Finished with the right wing, again. And starting on the left

So Spork is at the beach having fun while I’m here slaving away. Since I’d finished the right wing covering, I texted SWMBO to tell him I’d gotten it done. That way he’d know he didn’t have it waiting on him when he got back and to also let him know I was busy working while he was having fun. It was also to brag a little bit that I’d gotten everything done. The immediate reply?

Did you get the fuel tank installed?

Well, no. I’d gone to the house and had dinner instead. So much for bragging.

To install the fuel tank involves a bit of scary work. The tank slips inside a spot made just for it easy enough. But then you have to drill through the end rib of the airplane with three different holes. These holes are somewhat blind as the bottom side of the tank, where two of the holes are to be located, isn’t really accessible. And each hole has to line up perfectly with the corresponding place on the tank where different fittings are screwed in. The instructions, such as helpful instructions are, said “Measure and drill holes. Install fittings.” Um, ok. Thanks for the detailed explanation. Heck, it didn’t even say which fittings to install. Luckily I already knew but I verified with Robby just to make sure.

Before I could drill these holes for the fittings, I had to make sure the tank was installed and wouldn’t move. No sense making the holes align perfectly, only to find the tank had slipped while I was working. Scott had already coached me that rivnuts would be a better solution than rivets and had ordered some in for me to try. I’d never installed a rivnut but it seemed simple enough. Drill a hole, insert a rivnut, squeeze it with Scott’s special tool I had to borrow, then wash, rinse, repeat 15 more times.

Rivnut installed in fuel tank compression tube
Rivnut installed in fuel tank compression tube
Bag for the rivnuts, with part number from Aircraft Spruce
Bag for the rivnuts, with part number from Aircraft Spruce

After working with rivnuts for about 5 minutes, I decided they were the best thing ever. Very simple to install, and now the tank is held down by 8-32 screws instead of rivets that would have to be drilled out to remove the tank.

Tank with rivnuts installed, view through end rib
Tank with rivnuts installed, view through end rib

Here you can see the rivnuts holding the tank in place. This made it very easy to align the tank, and to install and remove it as I worked with the various fittings, tapping, cleaning out chips, etc. Definitely the way to go.

Top view of tank with rivnuts holding it in place
Top view of tank with rivnuts holding it in place

The plans only called for two rivets per side on the tank. I installed four rivnuts per side instead. I don’t think it will be going anywhere.

Now it was time to drill the holes in the end rib. Since I can measure three times and get six different measurements, I wasn’t too keen on measuring to match up these drilled holes as the plans suggest. Instead I grabbed a really small drill bit and guessed about where to drill. I closed my eyes and drilled the first hole through the rib. When I peeked through the hole in the rib, I was about 1/8″ off. Pull back, drill the hole in the new spot. Perfect! With the hole in the rib in the right spot, I simply pressed forward and pecked the boss in the fuel tank making a little dimple to mark where the fitting will be drilled and tapped once the tank is pulled.

I then swapped to a step drill and drilled out the final hole in the rib. In enlarging the hole, I took out the original wrong drill hole so no problem there as my mistake hole ended up on the ground as just some more chips.

Lower sight gauge fitting installed in right fuel tank
Lower sight gauge fitting installed in right fuel tank. It is the brass hose barn thingy towards the back of the wing. 

I did the process times three. Two holes for the sight gauges, and one for the fuel pickup line.

I then pulled the fuel tank and drilled out the holes I’d marked to the correct size for a 1/8-27 NPT fitting, then tapped them. Then it was a simple process of flushing all the chips out of the tank and then putting the tank back in place.

Right fuel tank, fully installed with all fittings
Right fuel tank, fully installed with all fittings

Here the sight gauges are in place, as well as the fuel pickup. The front port was plugged, per the manual since I’m using a Rotax engine. I guess a Lycoming must have a fuel return line that would go there.

Right wing covered, left wing ready to start work
Right wing covered, left wing ready to start work

With the fuel tank installed, I moved the right wing up against the wall as close as I could, and then covered it in a tarp to protect it from dirt and the fabric from sunlight. I then dragged the left wing over to the center of the bay and say down on a chair and stared at it a while. We’d spent weeks on the right wing. Would it take weeks to work on the left wing as well? Hopefully we’d be faster now that everything was basically the same.

I started by removing the left wing slats from when we’d mated the wings to the fuselage. That took a bit of doing as a bolt had jammed behind some sheet metal and damaged the sheet metal. There was nothing to do but to cut it out and move forward, which is what I did. It isn’t a critical area and it will be behind the slats so not really visible. With the slats removed, I could either start prepping for covering, or I could work on the fuel tank. Since I had all the parts laying right there, I decided to work on the fuel tank. It took about 2.5 days to get the compression tubes installed and shimmed, the tank installed, the fittings installed, etc on the right wing. Plus I had Spork and Cody here to help me. Now I was by myself. I flipped the wing over, started on the compression tubes, and before I knew it was at this point.

Left wing tank fully installed
Left wing tank fully installed

It took me about four hours from drag the wing out to done. 1/2 day vs 2.5 days, and that 2.5 doesn’t include the trips to the airport to ask Scott questions or borrow tools, or texts to Robby, or trips to the store. That 2.5 days actually took about a week. Yeah, maybe this wing will go a bit faster.

So this is where we are today. I can only cover one side of the wing. The magnetometer from GRT was DOA when it arrived so I need a new one before I can close the wing up. I lost most of last week because GRT shut down for Oshkosh. Today is Tuesday and I don’t have high hopes I’ll get a call back today from GRT despite my email and phone messages asking for help. (Can you tell I’m getting pissed?) Today I’m doing some farming stuff, then working on the plane this afternoon. I have some new zip ties coming from Amazon today which I want to use to secure all the runs in the fuselage instead of the plain plastic ties I used already. So when they show, I’ll cut off the old and install the new. Once that is done, I have the choice of starting to cover the fuselage, or starting to work on the panel. I’ll be stopping by Hudson’s today to grab some lexan to start on the panel anyway and panel work is a lot of head scratching so I’m leaning towards that. Once GRT calls me, I’m going to get them to quick ship the parts I need and then hopefully I’ll have the boys here to start working on covering the wing.

Once the left wing is covered, we can start on the paint booth and covering the fuselage. Then it is on to painting. After painting, the gear goes on and it is time to make airplane noises. Vroom vroom!

Leave a Reply