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A new day dawns and a new oil leak surfaces.  This 912 ULS with 1552 hrs has oil seeping from the upper front main bearing bolt, right above the mag plug.  The oil runs down along the side of the mag plug onto the lower front main bearing bolt and then is blown all over the #2 cylinder.  I have not checked the torque on these bolts because I seem to remember crankshaft binding problems associated with these two bolts.  In addition, the oil filter mount is in the way of the bottom bolt and would require removing the oil pump assembly to provide access.  What should I do to control this leak?    

8307_1_Oil seepage from thru bolt above Mag Plug.jpg (You do not have access to download this file.)

Jeffrey Fritts, USAF (ret.)

www.flywwlsa.com

"In aircraft maintenance, good enough is not good enough."

  • Re: Oil Leak at front case half bolts...

    by » 3 months ago


    Magnetic plug needs no washer. As shown in picture there is some metal washer showing.

    I think this washer leakage the oil.

    Remove the washer from magnetic plug.

     


    Thank you said by: Jeffrey Fritts

  • Re: Oil Leak at front case half bolts...

    by » 3 months ago


    The seal for that bolt is an Oring located at the case seam.
    The tighness of the bolt has no effect on the Oring sealing.
    Loosening and retightening the bolt may re-effect the seal but the Oring may just be deteriorating from age.

    Assuming that splitting the case to replace the Oring is out of the question...
    Pull the bolt and apply some silicon gasket seal on the shaft and reinstall.
    Or, swap out that Split Ring Lock washer for a copper sealing washer.
    Or, Both.


    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Bill.Hertzel@Yahoo.com
    Clicking the "Thank You" is Always Appreciated.


    Thank you said by: Jeffrey Fritts

  • Re: Oil Leak at front case half bolts...

    by » 3 months ago


    I agree with the above post. Remove the crush washer under the mag plug. It does not get a washer and is a metal to metal seal. This may easily be where the oil is coming from.


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-574-1080 Home (TRY HOME FIRST)
    520-349-7056 Cell

  • Re: Oil Leak at front case half bolts...

    by » 3 months ago


    Okay, okay the crush washer is coming off at the next mag plug check.  The leak started before the mag plug washer was installed, as an experiment. 

    Roger, I used your spray foot powder trick and it was definitely the top main crank bearing case bolt leaking.   

    Does that bolt have a different torque because of the special job it is doing?  

    27894_2_Detail of case bolt oil leak.jpg (You do not have access to download this file.)

    Jeffrey Fritts, USAF (ret.)

    www.flywwlsa.com

    "In aircraft maintenance, good enough is not good enough."


  • Re: Oil Leak at front case half bolts...

    by » 3 months ago


    Jeffrey, looking closely at your picture...  It may be just a photographic illusion, but it looks like there a crack in the case next to that bolt hole, starting about the 9 o'clock position of the bolt, continuing around to the 6 o'clock position, and then straight down for a little ways...  


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