Dave’s RV-7A Building Log

I took advantage of the sunny weather and painted a bunch of parts for the cockpit.

Later I decided to work on the fuel vents. I figured it would be best to learn on this tubing before playing with the fuel supply tubing, especially since the 1/4″ tubing is much easier to bend.

I uncoiled the 1/4″ tubing and started working on the right fuel vent. The vent is snaked up through the cabin in order to get enough height to keep fuel from seeping out and I think to keep water from coming in. I got the basic form of the tubing worked out. The only tricky part was getting the flare on the forward end of the tube along with the tight bends needed to avoid the rudder pedals. I did the flare and then bent the tubing with the spring bender. The spring works really well to keep the tubing from collapsing while bending. It’s just a little difficult to slide it over the 90 degree bends.

I started to work on the fuel vents. The hardest part was drilling the hole for the fuel vent in the side skin. I can understand why Vans doesn’t pre-punch the hole. They use the same side skin for the RV-7 and RV-9, which have the vent in different places. But why can’t they call out dimensions on the drawings? Using the 1/8 scale on the plans, I calculated that the hole was 1.12 inches in front of the rivet line for the F-902 and 1.84 inches above the rivet line for the lower longeron. I eyeballed these measurements against the wing root, and it seems like they’ll work out ok. After much measuring and double-checking, I drilled the holes out to 7/16″ per the plans.

I also prepped the spacers needed for the fittings that will go through the skins along with some other parts. I’ll paint them tomorrow.

Adele had a soccer game tonight, so I didn’t get too much done. I shortened the bushings on the fuel selector a little bit. They ended up being 22/32″ long, which looks about right. I also grinded off the pointer on the handle. The handle itself becomes the pointer. It would be very easy to make a nicer handle for the fuel selector.

The ELT and static ports I ordered from SafeAir arrived. Installing the ELT looks pretty straight forward. I just need to find a place to put it. I’m thinking underneath the baggage floor as Dan and others have done.

I previously ordered static ports from Cleaveland, but didn’t like the barbed fittings for the tubing. A few people have lately reported that the tubing splits when forced over those barbs. SafeAir makes a slick static port system, but it costs $80. Instead I ordered their static ports for $25. By buying a couple of Nylo-seal fittings from Aircraft Spruce, I should be able to make use of most of the Vans static kit I already purchased with the SafeAir static ports.

I installed the fuel vents in the floor of the forward fuselage. I contemplated starting the fuel vent runs, but decided to do something easier.

I pulled out the parts for the fuel selector and started assembling them. A few builders have mentioned on their sites that the bushings detailed in the plans are not long enough, so I made mine 1/8″ longer. That may have been too long. I’m not sure if the fuel selector itself needs to rest against the plate. I’ll probably shorten them 1/16″. I also moved the plug and installed the fittings as detailed in the plans with some Loctite thread sealant. I installed a T in the bottom of the selector, since it’s needed for the fuel pump/filter.

I noticed that Walter Tondu powder coated his steps. I decided to try that as well. Express Finishing in Redmond did a terrific job with it. I picked a color they shoot often, matte black, and was able to get the steps back in one day. I think they usually handle much larger jobs, but they didn’t mind including my parts with another customer’s batch. Both parts cost $30. Seems reasonable to me for a coating that should be very tough. And they look great.

I ordered a better tube bender today. I’m going to wait until it arrives before tackling the fuel pump again.

I looked around for something simple to do. I decided to make the fuel vent fittings. They are basically modified fittings. I used the Scotch-brite wheel to remove the threads, cut off the end at an angle with the band saw, cleaned up the cut on the belt sander, and then did a final polish with the Scotch-brite wheel. I picked up some faucet aerators with screens at the Home Depot a few days ago. I was able to use just one screen to cover both openings. I cut the screen to shape with scissors and then used JB Weld to attach them after cleaning everything with MEK. They turned out pretty nice.

I riveted platenuts on all of the various covers for the fuel pump. There are about a dozen of them.

The next step was to fit the filter and pump to the base. As others have pointed out, one fitting on the pump needs to be turned in order to not interfere with the filter. That part wasn’t difficult, but I spent an hour wrangling with the tubing to get it to fit after moving the fitting. And it still wasn’t successful. I ended up crimping the tubing, so I’ll have to start over with a new piece. Frustrating.

I tried using the tubing bender. It works pretty good, but I can’t seem to get a nice smooth 180 degree bend. My bender only does 90 degrees and can’t seem to do two 90 degree bends right next to each other. Time to do some research on the net about tube bending.

Another weird thing is that after removing that tube, I noticed that one of the fittings on the pump was really loose. It’s a brass fitting that connects to a plastic part with an O-ring inside. The fitting was less than hand tight. I’m sure I didn’t loosen it, because I had a wrench on it when I was removing the tubing. I tightened up the fitting by hand and gave it another quarter turn with a wrench. I don’t want fuel leaking out of this thing in the future.

Of course I had to fire up the pump. I briefly touched the leads to a 12v drill battery that I have. I only ran it for a second, as the instructions say not to run it without fuel running through it–probably for cooling. The thing makes an awesome hum, and torques quite a bit when it starts up. Impressive.

Worked more on fitting the fuel pump covers. It’s really nice (not) that all of the fuel pump covers are attached with #6 screws instead of the #8 screws that are used throughout the entire rest of the plane. I don’t have a platenut jig for #6 or the right drill bits. I ended up using a 9/64″ drill from my regular drill bits.

I basically fitted all of the covers together and drilled the required holes. I had a heck of a time getting the pump platform fitted between the floor stiffeners. It was about 1/8″ too wide. I bent the two sides of the platforum inward and was able to jam it in there.

I took everything apart, drilled holes for the platenuts, and deburred all of the holes. I also cut off the front of the fuel selector mounting plate. The forward triangle is used for manual elevator trim, but I’m using electric.

While I was at the hardware store, I picked up a stubby 1 point Phillips screwdriver. I used that to attach the servo for the electric aileron trim. That’s about all I can do on that part until I get the control column mounts installed.

Started working on fuel pump covers by modifying the existing forward cabin covers. I followed that up with lots of deburring of the covers.

I figured out a way to drill the holes in the seat rib for the electric aileron trim servo. I have a left over drill chuck from when I put a Jacobs chuck on the air drill. I put the 9/64″ drill bit in the chuck and then just hand turned it. Since the holes were already drilled to #30, it wasn’t hard to enlarge the hole a little bit. After deburring, I started to attach the servo but couldn’t find my small Phillips screwdriver.

I messed around with a few other things in the cabin, but spent most of the evening on house projects.