REFLECTOR: fuel system venting

[Ron Brown]

Here's a suggestion for you - this is how I built my vent lines in the tanks:

I ran a piece of 3/8" tubing from the top rear of the fuel tank, to the outer edge of my RG tub for the wheel.  From here I connected a piece of wire to the metal ring on my fuel filler cap. This provides a ground to the aircraft ground system to help relieve sparking while refueling.  I drilled about 4-5 holes in each vent tube along the way.  I epoxied the tube to the fuel tank wall after roughing up and cleaning the aluminum tubing.  Use a flox paste of epoxy.

Hope that helps.  Oh, and it took me over a month to build my strakes.  The 2nd one will go much quicker.

Ronnie
  ----- Original Message ----- 
  From: Grigore Rosu 
  To: Velocity Aircraft Owners and Builders list 
  Sent: Saturday, February 02, 2008 3:54 PM
  Subject: REFLECTOR: fuel system venting


  Thank you for your answers on the finger strainer; I guess I'll install the hardpoint and the finger strainer.  This is very frustrating, though, because it means one more week of waiting until the strainers come; I thought I could finish it this weekend.

  I'd like to ask another question, this time about the venting line.

  The attached picture shows where the 3/8'' hole for the vent line comes in my SEFG (just drilled it).  Note that I built a little foam-supported flange on the fuselage to support the top strake.  The flanges are not sanded yet.  To get my vent as high as possible, I had to drill through that foam.  I inserted a 3/8'' aluminum line in the hole to make it more visible in the picture.

  The manual calls for a hardpoint for the venting line on the fuselage.  First, there are no such hardpoint parts in my kit.  Second, the manual says nothing about what happens from that hardpoint inside the fuel tank.  Are we supposed to just let an open hole there?  How can we make sure that no leaks find there way around that hole?  In case we are supposed to seal that hole with jeffco, it still appears to be difficult to make sure no pin holes are left, not to mention that it can be difficult, or in my case impossible, to paint the inside of the hole.

  I find it strange that the manual does not require a hardpoint for the fuel line, but it does requires a hardpoint for the venting line.  Since at this moment my hole trough the fuselage and the flange-supported foam for the venting line has about 2.5'' in legth, I'm thinking of doing the following:

  1) enlarge the hole to 1/2''
  2) bond the pipe with structural adhesive all the way throught the long hole and 4-5 inches in the tank
  3) even though I don't see why it would be necessary in this case, I can also place a 1'' x 1' x 1/8'' hardpoint on the interior of the fuselage that would bond the aluminum line even better.
  4) use no AN blue connectors for the vent lines on the fuselage; in other words, take the vent lines all the way from the manifold to fuel tanks, bonding them properly on the fuselage.

  Does anybody see any problem with my approach above?

  I understand that the connector is useful on the fuel line in order to take out and clean the finger strainer, but why would the connector be useful on the venting line?

  Thank you,
  Grigore



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