Scott & Tanya Card RV9A build log (N4822C)

I decided I’m going to learn to make my own fuel hoses.
Step 1: Figure out the routing and proper length.
Step 2: Wrap the hose with tape where the cut line is and cut very slowly and carefully with a dremel cutoff wheel.
Step 3: Cleanup any stray strands.
Step 4: Lube everything up real good with some oil. The inside of the hose, the fitting, the threads, etc. Liberally.
Step 5: Push the hose into the sleeve all the way until it bottoms out on the base of the threads.
Step 6: Mark the hose at the base of the sleeve to keep an eye on “push out” while the fitting is threaded in.
Step 7: Holding the hose in the sleeve, push and thread the fitting in.
Step 8: Tighten the fitting against the sleeve and ensure the hose wasn’t pushed out more than 1/32″.
Step 9: Pressure test to 1.5 times rated pressure.

This takes a little bit of practice but is pretty cool to be able to do. Some things that I learned along the way: Use liberal lubrication of the whole assembly. At first I wasn’t using enough oil and things got really tight really fast when trying to tighten the fitting all the way. More oil makes all the difference. I’m using Marvel Mystery Oil. It is what was handy. Also, use the cutoff wheel very slowly. If you try to cut too aggressively with the wheel, it will fray the hose just enough to make it a real pain.

I decided to put a 45 degree fitting on the mechanical fuel pump inlet so that the hose would clear the bottom of the prop governor housing on the accessory case. Others have just used a straight fitting there and allowed the hose to rest against the accessory case, but that didn’t give me any warm fuzzies. I did have to drop the bottom part of the fuel pump in order to thread the 45 deg. fitting into the pump housing. I’m much happier with the inlet setup now. All of these hoses that I’m making are Aeroquip 701 hose with straight fittings. The firesleeve that works well on the -6 fuel hose is -10 firesleeve. This is all just fabrication and mock-up right now. Later I’ll come back to all of this stuff and put clamps on the firesleeve and finalize all the fittings. Anything that doesn’t have a dot of inspection lacquer isn’t done.

I put a 45 degree steel fitting on the carburetor inlet and clocked it just so. Ahhh… entry of the dreaded fuel flow transducer. The pictures tell the story. I’ve spent a tremendous amount of time trying to figure out where/how I was going to plumb this thing. If you’re looking for a perfect, per spec, installation of the flowscan sensor, this isn’t it. But I have very reliable information on a flying example of an installation exactly like this that works just fine. Even if there is a tiny bit of error (because of that 90 degree turn on the outlet), I’m ok with that. Ok, enough of defending my installation. I tinkered with the orientation of all this for quite some time before committing to making the hoses. I’m just going to use an adel clamp to hold the flowscan in place on the engine mount. It is important that all of these hoses have some bends in them and aren’t just straight shots. This is harder than you might think sometimes. The bends are important because the engine is going to be jumping around a bit in relation to the fixed engine mount. The hose bends allow for that movement.

I painted the filtered airbox and that is drying. The carb heat on the airbox is all fabricated and ready for complete airbox assembly. A shop setup note: We’ve been thinking about how we’re going to be setting up our hangar. We decided we’re going to use some cheap plastic storage cabinets to store a bunch of stuff in. We actually found a place to put one in the garage. It now houses all of the parts trays that I’ve always used for all the small hardware. As we get further along and I buy more stuff to have on hand, the tray count has been steadily increasing. I’m so excited about this cabinet because I don’t have all this stuff stacked around the garage any more. We should have done this long ago.

 

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

 

I finished up machine countersinking the rivet holes along the sides of the cowl halves at the hinges. I drilled some additional gripping holes in between all of the rivet holes in the hinges and roughed up the surface with some 60 grit paper. I used proseal (my favorite bonding agent) to secure the hinges to the cowl. I’m letting that cure for a few days. Then I’ll go back and rivet the hinges. The idea here with gluing and then riveting is that the proseal bond will dampen some of the vibrations that would eventually loosen some of the rivets.
I also received the 30″ stainless steel primer line that I ordered from Mattituck. I’m going to use this line to go from the tee on the back of the engine to the primer valve down my the gascolator.

 

  

  

  

 

I’m still working on the lower cowl ram air inlet and airbox. I applied a couple more layers of glass around the outside of the cowl inlet to put some more “meat” on it. I also trimmed up the air filter to fit around the accelerator pump on the carburetor and put a bunch of high temp RTV on it to set. The airbox is ready for paint and final assembly (finally). The ram air inlet on the cowl needs just a bit more sanding and it will be good to go. Next up is installing the side hinges on the cowl halves.

 

  

  

  

  

  

 

Merry Christmas! I spent most of the day in the garage on Christmas eve working on forming the glass layup for the ram air inlet in the cowl. The airbox is not done yet, but is in its final shape. So I used the blue foam that Vans provides and tack glued it to the inlet inside the cowl. I used a hacksaw blade to shape it to fit inside. This is nothing more than an art project. Before I installed the cowl for exact shaping with the airbox, I did some rough cutout shaping. Then the cowl and airbox went on and I used the hacksaw blade to bring the foam into a perfect transition to the airbox. I used a small piece of sponge rubber from a seat cushion (same stuff I use during glass layups) to put a final “finish” on the foam instead of sandpaper. Then it all came back off and I did the glass layup. I tried the balloon trick as described in the instructions and that others have used. However, the glass layup was just too slippery and the balloon wanted to expand to one side or the other of the inlet restriction. When it did this, it messed up my beautifully laid glass. A big mess ensued and the balloon was abandoned. I simply relied on getting my glass layup as perfect as possible the old fashion way. It all worked out in the end. A side note here: This was Christmas eve evening, I was certain that I wanted to try the balloon trick, but none were to be had around the house. I played with a latex glove but couldn’t seem to get anywhere near the right shape out of it when blown up. Tanya volunteered to run up to the Walgreens for balloons after dinner. She did, returning with an assortment of seemingly perfect balloons. She gets the gold star for her assistance even though it didn’t work out.

This evening, I got back to the shop to check out my handiwork from yesterday (I did some more glass layups on the airbox as well). It all looked good. I was happy to find that the glass hadn’t fallen out of the air inlet while drying. I chipped out the foam and did some trimming. That is where we stand, ready for another layup for reinforcement on the inside of the inlet. I also made some revisions to my manifold pressure restrictor fitting which I noted in a previous entry.

 

  

  

  

  

  

  

 

The filtered airbox construction is kind of left as a mystery by Vans. I started by replacing the carburetor drain plug with the screw that Vans provides for clearance in the mounting plate. This whole process is just a bunch of trial and error fitting with the lower cowl. Very early in the process, the airbox has to be cut to rough length to be able to get it to fit inside the lower cowl for alignment. The top plate and mounting plate are clamped to the carb base and the lower cowl is installed. The top plate and mount are aligned with the scoop in the cowl while clamped together. Then it all comes off and some holes are match drilled. A few hours later, after fabricating the alignment brackets, it is time to do some fiberglass work. The airbox has to be adjusted to match the upward bend required to meet the scoop in the cowl.