Roee Kalinsky's RV-7A Project

2006.05.23: (0.0) Since I'm planning on a fuel-injected engine, I'll need a high-pressure (25 psi) auxiliary fuel pump, rather than the standard low-pressure pump used for carbureted engines.  I'm using Van's kit "7/7A F.I. PUMP INSTAL", which includes an Airflow Performance p/n 3090050 boost pump package, an Airflow Performance p/n 1090079 fuel filter, and various parts for installation in the cockpit.  The Airflow Performance 3090050 boost pump package consists of the following pre-assembled components: p/n W-7135X pump motor, a 25 psi relief valve, a swing check valve for bypass, and a manifold, fuel line, and fittings that put it all together.

Unlike the standard low-pressure pump which mounts on the firewall, the high-pressure pump mounts on the cockpit floor under the fuel selector.  This requires modifications to the cockpit structure in the area of the fuel selector.  See section Cockpit Floors and Covers, entries starting with 2006.05.23.

2006.07.08: (1.0) Mounted the electric fuel pump and fuel filter on the bottom cover plate.

2006.07.14: (3.0) Practicing and experimenting working with the 3/8" aluminum tubing and tubing tools.

Measured that 3/8" tube should be cut approx 0.090" longer at each end than the edge of the fitting it'll mate with for good fit after flaring the end.

Found that the tubing bender I bought (Imperial 368-FH) will only do up to 90 deg bends.  Several attempts at several different techniques to produce a 180 deg bend just didn't yield good results.  I decided to purchase another tool that's designed for 180 deg bends (Imperial 470-FH).  [P.S. The 470-FH turned out to be a better tool all around, able to do everything the 368-FH could do and more.  To my annoyance, the 368-FH cost me $41.60 and the 470-FH cost $27.60, both at Aircraft Spruce.  Even more infuriating, I later found a tubing bender that looked identical to the 368-FH at Home Depot (apparently a generic knock off) for about $10!  @#$%!  After seeing this, I went back and compared pricing for other tubing tools.  I found that Spruce was very inconsistent on other tools as well.  Sometimes they're competitive, and sometimes they charge several times more than other stores for the exact same item.  Many of these very same tools can be had at Home Depot or Sears for a fraction of the price.  Spruce shoppers beware!!!]

2006.07.16: (3.0) Started making my first fuel line, from the fuel filter to the fuel pump bypass check valve (tee fitting at the check valve also goes to fuel pump input port).  The first attempt came out nicely, except that the straight sections at the ends weren't long enough to put on the AN819 sleeves and get the remaining end of the tube into the flaring tool.  The sleeves are approx 0.5" long and the flaring tool is approx 0.75" deep, so at least 1.25" of straight section has to be left at each end of a tube.

2006.07.22: (3.5) Finished making the fuel line from the fuel filter to the fuel pump bypass valve.  Used a crow's foot perpendicular to the torque wrench to torque the fittings.

I decided to use an Andair fuel selector valve instead of the valve that comes standard in the kit.  The decision wasn't aesthetic (even though the Andair valve is a beautifully machined work of art, and the standard valve from Van's looks like it belongs at the end of a garden hose).  The standard valve from Van's has a handle that extends opposite to the selected tank, which I find objectionable from a "human factors" standpoint.  Also, there are tactile detents in the three positions ("left", "right", and "off") but no positive mechanism for ensuring the valve is in the desired position.  The Andair valves on the other hand have a handle that clearly points to the selected tank.  The handle hits a positive stop at "left" and "right", and a safety button has to be lifted to move the handle in or out of the "off" position.

As another "human factors" improvement, I decided to mount my fuel pump switch right above the fuel selector valve rather than in a row of other switches on the panel.  The fuel pump and fuel selector valve are functionally related, and placing them next to each other facilitates a natural "flow" when performing various checklist procedures.  Also, having the fuel pump switch away from any other switches ensures that it can be operated safely by touch without looking, with no danger of mistaking it for a different switch.  The fuel pump switch will have three positions: "ON" (up), "AUTO" (center), and "OFF" (down).  Normally the switch will be on "AUTO", where the fuel pump is controlled by the FADEC, except when switching fuel tanks, emergencies, etc.  An annunciator light on the panel or on the EFIS screen will warn if the switch is in a manual override position ("ON" or "OFF").

