Fuel Line Interference

Sometimes when you have a problem, everything you try does not work.  You have to just keep plugging away at it until something finally works.  The fuel line interference issue was just that sort of problem.

It was not until we mounted the wings that we noticed that there was a problem with the aft fuel line coming out of the fuselage, resting against the flap drive arm at the wing root.:

My first attempt to fix this involved shortening the fuel line and putting a new bead on it for securing the hose:

That solution did not work. As you can see, the hose will still have a problem getting past the flap drive arm.  There is not enough room between the fabric on the fuselage and the flap drive arm.  There is not enough room to go under the flap arm because the gap fairing that will go there will force the hose to rub against the flap arm.  You can't go over the flap arm, as that would create a high area in your fuel line system, that's actually higher than the (low) fuel level in the tanks. It all has to run downhill or you may run out gas before the tanks are empty (especially in a climb in this case).

Finally it dawned on me that the fabric in that area of the fuselage will not be exposed.  That area near the wing root will be covered by gap fairings.

The final solution involved making a 4" slice in the fabric opposite the flap drive arm.  This would allow the hose to go around the flap drive and clear it.

Problem solved right?  Wrong!  When I tried to bend the aft fuel line back into the slit so the hose would align better, the fuel aluminum fuel line kinked.  On to the part 2 of the fix.

In the cabin area, my aft fuel lines run down the aft door jam, covered by the fabric to hide them.  I sliced the fabric to expose the fuel line and just cut it off at the door jam.  Then a bead was put on the line to secure the hose. I then simply ran the flexible hose through the slit to make the connection inside:

It is visible and not ideal but it works to fix the problem.  The seat belt retractor system covers it up quite a bit anyway

Here is what it looks like on the outside now:

As you can see, I now have good clearance and no high spots in the fuel line.  Everything runs downhill.  I will clean the paint off the fabric at each end of the slit and then PolyTak a couple of pieces of reinforcement tape on, to strengthen the area of the cut.

If I were to do this again, I would fit the fuel lines during the initial fitting of the wings before covering. Like they say - hindsite is 20/20.

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