A step back on fuel lines
Posted in PlumbingWell, maybe the ease of installing those fuel lines yesterday was a sign that something was amiss. I realized after looking at some pictures on other web sites that I ran the lines through the largest (top) bushing, thinking biggest tube = biggest bushing. Not so…the largest bushing is for the wiring bundle.
Not a problem, right? Just get some 3/8″ vinyl tubing, slit it lengthwise, and slide it over the tube into the bushing to take up the space and provide cushion, then pull the bottom bushing, drill out the hole, and install another large bushing. Not so fast, according to a thread on VAF:
It is only Kosher if you don’t run any wires under it. Should you have a leak, the fuel could drip on the wires and that may not be a good thing.
Any Tech Advisor worth his salt would ask you to move the fuel lines to the bottom holes.
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….don’t run the fuel lines above the wiring….it’s not acceptable aviation practice (ie very dangerous).
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When in doubt you can always refer to the bible (AC43.13). Section 8 says: “Where practical, route wires and cables above fluid lines”.
Vans RV7 DWG 11 also specifically notes that the bottom snap bushing in the relevant cover support ribs (F-783B and F-783B) is an SB500-6 for the 3/8″ fuel line. The top snap bushings are an SB625-7 for the electrical wires.
Sigh. Looks like I’ll be ordering another spool of 3/8″ tubing. I almost put one on the last order…wish I had, it would have been a guarantee that the first time would go perfectly and I’d never need to touch the extra. I don’t know that I’ll be able to pull these out intact and have them be the correct length, etc.
