Jan 28, 2015     Fuel vents - (1.0 hour)       Category: Fuel System

Among other things today, I fabricated the two fuel vent lines that go on the belly. I made 90-degree bends in some 6" line, then used the bandsaw to cut them at an angle that still results in good ram air flow, but keeps them relatively short.

Over the years, I've read several reports about people having fuel feed problems, tank damage, and even engine failures due to insects making their homes inside the fuel vents. There are several solutions to the problem. One is to bond a piece of fine-mesh screen over the ends of the vents with proseal. Another is to insert a folded, 3" piece of 0.040" safety wire into the vent. This is the technique I used for now. We'll see how it works in the long run. I can always change it later.

Finally, I inserted a rubber grommet in each of the vent holes in the gear cover plates. There is enough room inside the grommets for the plates to be easily removed without disturbing the vents.

  Jan 19, 2011     Fuel lines - (4.5 hours)       Category: Fuel System

I took delivery of my custom-made flexible Teflon fuel lines today, so this evening's work was to get them installed. The first thing I did was to clean the lines thoroughly with solvent and lots of high-pressure air.

An initial test-fitting indicated that there would be some rubbing on one of the gear tower holes, so I enlarged the hole a bit. Everything looked good as I installed the lines, but after tightening everything down, another slight issue cropped up with another hole, so I had to remove everything (including the fuel selector and the fuel filter) and grind a bit more clearance. The third time was the charm.

One of the flex lines ended up being pretty close to the aluminum hard-line from the fuel filter to the boost pump (see photo #2), so I zip-tied a length of protective vinyl tubing to the aluminum line. I'll keep an eye on this area after the plane is flying to make sure there's no rubbing going on.

The final pair of fuel lines have turned out to be quite a bit more of a project than I'd expected, and it's really nice to have them installed once and for all... even if I did cheat and use flexible hoses.

  Jan 13, 2011     Fuel lines - (4.0 hours) Category: Fuel System

I removed the kinked fuel return line (and the supply line I'd installed the other day) and measured for a set of custom Aeroquip Teflon hoses.

Because of the angle of the new 90-degree hose-end fitting I'll be using on the bottom of the fuel filter, I had to slightly enlarge the hole in the forward side of the gear tower.

I also messed around with the hose-end fittings. They're specifically made for Teflon hoses, and they're a little different from the aircraft hose fittings I've installed before. I cut the hose and attempted to install a straight fitting, with some success, but not enough to make me feel comfortable installing the hose yet. I'll play around with the process over the next day or two. When I make one I like, I'm going to have it pressure-tested.

  Jan 10, 2011     Fuel lines - (3.6 hours)       Category: Fuel System

Installed the rest of the fuel lines, the fuel selector, and the swivel-tee connector on the selector. And that's when I goofed. In an effort to get the final fuel line aligned precisely with the nipple on the fuel selector, I guess I applied just a bit too much downward pressure on the line where it passed through the aft side of the gear tower. I didn't notice anything out of the ordinary until after the installation was complete and I was checking everything over. The fuel line, where it passed through the bulkhead, looked like it had widened a bit -- a sure sign it had been kinked. (See photo.) A tip: Keep an eye out for this kind of damage to your aluminum fuel lines, because it's impossible to see a small kink when it's located in an area like this. You can only tell the tubing has been damaged by looking at the effect the kink makes on the width of the tube. Properly-bent tubes should be nearly uniform in diameter, regardless of the bend radius. That's what the fancy tube benders are for. If you make bends by hand (as you must sometimes), make sure they are minor ones, and not made against solid objects like bulkheads.

My plan is to remove the line and remake it, but I may have to order a bit more 3/8" tubing. I might also revert to my earlier idea of using flexible Teflon hose. We'll see.

  Jan 09, 2011     Fuel lines - (4.7 hours)       Category: Fuel System

There are a couple of projects I hadn't particularly looked forward to during the building of the airplane. Looking back on them, none of them now seems particularly menacing. I guess it will be the same with the two fuel lines I fabricated today. (These are the supply and return lines that run between the fuel selector and the electric fuel boost pump package.) These are very tricky installations, with tight quarters and very tight bends. I had originally decided I would simply avoid any potential problems by using Aeroquip flexible hose with angled racecar fittings on them. But as I began doing that today, I was struck with a strong desire to BEAT this issue and, by God, bend them out of raw 3/8" aluminum tubing -- just the way Dick VanGrunsven deigned. So I did.

It took three attempts for one of them, and two for the other, but they are now installed and looking good, if I do say so myself. (Anybody need some scrapped aluminum fuel lines? I guess they'll go on my Builder Wall of Shame.)

The only remaining job is to attach a right-angle fitting to the main fuel feed line from the bottom of the fuel selector. I'll try to find one tomorrow. If I can, the entire fuel system aft of the firewall should be complete later in the week.

Photo 2 shows the underside of the fuel selector. The return line is on top, and the supply line is on the bottom.

  Jun 15, 2009     Fuel flow transducer - (.1 hour)       Category: Fuel System

Installed the replacement hex-head socket screw on the fuel flow transducer.

