostly in the vertical position so that the rear baffles, the biggest problem area, had the most exposure to the leak testing. What a great feeling to be able to say “leak free”!
Time: 1 Hour
I had a long day at work and office time so I didn’t get much work done I the hangar tonight. What I did do was create two extensions for the tank vent lines with some parts I received from Aircraft Spruce so that I could control any venting.
I then removed 10 gallons of fuel from the right tank and put it in the left tank. With both tanks half fuel I put both if them on end to test the rear baffles for leaks. So far on the right tank after 3 days I had no leaks!
I will let these sit for a couple days to check for leaks then lay the tanks on their tops so the bottom skins are up so I can test the top skin rivets. That’s all I did tonight and will get to the left wing ribs tomorrow.
Time: 3 Hours
I had planned to start the leak testing yesterday but got a late start on that task in the afternoon when I found a big flaw in my plans. I started by attaching the sump drains after getting some FuelLune from a fellow builder, thanks Glen!
When I finally got those installed I ran out to the airport where we keep our Lear 45 to grab 20gal of 100LL to do the testing. I was real excited to get this under way and ran home to fill one tank. Simple enough right! I set up the fuel can higher than the wing, placed the siphon hose in the can/wing and pumped away. So what could be wrong you ask? Well I make some dumb mistakes sometime, and this was one of them. If you remember that I placed the flop tube and fuel vent lines on the inboard rib. Well I forgot to get any caps to cover those open fittings to keep the fuel in the tanks! So after a gallon or so I started to hear fuel dripping! I was glad to see it was the fuel lines and not a bad rivet. So I stopped the fueling and got on the laptop and ordered 4 caps and some other supplies I needed. What a bonehead move on my part! Oh well live and learn! After breakfast today my fellow builder Glen bailed me out again with a -6 cap that I could use for the flop tube line and he said to use a plastic hose and clamp for the -4 vent line.
I used my safety wire and pliers to secure the hose to the fitting and folded the hose 3 times with a clamp to close the open end. With the lines now securely closed I commenced filling again.
I only have two 5 gallon fuel cans so I had to run back out to the airport to get the last 10 gallons. When I got home I emptied those into the tank to make the 20 gallons. After I got all 20 gallons in the tank I found that the hose I had used in the vent line wouldn’t seal tightly to the vent elbow so it was leaking just a little. To prevent this I had to lay the tank flat and remove the clamp from the hose so that the fuel coming from the vent could drain and would have any pressure causing it to leak at the tube/elbow joint.
So I will let it sit in this position for a few days then flip it over for the same. Hopefully no leaks, all fingers and toes crossed!
Time: 8 Hours
Today was the big day to finish up the tanks! After sleeping on it last night and going over all items in the interior I decided that all was done and all I needed to do was seal it up. The plans call for you to place a <3/16th inch bead of ProSeal just forward of the rivet holes so that when you side the baffle in it will act like a squeegee and form a filet. You also need place a bead along the outboard/inboard rib. A common leak point is at the four corners of the baffle so a good size blob goes there. I then spread a small amount around each of the rib rear flange.
After slipping the baffle into place I placed a clecko in every hole to help form the filet.
The first rivets are blind rivets at the top and bottom of the 5 middle ribs. I dipped each rivet in ProSeal before setting them to get a good seal.
Next was to attach the z-brackets with blind rivets. The process was the same and I dipped in ProSeal as well.
Next was to attach the 2 end z-brackets. For these I had to use the rivet guy and a bucking bar as the squeezer would fit on the bracket. There are 4 rivets, 2 on each side of these brackets and I was able to squeeze those.
The next task is to rivet all the skin to baffle holes. These I could grab with the pneumatic squeezer pretty easy. The real problem I had was that I found that the countersinks I had done on all these hole wasn’t deep enough! I know that I tested these holes with a rivet way back when I did them but when I set a few rivets they were sitting proud a hair. So I grabbed the countersink cage and set the correct depth and finished them. I removed a clecko, countersunk the hole and then squeezed all the way down the line. So I repeated this for both sides on both tanks which probably doubled the time I spent on them, bummer. Good news is that after that they all turned out great!
Here is a view to the inside so you can see the filet that is made by slipping the baffle in place.
