Author Archives: Michael

Time: 2 Hours

I spent most of the day working on my sons car. It needed new rotors, brakes and calipers for it to be safe for him to drive. I’m not much of an auto mechanic so it was a big job for me. So that took up most of the day but I was still able to get so work done on the RV after I scrubbed the Hangar clean from all the brake work. So you learn early that you put parts together and take them apart and put them back together. I had to take the tanks all apart so that I can do more work on the ribs.

The next step is to work on the fuel quantity sending parts. You have 2 options to chose from, the first is a float system that uses a plastic float that rises and lowers with the level of fuel. The float system is proven but also has moving parts and has the potential for failure. The second is a capacitive fuel sender. There are a couple of benefits to this design, no moving parts and very it’s sensitive to the amount of fuel and can read the quantity very accurately. I chose to go with the capacitive senders for the accuracy that if provides. The design is based off of two individual plates in the tank that have a small electrical current and are separated by a dielectric(insulator) in this case the fuel. The capacitance between these plates and the fuel is measured giving a fuel level. The first steps is to position the 2 plates per tank on their ribs per the plans.

I then matched drilled the 3 holes with a #20 bit on one rib. I then used that rib as a guide for the opposite end rib of the other tank.  That rib was then used as a guide for the second rib on the first tank and finally it was used for the final rib of the second rib, clear as mud?  The fact that the ribs are the same part number in both tanks allowed for me to place the ribs back to back and match up the tooling holes.  These parts are pretty accurate so using the match drilling this way made the holes come out perfectly.

The plates are mounted on opposite sides of their ribs when viewed form
Inboard to outboard. So I laid them out as they would sit on the ribs so that I could mark them for the nutplates that they get.

I then treated all the edges and debured the holes so that I could rivet the nutplates. That was a pretty quick process with the squeezer. I decided to call it a night and clean up but before I did I mocked up one plate to see how it looked. The plates need to be isolated from all other metal, the rib, and have plastic spacers that take care of this.

I will get back at it tomorrow and make more progress on the tanks.

Time: 5 Hours

Today I created a mirror of the bracket I made yesterday. I used a combination of the bandsaw, table disk sander and the good old scotch-brite wheel to get the shape just right.

The plans are a little vague about the next step which is to match drill the bracket to the rib as well as the reinforcing plate on the opposite side. The plans just call for the bracket to be 2″ from the leading edge and shows a pattern for the rivets but no dimensions. After talking to my friend (Glen a fellow -8 builder) I made a plan of attack. First I lined the bracket up to be parallel with the rib stiffening bend at 2″. Then I just eyeballed the placement of the rivet layout. Since I’m going with flop tubes in both tanks I needed to account for them with this layout. That’s due to the fuel line elbow will now come through these parts rather than the access plate at the aft end of the rib.

As you can see I used the nut to make sure I had clearance from the rivets.

Once I was happy with the layout I drilled the holes to their final size, the very center hole will be enlarged to 9/16″ for the fuel line elbow. With that done I could now use the bracket as a guide to drill the rib and backing plate.

I used my step bit in the drill press to enlarge the hole for the elbow.

I still need to enlarge the hole in the opposite bracket but was getting tired and will get to it tomorrow. It was a good day in the Hangar even though it was only little things that got done.

Time: 5 Hours

Today I finished up the countersinking of the skin to baffle attach points on the left fuel tank. I also finished up enlarging all the holes for the perimeter screws to the required #19 size. I didn’t take any photos of that stuff since I did a bunch for the right tank and they looked exactly the same. There are two brackets that are attach points for the inboard forward portion of the fuel tanks. These have to me fabricated from 2″x2.5″ aluminum angle. The plans give you dimensions and you have to do the designing.

Once I got the shape pretty close I test fit it to the rib.

After I was satisfied with the fit I transferred the shape to the other blank angle.

I will get that cut and shaped tomorrow as it is getting late and my back was getting a little sore.

Time: 1 Hour

I got home tonight and decided that I need to make some daily progress, even if it’s only 1 hour. So I fired up the heater in the Hangar and went out to do some work. I finished up the right tank countersinks, I just had the top of the skin to do. This is a slow process even though the cage was already setup for the proper depth since I really take my time with them to ensure they come out just right. Once that was done I hit all the spar attachment holes with a #19 drill bit to get them ready for the #8 dimple die. This will make the dimple for the AN509-8R8 screws that will help hold the tank on the spar/wing. I will eventually use stainless steal screws here and not paint them. Once those screws get painted and you have to remove the tank for whatever reason they never look the same so I’m going unpainted with mine. That was enough work for tonight and should get some good time in the Hangar this week as I have a light flight schedule.

Time: 6 Hours

Today started with riveting the K1000-3 nutplates on the z brackets. There are three per bracket and 12 brackets that need them. I set up the squeezer and went at it. It didn’t take too long once I had the setup all done.

You can see one bracket is missing a nutplate! I ran short since I used 4 of them when I was drilling the brackets and used the nutplate as a jig. The drilling process started enlarging the holes of the nutplate after a a couple of brackets so I had to use several. I also used 2 extra when riveting them to the main spars and had to drill out a rivet causing damage to those nutplates. I placed an order with Aircraft Spruce for some more and will finish when they arrive. Next up was to match drill the tank skins to the ribs and baffle. I set up the drill with my #40 reamer and hit every hole, and there are a bunch! On each of the ribs there is on hole that needs to be drilled using the skin as a guide so I did that as well.

After those holes are drilled I opened up the lower half of the tank to get access to where the stiffeners go. I clecko’d those and reamed them as well.

I then removed the stiffeners and closed up the skin and repeated everything on the other tank. The plans call for countersinking all the holes that run spanwise and connect the tank skin to the baffle. This is done rather than dimple so that the installation of the baffle, durning tank sealing, is easier as it would just slide in and not fight with the dimples. The skin is only .032″ thick and the thinnest that you can do countersinking on. You do the countersinking with the skin clecko’d to the baffle so that the holes in the baffle will act as a guide for the pilot on the countersink bit. After removing a strip of the blue film, I set up the bit/cage for the right depth and started on the lower side of the right tank skin.

I was a little nervous about countersinking the skin but it went well and I had no problems on the lower skin. My shoulder was a little tired from all the drilling and decided that this was a good time to call it a day and watch some football. So next time in the Hangar I will finishing the countersinking on the right tank and both sides of the left tank.