Today I riveted the right wing gap seals. This went quite well.
After clarifying with Vans their recommendation to use pop rivets for the flap gap seal, I started by cleaning the rear spar area, which is the “top” of the wing when sitting in the stand. A lot of dust, pollen, and shavings had gathered, so I took the time to blow it off with air then wipe it down with a damp cloth.
The I clecoed up the gap seals and started riveting. I squeezed all the rivets except those behind the already-installed bottom skin. For those I followed Van’s guidance and used Cherrymax and MSP-42 rivets. This was my first experience with Cherrymax, and I was surprised at how nicely they set. The countersunk rivet heads came. Out looking nice, and the squeezed manufactured heads looked good too. The only annoying thing was having the stems not breaking cleanly on a couple of the 42’s. I ended up filing them down which was time consuming.
I squeezed most of the rivets; all of the rivets on the skin and all of the aileron gap seal rivets (with one exception). Everything else got pulled rivets.Close up of the Cherrymax rivets. They are very nice to use and the finish is excellentInstalled
Today I finished installing the access panel, installed an adel clamp for the pitot lines, and riveted on the end caps for the gap seals.
The access panel was straightforward; I riveted on the nutplates, then riveted it to the wing. I then spent time getting the panel itself to fit, I had to file about 1/32 off one edge. Then I screwed it on. I ran into a problem when the last screw’s head sheered off. I need to pick up an easy-out to remove this and try again. It sure why it sheered off, I don’t think I was using too much torque, just a handheld screw driver.
Riveting nutplates to the doubler plateRiveting the doubler plate to the wingDoubler in position.Adel clamp holding the AOA and pitot lines. This is secured using one of the tank attach bolts.Riveting the ends onto the gap sealsFinished gap seal end
I took another pass through the plans looking for any jobs I missed on the wings, before I start closing them up. I came across the access panel in the forward skin of the left wing. This is to allow access to the stall warning system, (which I’m not planning to install). I have been thinking that this would be a great location for a camera. I’d like to have a camera that can see in front of the airplane, as there are some blind spots when taxing, and during takeoff and landing. Anyway, that can wait, for now I just need to install the access panel itself.
I deburred and dimpled the doubler plate and the access panel, then primed the doubler plate. Then I deburred and dimpled the rivet holes in the bottom skin. Once the primer is dry I can finish the job by attaching nutplates to the doubler, and then riveting the doubler to the wing.
Doubler and access panel (the panel is in the background and appears smaller than it really is)
Tonight I countersunk a fee holes on the rear wing spars, where the gap seals will flush rivet to the rear spar. it’s about 16 holes in total I think, so not a big job. What took more time was sorting through my countersink cages, swapping out the #30 countersink for a single-fluted bit, and then getting it configured to countersink to the correct depth on some scrap. The single flute is so much nicer than the more common three-fluted bits. It makes a very nice cut and just polishes the hole. It seems to be much easier to avoid chatter or deformation that can sometimes occur with the three-fluted bits.
After countersinking, I primed the holes and touched up the primer on a few other spots on the spar.
Countersinks on the rear sparTouched up the primer with a q-tip
I didn’t take any pictures, but tonight I primed the gap seals for both wings. I used my standard primer the Stuart Systems EcoPoxy water-based epoxy primer. I am using high air pressure, lots of air, and minimal paint flow. It means I’m slowly building up layers, which makes for a better finish, I think. The downsides are that I’m often waiting for the compressor to catch up, so it’s slow, and paint particles get blown all over the garage. I have a fine layer of primer on many things in the garage. The high airflow seems to also dry the paint very quickly. So most of the paint particles being blown around are dry by the time they settle on things, and it’s more of a dust than a layer of paint.
Today I dimpled the gap fairings for both wings. The plans are not very detailed, but some common sense seems to be in order, I think I have dimpled the correct sides of the parts.
I also found a couple of steps of didn’t realize I needed to complete. I short row of countersinks in the wings, and the j-channel for the outboard bottom wing skins. The j-channel isn’t drilled, and is supposed to be match drilled using the spar. I’ll need to match drill it against the skin, which should be ok, but would have been easier before I dimpled it.