So I did a little bit of touch up in those filets but for the most part they all looked good from what I could see. To finish up that sealing I needed to screw the 5 access plates on. I just buttered up the lip of the plates for the area that the cover up on the rib/baffle. They then got placed in their respective spots and I placed a ProSeal dipped screw in each hole. For the inboard ribs I used a cap head screw that uses an allen wrench so that it will be easier to access when the wings are on the fuselage. The others I just used Phillips head screws to attach them.
I then cleaned up all the surfaces to remove all the extra ProSeal I got everywhere.
I grabbed the fuel caps and placed them in their spots as well.
The only thing I couldn’t get done was to attach the fuel drains since I didn’t have a fuel lube for the threads. My friend Glen has some and I will get some tomorrow. For now the tanks will cure in my office with the space heater turned up to 80°! That means next weekend I can grab some 100LL and fill them up for leak testing. So here is my chant, NO LEAKS, NO LEAKS & NO LEAKS!!!
Time: 6 Hours
Today started with the weekend breakfast with the fellow builders and a little hangar talk. I always enjoy these days as I can run my weekly work and questions by the guys to see how my progress is coming. One other thing I wanted to do this morning was to drive to Monee, IL which is south of Chicago to an airpark called MeadowCreek (2IL9) and have a look. This is a beautiful airpark where you can build, or buy, a home with a built in hangar and live with your plane. It’s a gated community and the roads/runway are private. All the roads are also taxiways, so cars give way to any aircraft. You can wake up and open the garage door and just go fly, a complete dream for me! I had the opportunity to meet a resident there and learn that she is a realtor/pilot. It was a great little trip and will be something that I look at for the future. When I got home I was pumped up to get into the Hangar and start working. First up was to finish up all the interior tank items that need taken care if before you can finally seal up the tanks with the rear baffles. I started with finishing the wiring for the fuel capacitor plates. The outboard wire was already in place but I needed to fish the inboard wire through the bushing that has the vent line in it. This was a tight fit and took a little time to get done. Once there I made some measurements and cut them to the correct length. I then crimped the ring terminals on each of them and checked their security.
It’s pretty tight in this bay to attach these wires to the plate since they are cut to the right length. I left a little extra length and will rotate the bushings in turn wrapping the wires around the vent line taking up the slack.
With the wires all connected I grabbed the screws and the required hardware to attach the plates. Remember that these plates must be deprecate from the fuel tank structure as far as the metal is concerned. So you must isolate them with plastic pieces. The screw is placed in a tube and the tube is placed in 4 plastic washers. This isolates the screw and plate from touching the rib that it’s attached to.
Before I did the final attaching I tested the continuity of the plates with my Ohms meter. I placed the tips one each plate and got a tone. I then placed one on a plate and the other on the tank structure with no tone. Touch two placed of the structure gets a tone. I also hit the center of the BNC connector and the plates with a tone. This all proves that there is no contact with the plates and the tank structure. Once that test was done I mixed up a little ProSeal and covered the terminals to seal them up followed by attaching them to the ribs.
The slack was then removed from the wires and I added a blob of ProSeal about every 2 inches to secure the wire to the vent line.
I then attached the corner anti-hangup guides for the flop tubes with a couple of LP4-3 pop rivets.
The last item in the interior was to bend up the tip of the fuel bent so that it is at the highest point of the tank. The vent will replace the fuel with air as it’s used, but it also allows the fuel to escape overboard as the fuel expands in the heat. With out this vent your tank would crush in as fuel is used and pop as the fuel heated up.
Those were all the remaining items inside the tanks so I grabbed the MEK and cleaned all the parts that would get sealed with the baffles. In prep for the baffles and the z-brackets that go on them I marked the proper orientation of the brackets on the skin. Putting them on in the wrong configuration would really suck. So I drew the correct orientation on the skin for quick reference.
Those brackets get pop riveted and if you remembered in an earlier post when starting the tanks I moved the rivet holes on the bracket flange to make it easier to pop rivet. Even with that adjustment it is still tight so you have to grind the face off a cheap rivet puller to get to them.
So I decided to stop there so that if I forgot any item that needed taken care of I will remember it in the middle of the night! So tomorrow will be the big day and finish the tanks. That will give them a full week to cure and I will grab some 100LL to fill and leak test them.