Fuel line routing/install

OK, so yesterday I got my (second) fuel hose from AS Flightlines, and this time I got the hose size right. Getting it installed and properly secured seemed like a nice little evening task. The routing was easy since I’d previously figured out the general idea, and just needed to tweak some things a bit, most notably the clocking of the 90° fitting on the outlet side of the mechanical pump.

The real fun was in securing the hose. I had two points where I wanted to use double adel clamps, one on a mount tube and the other on an intake pipe. Thing is, adel clamps are kind of fun to work with – you’ve got to squeeze the ears closed and hold the thing in place while also putting a bolt through it and starting a nut. And that’s just one clamp – with this setup, I had to do that with two clamps at once.

Fortunately I’d previously read about a technique for handling this – using safety wire to hold the ears of each clamp together. I’d hoped this would be a way to use up the really fine wire that came in my safety-wire kit, but turns out that stuff isn’t stiff enough to really pull the clamp ears together. Oh well.

Anyway, things are wrapped up now. The line exits the pump, then heads over to the right side of the engine. It gets secured to a mount tube as it crosses under:

Then it makes the turn forward and is secured to the #3 intake pipe:

And finally it loops around front to the injection servo. I’d initially thought I’d secure it to the prop oil line (the hard tube visible nearby), but there doesn’t seem to be enough freedom of movement here for there to be a chafing issue. It’s possible I might change my mind in that, though:

The rest of the work was getting the end fittings torqued, along with the clocking and torquing the 90° adapter fitting on the pump.

I did run into one possible hangup, though, which can be seen back in the first photo. Van’s provides another 90° adapter fitting on the inlet side of the pump, and I figured I’d replace the 45° one that came with the engine while I was in the neighborhood. Unfortunately, trying to thread it out of the pump, it interferes with the governor mounting pad after only about one turn. The only way to remove that fitting seems to be to loosen and/or remove the mechanical pump.

I’m hoping I can get by with the 45° fitting and not deal with removing the pump – I suppose once i get this hung on the fuselage again, doing a test-fit of that fuel line will be on the short list of things to do.

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