  Jun 14, 2009     Fuel flow transducer - (.4 hour)       Category: Fuel System

Completed the installation of the fuel flow transducer on its custom mount (although I still have to swap out one mounting screw when it arrives later this week). I also fabricated the two fuel lines that connect the transducer. These worked out pretty well.

  Jun 13, 2009     Fuel flow transducer mount - (1.0 hour)       Category: Fuel System

After thinking about the use of #6 screws to mount the fuel flow transducer, I decided to modify the mounting angle angle to allow the transducer to be attached using an AN4-13A bolt and a long #8 screw. The larger AN4 nut required me to trim away the flange of the angle. (By the way, an AN4 bolt cannot be used on the outboard side of the mount because the longeron it attaches to is not wide enough. A 1-1/2" #8 screw with a bushing through the transducer will work fine.)

I primed and painted the mounting angle, and it'll be ready to attach tomorrow.

  Jun 12, 2009     Fuel flow transducer mount - (3.8 hours)       Category: Fuel System

While waiting for some paint to dry, I decided to tackle the fuel flow transducer mount in the forward fuselage. First, I cut some heavy-duty aluminum angle. Next, I drilled out the four holes in the angle to their final size (#30 for the outboard attach rivets, and #27 for the two holes where the unit will attach using #6 screws.)

Since the attach holes in the unit are set up for AN-3 bolts, I made some screw bushings out of aluminum spacers. These will slip into the large holes and make them perfect for the smaller hardware I'll be using.

I drilled the attach angle onto the fuselage longeron just outboard of the fuel pump. This location will keep it on the "cool" side of the firewall, and also satisfy its requirement to be in an undisturbed section of the fuel line.

  May 30, 2009     Fuel flow transducer plumbing - (1.4 hours)       Category: Fuel System

Today I fit the first of two fuel lines that will connect to the fuel flow transducer. The first one goes between the pump outlet and the transducer inlet. Since the transducer requires several inches of relatively smooth, undisturbed tubing upstream of the inlet, I had to take the line aft quite a way before making the final bend. I won't cut and flare the tubing on this end until the transducer is installed in its final location.

I also fitted the AN fittings to the transducer.

  May 28, 2009     Fuel flow transducer mount - (.5 hour) Category: Fuel System

Began examining locations for the Floscan fuel flow transducer. The best location appears to be outboard of the electric fuel pump, attached to the nearby longeron. I'll have to fabricate an attach plate for it.

  Apr 05, 2009     Fuel line - (1.9 hours)       Category: Fuel System

I'm finally getting more proficient at bending 3/8" fuel lines. I actually fabricated the right wing fuel line perfectly on the first try (which is good, because it's 53" long)! I test-fit it, but I won't install it permanently until after I install a few more items in the cockpit, and attach the wings. This fuel line is very close to the wing bolt holes, and I don't want to risk dinging the fuel lines while hammering on nearby bolts.

One more fuel line to go, and perhaps this one will be easier, now that I have the 'zen' going.

  Apr 03, 2009     Fuel lines - (2.5 hours)       Category: Fuel System

More fuel lines today. I test-fit a pre-fabricated fuel hose that I'd purchased long ago. The 90-degree fitting fit the bottom of the fuel filter and the holes in the gear tower just fine, but the hose ended up being 1" too long. I guess I mis-measured. One inch might as well be a mile, and there's no way to use it. I'll probably revert to fabricating a conventional aluminum line rather than buying an expensive, new hose.

I decided to tackle what I thought was going to be a tough job -- fabricating the fuel line from the left wing tank to the fuel selector. I thought it would be difficult because it had to make a very close-tolerance set of bends in order to clear the valve, the floor, and the Grand Rapids EIS unit that will occupy the normal fuel selector position. It turned out to be a lot easier that I thought, and I was pretty pleased with the result.

Photo 1: Pre-fab fuel hose looks great, but it won't work.
Photo 2: Grand Rapids EIS unit.
Photo 3: You can see how close the bend in the fuel line is to the EIS. It actually clears by more than 1/2". [Superseded.]

  Apr 02, 2009     RCP air vent bulkhead fitting - (1.2 hours)       Category: Fuel System

Installed a nice aftermarket bulkhead flange on the right side of the fuselage where the rear cockpit air vent line will connect. This will hopefully make the wing installation easier than I've seen with some people's airplanes. My friend Don drove the rivets while I bucked.

  Apr 02, 2009     Fuel lines - (.5 hour)       Category: Fuel System

Part 2 of 2:

Since I'm installing a piece of avionics (a Grand Rapids EIS) very close to where the left fuel line comes into the fuselage, I wanted to clarify the clearance issues there. I inserted a short piece of fuel line through the fuselage and slid the EIS into place. It'll be close, but as long as the fuel line bends forward immediately after passing through the fuselage skin, I think it will be fine.

I drilled out the fuel line holes on both sides to just under 7/8", and installed a rubber grommet in each. I'm glad I won't have to modify the fuel line entry point.

  Apr 02, 2009     Brake lines (prep work) - (2.4 hours)       Category: Fuel System

Entry 1 of 2:

Today I learned yet again to treat Vans diagrams like the US treats nuclear nation-partners: Trust But Verify.

