fbpx

 

I have an ELSA with a 912 ULS.  Since new it has had fuel pressures that jumped all over the place.  The previous over installed new fuel pump as directed by Rotax etc.  now the pressure is going too high.  I am planning on cleaning the fuel system and replacing all the hoses.  
I am seriously considering using a bypass fuel regulator  instead of the restrictor in the return line.  My thoughts are that I will get a more consistent pressure than the restricting orifice in the return line and I can adjust pressure. Anyone else try this?

 

Terence

  • Re: Bypass fuel pressure regulator

    by » 2 weeks ago


    Hi Terence,

    Last question first - my last aircraft came with an adjustable fuel pressure regulator. The aircraft/engine predated the fixed bleed/return line manifold now installed in most, if not all, Rotax 912 fuel systems - Yes it worked. However the penalty is considerable extra weight & complexity. Hardly desirable.

    My understanding of the fixed orifice manifold/ return line has more to do with vapour mitigation than pressure regulation.

    Assuming the correct mechanical fuel pump had been fitted and all fuel lines are in good order (last 5 year rubber replacement?) - I cannot see how you can have "too high" pressure. The mechanical pump will only deliver at the specified fuel pressure & volume.

    What fuel pressure readings have you seen?

    Have you verified this pressure using a master gauge? or even a temporary replacement?

    Pressure gauges using a "Bourdon Tube" usually have a restrictor in the pressure line/or gauge to smooth out the pulses - If this is the type of gauge you have, the restrictor may be missing.

    Describe the fuel pressure gauge.


  • Re: Bypass fuel pressure regulator

    by » 2 weeks ago


    You are correct the 912 didn’t originally have the return line and the pressure was within limits.  I have a VDO sending unit going to a Grand Rapids Engine Information System. 

    Thank you for you reply.  It gave me some ideas.  The VDO sending unit has a metered orifice to smooth out the pulses.  

    Terence


You do not have permissions to reply to this topic.