This morning I finished out chapter 41 (wing attach) by installing the fuel vent lines. I opted for Aircraft Specialty vent lines, just to save some time and effort, and I also installed the JD Air fuel vents.
The standard Vans fuel vent design has a fuel line passing from the tank down through the wing fairing, where it’s chamfered at 45 degrees. I’m sure this works great, but there are a couple of downsides. The line has no screen, so there’s a risk of insects or dirt making its way into the fuel line, or even the tank, and causing an obstruction. There’s also a chance I’ll snag the vent on something and damage it. JD Air makes a streamlined vent with a built in screen, so I installed these instead. Aircraft Specialty makes a fuel line that fits the JD Air vent, so that was very convenient.
The vent itself attaches to the bottom wing root fairing using a bulk-head fluid fitting, so it simply screws into position. I was then able to loosely install the fairing, position the fuel line, final torque the fairing screws, then torque the b-nuts on the fuel line to secure it in place.
Everything went well, the only bummer is the gap at the aft end of the fuel vent, caused by the curvature of the fairing. It’s no big deal, it’s just cosmetic, and no one will see it unless they look for it specifically.
I also installed fuel placards and some grip tape on the pilot side of the wing walk area.
After a weeks off for the holidays, I was able to make some more progress this week.
I finished the wing root fairings, and installed the wing root fuel lines. These are the lines that connect the fuel tanks in the wings to the fuselage.
The wing root fairings were fairly straight forward. Getting the right shape on the bottom fairing was probably the biggest challenge.
Soon after getting the shape right I realized that I needed to countersinking the holes on the tank attach bracket. And then I noticed I had more containing to do on the wing top skin, so that the top fairing could be installed.
I brought all my countersinking, drilling, dimpling and riveting equipment to the hangar today and knocked it out. The countersinks are a little tricky because the nut plates are already installed, so a #8 countersink (the correct size) doesn’t work because the pilot interferes with the nut plate threads. I used a #21 count sink bit which seemed to be just the right size to fit into the nut plates. The countersinks are fairly deep because the fairing has #8 dimples that need to nestle down into the countersinks. The aluminum stack up is several layers deep, so there is plenty of material to support the counting depth. The only tricky part was the top, inboard countersink on the tank attach bracket. This was too close to the fuselage to get the counting cage to sit vertical, let alone the drill. I rigged up a long extension, about 18 inches long, a drilled those countersinks without a cage. It was quite easy to see the depth and I just went little by little until it was done.
There are some holes that need to be match drilled, and then 3 nutplates installed on each size. I drilled, dimpled and riveted these.
I found some proseal and used it to glue down the wing spar spacers, after giving them a little shape to conform to the wing skin.
The fuel lines were next on the list. These were pre-bent by Aircraft Specialty, and they fit exactly right. The time consuming challenge was finding a way to get them into position. The line is short and quite inflexible, and the flared ends, which are easily damaged, mate to the aluminum fittings on each side.
I loosened up the fuselage side fitting so I could flex it inboard and create enough space to insert the fuel line. I had to use a wedge to push and hold the fuselage fuel line out of the way enough to insert the new line. Once the line was in position, I torqued everything up and it all looked good.
The three nutplates that I installed, this picture is of the right hand side, it’s a mirror image on the leftClose up of one of the nut platesCountersinks on the top of the tank attach bracket. The one at the top of the image is close to the side of the fuselage and hard to reach. The spacer glued into position on top of the wing spar. This hard plastic block supports the upper wing root fairingTop fairing installed on the left sideThe underside of the bottom fairing. The screw in this position grazes the end of the wing spar. Rather than installing a full length screw, I plan to order and install some shorter screws that will stop short of touching the sparThe fuel line in place. The wing tank is on the left, and the fuselage is on the right. B-Nuts are not torqued yet.Looking down at the left hand side fuel line After torquing the B-nutsEarly morning at Ramona after a rainy night
For some reason, Lycoming shipped the engine with an extra fitting in the fuel spider. The Vans plans warn about checking for this fitting and removing it. Unfortunately, the fitting can’t be rotated, as there is interference with the engine case. So I had to remove the spider, remove the fitting, install a plug, and reinstall the spider. This ended up being quite easy.
The fitting closest to the wrench in this picture is not used on my installation, and needs removing.Fitting removed and plug installedLooking down on the fuel spider
Tonight I wired up the Manifold Pressure, engine oil temperature, and fuel pressure sensors. I wanted to finish the job and wire up the oil pressure sensor, but I ran out of butt splices. I tested the sensors by powering up the instrument panel and looking for signals. I was happy to see all of the gauges reporting data correctly.
I also took the opportunity to test and adjust the canopy unsafe warning. At first the canopy pins weren’t contacting the micro switch, but after a quick adjustment it now works great.
Oil temperature sensor wiring Typical connection between sensor and wiring harness. I used butt splices because I don’t want these to come apart in-flight, and I have plenty of wire length to allow cutting and re-doing this if I even need to replace the sensor
Tonight I installed the cushion clamps to secure the manifold pressure line, and the rubber hoses to route pressure to the e-mags.
I found I had to make an adjustment to the routing of the line, so I removed the engine-side connector, rerouted, then reconnected the line. That also led to moving some clamps around, but I think I have a good routing now. Once the oil cooler scat tubing is installed I may have some interference, but I’ll deal with that later.
Installing the rubber tubes was kind of a pain, as access to the mags is somewhat restricted. But I get the feeling it will be even worse when I have to do some wiring back there.
Rerouted line to work around the engine mountThe rubber hoses installed Final routing on the left hand side
Tonight I installed the oil pressure sensor line, and started on another modification to move the manifold pressure sensor. This modification is courtesy of Steve at Aircraft Specialties and makes use of the unused port on the Vans bracket. It’s a more elegant solution for providing manifold pressure to the two E-mags, in my opinion.
The oil pressure line was straight forward, just connecting two fittings with a hose, and torquing the b-nuts.
The manifold pressure line was slightly more involved. First uninstalled the pressure sensor from its original location on the right side of the firewall, and reinstalled it on the left side, using the spare port. I hunted around and found a spare plug, and then installed that along with the Aircraft Specialties supplied fluid fitting. I made up the rest of the fittings, routed the lines across the engine compartment and installed the line at both ends. Now I just have to locate and install the cushion clamps to secure it in place.
Oil pressure line connected and torqued Manifold pressure line routed across the top of the engine compartment. The two needle fittings will connect to the two e-mags using lengths of rubber hoseThe lines routing to the Vans bracketTop-down view of the Vans bracket. The fitting on the right is a straight fluid fitting, despite looking like it’s 45 degrees in this picture. Sensors from left to right: oil pressure, fuel pressure, manifold pressure
Tonight I finished installed the remaining fuel lines, torquing them and marking with torque seal. With that, the fuel system is plumbed from the wing root, through the fuselage, firewall, engine-driven fuel pump, fuel transducer, fuel control, fuel spider, and out to each injector. Once the wings are installed, the final piece is the short connection from the wing root to the fuel tank.
This felt like a bit of a milestone, so I took a selfie from under the engine.
Firewall exit. After fretting about clocking this fitting to 5 degrees, I have no idea why that clocking is even necessary. Perhaps it’s related to the EXP engine changesFuel pump connection Fuel controller connection Looking up from under the engine
Tonight I installed the rubber extension tube on the breather line, zip tying it to the tab that attaches to the exhaust. This endures any oil that escapes from the breather line drips down onto the exhaust and is vaporized in flight.