When you fabricate the mounting plate (F-866D) where the brake lines pass through an elbow under the forward baggage compartment, Drawing 34 (Section B-B) shows a spacer on the forward side of the plate, used to take up the slack between the elbow fittings and the mounting plate. It calls out 0.063 stock as the material. Today I made the spacer and tried to install it, but it wasn't nearly thick enough. The elbows spun freely. I ended up making another spacer out of some 0.125 I had, and it worked fine.

While the paint dried on the new spacer, I tackled another brake-related project. I drilled a pair of 3/4" holes in the bottom of the gear towers where the brake lines will pass through. I had already marked the location for these holes when I mounted the Grove gear legs, so it was just a matter of drilling and carefully enlarging the holes from below. These holes will have grommets in them after I bend and install the brake lines.

Photo 1: Part on the left was made to plans. The one on the right is the proper thickness to do the job.
Photo 2: The hole near the top is where the right brake line will pass through on its way to the gear leg.

  Apr 01, 2009     Fuel lines - (4.0 hours)       Category: Fuel System

I spent most of the evening making and remaking a couple more of the fuel lines that attach to the fuel pump:

1. The one from the outlet of the fuel filter to the inlet of the pump. I finally made one that I liked.
2. The one that goes from the pump to the firewall. It has two 180-degree bends, which made it easier to make and install than a straight one. It also provides some strain relief.

Next I'll tackle the difficult ones that attach to the fuel selector. I think I'm going to use a lot of coat hangers while making those.

  Mar 29, 2009     Fuel lines - (4.0 hours)       Category: Fuel System

I clamped the fuel pump to its mounting bracket today, then began tackling the fuel lines. OK, an admission: Last fall I measured for, and ordered, a nice set of Bonaco teflon-covered flexible lines for both the fuel and brake lines, thinking they would save me some time and effort. I thought I'd just be able to screw them right on, clamp them down, and move along. Unfortunately, the larger "Dash-6" lines for the fuel system are a lot stiffer and less flexible than I'd counted on. The 90- and 45-degree fititngs I so carefully planned and ordered are totally inflexible, too, of course. There's no slop if you need another 5 degrees of bend within about 4 or 5 inches of the end fittings. This means the lines are nearly impossible to use in the locations I had planned. Today, I ditched almost all of them in favor of old-fashioned aluminum lines. This will give me a LOT more leeway with the bends and tricky angles in areas like the tight bend below the fuel filter, and underneath the fuel selector valve.

The first line I made was the one between the fuel filter outlet and the fuel pump inlet. I only had to make five of them before getting one that was perfect. Argh. Glad I ordered all the extra 3/8" tubing last month...

Photo 2: Used a coat hanger wire to figure out the fuel line bends.

  Mar 25, 2009     Fuel pump mount - (.7 hour)       Category: Fuel System

Not much time to work today, but I did get the Airflow Performance fuel pump bracket riveted to the floor.

  Mar 20, 2009     Fuel vent lines - (.9 hour)       Category: Fuel System

Installed the fuselage bulkhead fittings for the fuel vent lines. Because I'm using relatively stiff teflon-coated rubber lines instead of stock aluminum tubing, I reversed the bulkhead fitting so the 45-degree section was inside the gear tower. That made it easier to attach the lines, and will provide strain relief.

Finally, I installed the fuel vent lines themselves. This is SO much easier than bending aluminum tubes up inside the tight confines of the gear tower... I can't believe anyone would ever subject themselves to the hassle. I'll secure the loop with an Adel clamp at the top of the gear tower.

  Oct 19, 2008     Fuel selector - (.8 hour)       Category: Fuel System

I also riveted together the three support pieces for the Andair fuel selector, temporarily screwed the valve in position, and clecoed the whole assembly into the airplane. This will allow me to install the fuel lines.

  Apr 22, 2008     Fuel filter; Finish kit inventory - (1.8 hours)       Category: Fuel System

Today I installed the fuel filter on the forward face of the left gear tower. Because the drawings and instruction manual are somewhat lacking when it comes to describing the precise location of the filter, I selected the location based on a). laterally lining up the bottom fitting with the hole below, b). leaving enough room for the throttle quadrant cables that will run above it, and c). allowing for the easiest access through my custom fuselage access plate.

In keeping with one of my stated goals to make this airplane as easy to service as I can, I deviated from the plans a bit by installing nutplates for the AN-3 bolts that hold the Adel clamps. These were simple to install through the gear tower access panels. The platenuts seemed like a better idea than putting nyloc nuts inside the gear tower. Those seem like they'd be a pain to reach when I want to remove and inspect the filter each year.

Finally today, I inventoried and stored all the hardware in the Finish Kit. I only found one error: Vans sent me a bunch of dome-head AN470AD3-4 rivets instead of flush AN426AD3-4s. No biggie. I've got plenty of extras of each.

  Apr 02, 2007     Fuel sender/pickup - (.3 hour)       Category: Fuel System

Installed fuel pickup and clecoed anti-rotation tab (W-715) in place in L fuel tank cover. Test-fit L fuel level sender. (I'll permanently attach and ProSeal these components later.)