Fuel System Installation #3 - Vents and Siphon Valve

Been working on the fuel system this week. All the fuel lines, vent lines and drain lines are done except the ones that will connect to the wing tank.

Here's an example of two vent lines that I finished today. I used tie-wraps and scrap pieces of rubber tubing as spacers between the tubes:

These two lines were originally passing just beside the fuel tank without going through the aluminium bracket. They were so long that I had to bend them every time I needed to remove/reinstall. I therefore decided to add bulkhead fittings (see top of the picture above) I found cutting the tubes in two halves is much easier to work with and also more convenient if I ever need to remove my main tank again.

Another new feature I installed is the siphon valve in the vent interconnect line between the header tank and main tank (see diagram here). It's a great idea suggested by my friend Mark Wood down in Wichita in order to avoid too much fuel being transferred back into the main tank while inverted. It is quite simple, avoids buying an expensive check valve and allows higher vent flow than a typical vented check valve. It is made by assembling two AN816-4D fittings in a AN910-1D NPT coupling with a ball in the middle. The only modification to be made is a castle shape on the bottom fitting to allow air to flow in the upright position. This is reasonably easy to do with a file. See below:

Here's what it looks like once installed on the airplane. Assembly to be secured with either Adel clamps or Koroseal lacing.

Next task is to start reconnecting wires. Stay tuned!