[yankee-flyer]

I was talking with an FAA inspector at a meeting last night and he said one of the most common errors he saw in homebuilt airplanes was electrical wires tied to fuel hoses. There are several places where CHT, EGT, and other sensor wires are "routed along" fuel lines in the RV-12 instructions, especially the gascolator to fuel pump hoses. I took that to mean they should be zip-tied (plastic-tied) to the hose. Is this incorrect?

Thanks
Wayne 120241

 

[JBPILOT]

Just my guess - but

My guess is it is not best to tie-wrap to a metal fuel line. The ones "under the hood", have fire-protection and insulation, etc., so I dont think that would be an issue then. Scott can jump in if there is an issue.

John Bender

 

[Mich48041]

built according to ASTM standards

The exhaust gas temperature probe is a thermocouple that is only capable of putting out millivolts, no danger at all. The other sensors operate at 5vdc from the Dynon through current limiting resistors. The FAA might perceive this as a danger. But for practical purposes, the voltage is low, the current is limited and the fuel line and copper wire are separated by double insulation (fire-sleeve). Besides, the aircraft is built according to ASTM standards. If the inspector does not like the wiring, show him the pages in the plans that pertain. A bigger danger is bare aluminum fuel line in the fuselage. 12vdc wires should not contact those fuel lines because the insulation can wear through and the wire could arc and burn a hole in the fuel line.
Joe

 

[joedallas]

The exhaust gas temperature probe is a thermocouple that is only capable of putting out millivolts, no danger at all. The other sensors operate at 5vdc from the Dynon through current limiting resistors. The FAA might perceive this as a danger. But for practical purposes, the voltage is low, the current is limited and the fuel line and copper wire are separated by double insulation (fire-sleeve). Besides, the aircraft is built according to ASTM standards. If the inspector does not like the wiring, show him the pages in the plans that pertain. A bigger danger is bare aluminum fuel line in the fuselage. 12vdc wires should not contact those fuel lines because the insulation can wear through and the wire could arc and burn a hole in the fuel line.
Joe

Joe I think (no danger at all) should read (Very Little Danger)
Any wire that runs next to any other wire has Potential to carry the emf (electromotive force)of that wire.
Or any wire from any output device.

Joe Dallas
www.joesrv12.com