At the risk of stating the obvious, do you really need conduit at all just to run wires to the back of the plane? Maybe through a wing or someplace you can't get to, but how many wires do you need to run to the back of the plane anyway? On both N56ML and N891JF I simply clamped them to the longeron at each vertical intersection (every 14" or so) with small plastic pclamps secured with a #4 wood screw, and tied them up with tiny (light) tie wraps or wiring loom thread (even lighter) to keep them together around corners. Continuous conduit like PEX would be a real pain to add a new wire to. I used wire ties from trash bags to hold them together as I built the plane, and then when I knew I was done, I swapped out the wire ties for tie wraps to clean it up and "do it right".
Another consideration is crosstalk between stuff like strobe lines and antenna coax....even antenna coax and the trim tab control wires (which will fry your trim tab indicator LEDs). So I ran the antenna coax by itself under the left longeron, most other stuff down the lower right longeron, and a few odd balls at other longerons, splitting them up to keep from interfering with each other. There's a lot of flexibility in "open air" runs of wire, and done properly it looks nice, is easily altered, runs cooler, and most important of all, it weighs practically nothing! It all adds up, and before you know it, your plane is a pig... Mark Langford, Harvest, AL ML at N56ML.com www.N56ML.com