Gap seals dimpledClose up of the dimple orientation
Two days ago I set up a tank test on the right wing tank. This time I carefully checked the tank fittings to ensure I had the correct amount of torque. I pumped a little pressure into the tank and left it for a couple of days. The water level in the manometer has tracked the temperature changes very closely, and I’m sure the tank is not leaking.
Tonight I primed the bottom skins for both wings. I have other parts ready to prime too, but I’m out of bench space, so will save that for tomorrow. It’s easy when only priming gone side of the parts, especially when they are flat and rectangular.
Tank holding pressure. Water level rose 1.4 inches (0.7 x 2) with a 1.7 degree increase in temp. More importantly, the water level was the same the next day, at the same temp and pressure.Etching one of the bottom wing skins
The last two days I spent time making some mount brackets for extra molex connectors in the wing root. I needed to have at least some modifications to account for the pitot heater wiring (3 wires), but wanted to also mount a molex connector for the extra wiring I’ve run through the wings. This will make it much easier to install additional electrical devices in the wings later.
After checking with Vans, that I could safely rivet through the torque tube mount bracket, I cut out some small plates from a sheet of 1/16 aluminum. Then I marked the location for the molex connectors, cut them out with a drill and Dremel tool. Once I had a good fit for the molex connectors, I located them, drilled some holes, deburred, primed and riveted the plates into position. I have one connector on the right wing for the three spare wires, and two connectors on the left wing; one for the pitot tube wiring and one for the spare wiring. I used a bigger molex connector for the pitot tube wiring since this will carry 10A on two of the wires (power and ground for the heating element). The spare wiring will carry much lighter loads, as the wire is a smaller gauge.
One of the plates I’m using to mount the extra wiring molex connectorsCutting holes to size with the Dremel toolCutting holes to size with the Dremel toolRight wing test fitLeft wing plate primed and rivetedLeft wing completedRight wing completed
Today I spent some time tidying up and securing the wiring runs in the wings. This was mostly a case of installing zip ties and de-slacking the runs. I also installed some heat shrink to each of the molex connectors and installed some spiral wrap in areas where there’s a possibility of rubbing on bolts on the wing spar, or screws from inspection plates etc.
Zip ties on wiring runsHeat shrink where wiring runs terminate into molex connectors
With the pitot mast powder coated, last night I finished up the pitot tube install. Since I’m using the Gretz mount, and the wings are going to be stored for a while, I’m going to keep the mast and pitot tube uninstalled until I mount the wings. At this point I’ll just get all the fittings attached to the pitot tube, and bend the aluminum tubes to clear the aileron push tube.
Having not bent any aluminum tubing before, nor flared tube ends, I had some experimenting to do. I had the tools, but hadn’t spent time learning to use them. EAA’s hints for homebuilders has a couple of great videos on this, if you can find them. I had some scrap 1/4 inch tubing to practice with. I used some scrap to make a template of the bends I needed, which allowed me to ensure I can route the pitot and AOA tubing around the elevator pushrod that would otherwise interfere with the tubes. I was also able to confirm that I will be able to pass the pitot tube through the mast, given the bends I was making.
Template for the planned bends
The only real problem was working with the two tubes (pitot and AOA). Bending the first one was easy, the second slightly harder due to interference from the other tube and the tube bending tool. Following a slightly different line, I worked around the issue.
Mast was able to pass over the bends no problemTest fitting onto the wing. This will be fine
The next step was to trim the tubes to give plenty of clearance from the top skin. Tube cutter worked ok, but again some interference with the other tube created a small problem.
With the tubes trimmed it was time to install the sleeves and b-nut, then flare the ends of the tubes. Apart from the interference issue, this was an easy step.
Flared tube ends keep the sleeve in place and help create an air seal
Then I was able to answer a question that I had been contemplating, which was how to run the wiring between the pitot tube and the controller. There is a rib between the pitot tube location and the controller location. The connectors are bulky and I’d need to either cut them off and rewire after passing through the systems hole, or route them through the lightening holes in the rib. I found I could pop out the snap bushing and pass the connectors through the systems hole in the rib. This will allow me to use the systems hole for the wiring, as I can cut a slit in the bushing to pop it over the wires, then push into the systems hole.
