I am in the process of building the wings on my RANS S-19 experimental amateur-built (EAB) aircraft kit.  At present the popular engine is the Rotax 912 ULS.  I was thinking that by the time I am ready to choose the exact engine model (maybe 2 years) I may want to consider the 912is fuel-injected model.  My understanding is that the fuel-injected models require a fuel return line to each tank.  I am asking if it might make sense to plumb for these return lines when I am installing the fuel tanks in the wings?  Comments?

Another question: I saw a 912 fuel system drawing and it also showed a fuel return line to the tanks.  I was under the impression that the return lines were only required on fuel-injected engines?  I don't think my RANS kit has a return line to the tanks--is this a requirement?  Someone on my forum said that the return may go to the gascolator (and not all the way to the tanks)?

Thanks in advance for any comments!

Mike

  • Re: Fuel Return Lines?

    by » 4 weeks ago


    Yes it would be prudent to install a fuel return line during your build as Rotax requires a return line for both the carburetor and injected versions of their 912. I recommend you download the installation manuals for the versions you are considering.


    Thank you said by: Michael Tucker

  • Re: Fuel Return Lines?

    by » 4 weeks ago


    The return line is NOT an Arguable Option Option for the Fuel-injected engines.

    If you Plumb your wing tanks as a single tank (ON-OFF Fuel Selector Valve) with a generous (3/4") crossflow, you can return the fuel to either side without issue. 

    If the tanks are plumbed as two separate selectable tanks, (Off-Left-Right-Both Fuel Valve) the return line will need to switch in unison with the selected supply tank or the unselected tank will overflow in short order. 

    A Dual Off-Left-Right-Both Fuel Valve will be required.  $$$

    The return line has a 20-30 gallon per hour flow rate. (20-30gph is NOT a typo.)

    It is not uncommon for 100% of your fuel to pass through the engine multiple times during a flight.


    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    whertzel1@yahoo.com
    Clicking the "Thank You" is appreciated by all.

    Thank you said by: Michael Tucker, Dr William Scott

  • Re: Fuel Return Lines?

    by » 4 weeks ago


    If the Rans has a header tank, you can return to the header tank rather than the wing tanks.


    Thank you said by: Bill Hertzel, Michael Tucker

  • Re: Fuel Return Lines?

    by » 4 weeks ago


    Ken Ryan wrote:

    If the Rans has a header tank, you can return to the header tank rather than the wing tanks.

    Good point, Ken.

    As long as the header tank is vented, it will work.

    Some installation return to the unvented Gascolator.

    This is a bad idea as there are a lot of vapor bubbles generated by the pressure regulator that need to be vented.


    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    whertzel1@yahoo.com
    Clicking the "Thank You" is appreciated by all.

    Thank you said by: Michael Tucker

  • Re: Fuel Return Lines?

    by » 4 weeks ago


    Hi Bill, thanks very much for your reply.  Is your comment about returning the fuel line to the gascolator for the 912 ULS or the 912 iS (or both)?  My RANS S19 kit uses the 912 ULS and the return fuel line goes to the gascolator.

    Mike


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