Dean, I wouldn't be afraid of using barbed fuel fittings and for that matter plastic fuel lines, depending on the application. They are widely used in Ultralight, Light Sport Aircraft, and many Experimental-Amateur Builts in the US. There are some excellent (tough) plastic fuel lines on the market these days. Many builders, if not most, use safety wire instead of the worm gear type clamps which have been known to break or become loose over time. In Krs, such plastic lines have been used successfully (mostly aft of the firewall) for sight gauges, auxiliary fuel tanks, conduit for wires, etc. Some common sense needs to be used in considering placement away from a high heat source and in bend radiuses so they don't pinch off. Where fuel lines are visible, it's comforting to be able to see fuel flowing through them. I use clear plastic lines on my Minimax which can be inexpensively replaced every couple years as a part of routine maintenance. They can also help reduce the possibility of restricted fuel flow by reducing the number of fittings used in the fuel system and the flexibility can help absorb engine vibration.
Ed Janssen > There is widespread condemnation of the practise of using barbed fittings > and hose clamps in an aircraft's fuel system plumbing. Could somebody in > the know please tell me why this is so. I can't think of any reason why > using a good quality reinforced "rubber" hose with fire sleeve over it > (forward of the firewall) would be in any way inferior to using aluminuim > piping and AN fittings. In the event of a mishap and things move around, I > can't see how the solid installation will be superior to the rubber hose > as it will not have near as much flexibility to absorb the movement. I > would imagine that an aluminuim pipe would be much more prone to cracking > and leaking when kinked. > > Over here the practise of using barbed fittings and flexible hose is > almost universal unless you are assembling a RV kit which comes with all > the appropriate AN fittings. > Am I missing something here? > > Regards > Dene Collett
