Hey all,


So I have never really noticed this until I started doing my own maintenance, and one step is to measure how much force it takes to pull the prop through, and noticed recently that if the bird has sat for a month or so, the prop pulls through really easy.

What I am saying is... when I turn up at the hangar and pull the prop through 5 or 6 times to burp the oil, she is really easy to pull through.  If I do the same thing after i go flying, she is a lot firmer.

Is this normal?  My LAME seems to thing it's OK.


She runs fine. Burns no oil, and is smooth.  She is a 912 ULS 2008 with about 350 hours on it.  All SBs up to date etc.


Any advice would be appreciated.

 

Cheers

J

  • Re: 912 pulls through easy when cold

    by » 3 weeks ago



    "She runs fine. Burns no oil, and is smooth."

    That pretty much tells you what you want to know.

    If you let it sit for over a month, it is likely that the Oil in the rings has drained out in that time and the seal is not what it is after a good oiling.

     

    As an experiment, the next time it feels easy to prop, try cranking the engine for an honest 10 seconds with the Mags OFF to build Oil Pressure.

    Then wait a minute to give the Starter a chance to cool and then crank it for another honest 10 seconds to get Oil into the far recesses.

    Then check again to see if the static compression hasn't improved.


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

  • Re: 912 pulls through easy when cold

    by » 3 weeks ago


    Thanks Bill,

     

    I am mot sure I can crank with the mags off - Mine are both on my ignition key. 

    The other way would be to pull all the pugs so it can't spark I guess.  


    Any other way?

     

    Cheers

    J


  • Re: 912 pulls through easy when cold

    by » 3 weeks ago


    Use one of theses to bypass the ignition switch. Connect from positive on battery to small terminal on the starter solenoid. I use it to crank motor after oil change to verify oil pressure before starting.

    https://www.harborfreight.com/search?q=push%20button%20starter%20switch


  • Re: 912 pulls through easy when cold

    by » 3 weeks ago


    Thanks!  Probably just as easy to pull the spark plug leads!  Can't start without them.  :)

     


  • Re: 912 pulls through easy when cold

    by » 3 weeks ago


    Not a good idea, as taught in the Rotax maintenance class at Lockwood Aviation the energy built up needs to be dissipated through the spark plugs. Damaged to your $900 dollar ignition modules can result if engine is cranked with spark plug leads removed.


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