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Oil psi drops the higher I climb

in 912iS Technical Questions 6 years ago

  • Re: Oil psi drops the higher I climb

    by » 6 years ago

    Put a Tee in where the oil pressure is taken and have two items coming off one port for a temporary test.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: Oil psi drops the higher I climb

    by » 6 years ago

    On a 912iS it is much easier to use a double banjo off the oil pump/gov supply port.
      
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  • Re: Oil psi drops the higher I climb

    by » 6 years ago

    Alright so yesterday I installed an analog gauge as Rob suggested by doing double bango fitting and went for a test flight. I can now confirm that the dynon sensor is functioning fine, I am losing pressure the higher I climb. I lose about 3psi per thousand feet. I also played around with the throttle and prop controls while at 10,000’ and found that as soon as I reduce throttle to idle the pressure goes up from 23 to 45 psi. As soon as I put power on pressure drops back to 23. Same goes for using the prop to control rpm, if I drop rpm with the prop pressure goes up, if I go to cruise setting pressure drops again. This seems to go against all physics logic, pressure I don’t think should drop with less rpm, nor should it drop so much with altitude increase. There are three pipistrels in my area, one other one is identical to mine, so 912iS with mt prop and has the same issue as me just not as bad of pressure drop. The other one is a 912iS with electric constant speed with no issues, has good pressure at high altitude. I’m tempted to test fly with prop hydro line disconnected, as long as it doesn’t go into course pitch with no oil pressure I should be able to test it at fine pitch to see if somehow the prop is causing this pressure drop.
      
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  • Re: Oil psi drops the higher I climb

    by » 6 years ago

    I will be replacing oil lines this week. It’s possible an oil line is collapsing in when more power is applied, would explain how. Pressure rises when I go to idle as this would release suction pressure on the lines and open it up allowing oil to flow.
      
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  • Re: Oil psi drops the higher I climb

    by » 6 years ago

    I have had a few aircraft that because of hose routing the hose pinches down some when hot due to sharp bends. It doesn’t take much for some hoses. I have corrected these issues by either re-routing the hose or inserting a spring into the hose at the critical point. This is very easy to do and has helped all the owners by allowing better oil flow which has decreased temps.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report
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