fuel injected engine

[buchdvm]

Fuel Injected engines are becoming more available but there seem to be a lot of differing opinions as to how the fuel lines are installed. One question I have is a header tank preferable over a gas selecter valve, another is a gascolater not necessary for fuel injected engine? Will automotive fuel lines be more than acceptable ?

[Mike M]

1. what make/model engine?
2. what make/model fuel injection?
3. a major function of a fuel selector valve is the shutoff feature, so one may prevent fuel passing the firewall into a burning engine compartment. i don't understand how a header tank could substitute for that feature.
4. opinions vary on whether a gascolator is necessary with some makes/models of fuel injection, or with fuel injection systems in general. many facts support each of those varied opinions. without the answer to #2 above, there is no way to definitively answer this question, even if opinions didn't vary. so. it's your body, your money, your experimental aircraft, do what you want and some will call you genius, some will call you ignoramus.
5. aluminum fuel lines, no problems. steel fuel lines, why use them? "rubber" fuel lines? automobile "rubber" fuel lines are acceptable for their designed purpose, automobiles. not "more than acceptable". given that, i fail to understand how anything could be "more than acceptable" for any purpose it was NOT designed for. but there is no need to be "more than acceptable". in my opinion and experience, quality automotive fuel lines that meet the spec for installation in the latest flex-fuel vehicles will be acceptable for transferring aircraft fuel. whether you put them in your experimental aircraft or not, see #4 above.

your mileage may vary. let us know how it works out.

[WLIU]

If I may offer some points, first, if your automobile's fuel line ages and fails, you can pull over to the side of the road and run away. Much harder to do in an airplane, so we want stronger and more reliable components.

A fuel injection system requires much finer filtering than a carburetor. The injector nozzle openings are around 0.020", so it does not take much to clog them. So we first need a gascolator screen to catch the big stuff. Then the fuel control has a fine screen to catch the stuff that makes it past the gascolator. The drain on the gascolator also dumps the stuff that the screen stops and if the gascolator drain will not close, we get the hint that some "stuff" might be in the gascolator and opening and cleaning the screen might be a good idea. Interestingly, Cessna gascolators have a clear bowl so you can inspect what's inside as part of your airplane preflight. I will suggest that this is a good idea and I have not heard that these gascolators add any additional hazard over gascolators with aluminum bowls if you crash.

The fuel system lines are typically aluminum behind the firewall. These lines are inexpensive and last a very long time. Forward of the firewall you typically find hose that is constructed of layers of high quality rubber with stainless steel braid in between layers, then the hose is covered with a fire sleeve that insulates and resists flame. An alternative is hose made of a teflon tubing with stainless steel braid over it, then maybe fire sleeve again. Flexible to resist vibration and engine movement, and very strong. Lots of vibration and a surprising amount of engine movement forward of the firewall. Steel lines crack due to vibration and rust when exposed to the elements and heat from the exhaust system. My plow truck, which admittedly lives a hard life, has had the steel brake lines rust and fail suddenly, the steel transmission oil cooler lines rust and fail, and the steel tank for the power steering pump rust and fail. Aircraft hose would have lasted much longer.

So go look at the standard aircraft references for fuel systems, like AC43.13, and follow those practices. Or wear a parachute and bail out at the first sign of smoke.

Best of luck,

Wes
N78PS