Owen at Andair advised me that their FS20X7T is the best choice for the RV-7A, as it was designed to fit without too much trouble into the existing design.  As Van's now carries these, I bought one through them.  Although I'm very happy with the quality of the valve, it seems that the choice of fittings on it could have been better.  It has all built-in fittings for flared tubing, which leaves little flexibility.  Female pipe fittings would have been better, so that any of a number of standard AN fittings could have been used to direct the ports before going to a tubing run.  In particular, the output port from the fuel valve needs to immediately tee off to the fuel filter and a return from the pressure regulator valve.  Being a flared tube fitting on the Andair valve, I had to get a female swivel fitting with the appropriate tee.  This is an AN-like fitting, but is non-standard and hard to find.  "Luckily", Van's now carries these (Van's p/n "F SWIVEL TEE") at twenty bucks a pop.

2006.07.30: (3.0) Made two more fuel lines.  One from the fuel selector valve tee to the fuel filter.  Another from the pressure regulator valve back to the fuel selector valve tee. 

2007.??.??: (0.0) [This entry covers the past few weeks]  Moving on to the left and right fuel lines to the fuel selector, I found that I simply couldn't make the geometry work.  The "flared tube elbow fittings" on the Andair FS20X7T would work great on a carbureted RV, but for a fuel-injected RV like mine, the tubes and fittings on the Airflow Performance high-pressure fuel pump interfere with the lines coming off the fuel selector.  A quick discussion on the Van's Air Force (VAF) forums confirmed the diagnosis, and the best cure others have found are the Andair BF20 "banjo fittings" instead of the elbow fittings.  Exchanged a few emails with Owen at Andair, who also suggested the banjo fittings, and offered to swap. 

2007.??.??: (4.0) Received the Banjo fittings from Andair, which indeed made the fuel line routing more feasible.

2007.05.18: (4.0) Made the in-cockpit tubing for the left fuel tank vent.  First used copper wire to model the rough shape, then bent and fitted the actual 1/4" aluminum tubing.  Note that the location for the bulkhead fitting that goes through the side skin to the wing has still not been precisely determined, so I left that end long for now.  The location for the fitting is not precisely shown in the plans, nor is there a pre-punched pilot hole as stated in the plans.  Since it's a fairly tight area near the leading edge of the wing, I'll wait until I have the wings on to determine the precise location for the fitting.

2008.05.28: (0.0) Modified a pair of AN bulkhead fittings to use as the fuel tank vents.  Took off the thread on one side with Vay's lathe, and also thinned out the flange some to reduce drag.  Then I cut a 45 degree angle on the bandsaw, and cleaned it up with a file.  Came out pretty nice.

2011.09.29: (0.0) The lengths of fuel hoses supplied with Van's firewall forward kit did not fit my particular installation, so I returned them and instead had custom hoses made by Precision Hose Technology, Inc. of Tulsa, OK.  And since I'm having them custom made anyway, I also used a better more modern type of hose.  Van's uses Aeroquip AE701, which is a synthetic rubber hose with stainless steel braid jacket, and a slip-on firesleeve.  It is rated for operating pressure up to 1000 psi, and temperature of -65° to 300° F.  The hose type I selected is Parker Stratoflex 124J.  This is a teflon hose with stainless steel braid jacket and integral firesleeve.  This hose is rated for operating pressure up to 1500 psi, and temperature of -65° to +450° F (-54° to +232° C).  And whereas synthetic rubber hose has to be replaced every few years, teflon hose has virtually infinite service life.  It is well suited for firewall-forward fuel lines, and is often used as such in certified aircraft.

The hose specifications I used in my installation:

Firewall to engine-driven fuel pump:
3/8" ID (-6), straight to 45° elbow, 9.0 inches long, p/n 124J003-6CR0090

Engine-driven fuel pump to fuel injection servo:
3/8" ID (-6), straight to straight, 26.5 inches long, p/n 124J001-6CR0264