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Fuel return lines

dicel87

Well Known Member
In one of the videos, Ken discusses the fact that the RV-14 is designed so that return fuel lines can be easily incorportated.

What is the significance of this?
 
Some fuel injection systems use return lines.

Airflow Perf for one.

I suspect that a FADEC system with electronic FI would have return lines also.
 
Correction

Airflow Performance fuel injection systems DO NOT require a return line to the tank. If the system incorporates a purge valve, the purge return line is typically teed into one of the fuel tank feed lines. If the fuel injection system is using a FM-150 fuel control there is no purge valve supplied with the system.

Don
 
The ECI injector looks like a Continental continuous flow clone, so it would have a return from the vapor separator in the pump.
 
FADEC

I wonder about the FADEC comment. I seem to remember around 2008 or 2009 Lycoming was talking about the ie2 540 in the lancair and that they would move into a 4 cylinder version based on the 390 once it was more proven(at the time, I bet Lancair looked like a pretty good cash cow to help fund the research) I can't seem to find it in the lycoming archives at the moment.
 
The ECI injector looks like a Continental continuous flow clone, so it would have a return from the vapor separator in the pump.

This.

The ECI system is expensive, and finicky to get adjusted right when you first set it up, but once its calibrated by someone who's experienced with them, is a wonderful performing fuel injection system that makes child's play out of hot starts. My friend's RV-8 that I helped build and got to fly for a couple years has the ECI system and based on my hands-on experience with it, would be a very nice system to put onto an IO-390. It does require the Andair "duplex" fuel selector valve, which is kinda like a DPDT switch, so that the return flow gets sent back to the same tank you're feeding from.
 
ECI

Mine is an ECI FI system and it works like a charm. I have no complaints at all. Install the system per plans and then set it for 1250 degree maximum EGT at full throttle for sea level takeoff and you will be a happy pilot.
 
same story here,

we also have the eci fuel injection system on our mattituck tmx-io360 and could not be happier :)
hot starts are a piece of cake, temperatures/fuel flow can be very tightly controlled and all cylinders run almost perfectly even.

the andair dual fuel selector is hilariously expensive compared to the single selector (and part of what makes the eci system more expensive), however quality is top notch and there's no real alternative out there.

i see the fuel return line decision on the rv-14a as very wise... i would definitely install one at the time of build, even if the engine at the moment doesn't require it.

most developments foreseeable (car gas / jet-a1 diesel engines, the continentals under development?) are likely to require a return line or at least make operation much safer/more reliable, considering the rather small effort for the return line.

regards,
bernie
 
Return to one tank only?

Although it would require some fuel management care, one could have the return line plumbed to one tank only. A simple furel selector valve suffices. Some of my old Bonanazas had this system, where the auxes would all return to the left main. One flies of the tank with the return first, making room for the fuel. Switching to the second tank fills the first one. Not that big a deal once one gets used to it.

Rafael

RV-8A flying
RV-12 just about ready (undergoing PAP )
Will have to sell one of them to build the -14. Decisions, decisions...
 
As Don mentioned above, the AFP purge valve is teed into the fuel line ahead of the fuel selector, typical under the right seat. Set the fuel valve to the left tank for cold fuel and pump the hot fuel into the right tank. Pretty easy and straight forward.
 
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