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Rotax's service instruction for installing cylinder heads talks about both heads on one side of the engine.  I only need to replace one head.  Should I also loosen the nuts on the adjacent head and follow the service instructions or leave well enough alone.  


Jeffrey Fritts, USAF (ret.)

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

  • Re: Cylinder Head si-912-025

    by » one month ago


    I believe in order to use the tool they recommend to keep the two surfaces level and parallel you will need to loosen the bolts on the good cylinder. Be sure to use the new method to properly torque all the bolts.


    Thank you said by: Jeffrey Fritts

  • Re: Cylinder Head si-912-025

    by » one month ago


    And get new bolts in, too.


    Thank you said by: Jeffrey Fritts

  • Re: Cylinder Head si-912-025

    by » one month ago


    James, 

    Thank you for your quick reply.  That is a good point.  I do have the Rotax alignment plate and in order to get the perfect flat surface for the intake manifold to remount would require loosening the adjacent cylinder head.  


    Jeffrey Fritts, USAF (ret.)

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


  • Re: Cylinder Head si-912-025

    by » one month ago


    Peter, 

    You make a good point.  EAA just this month ran a webinar with Mike Busch about replacing cylinders.  Although he was talking about Continental and Lycoming engines where the head and the cylinder are assembled together as one unit and there are thru-bolts that hold the case halves together involved.  Our Rotax engines are not designed in this way.  Replacing hardware was an important point of making sure the engine didn't have failure soon after the work was done.  I'm surprised Rotax doesn't specify using new hardware.   

    Here is the URL to an article that talks about the same information presented in the webinar.  https://resources.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2014-06_cylinder-work-be-afraid.pdf


    Jeffrey Fritts, USAF (ret.)

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


  • Re: Cylinder Head si-912-025

    by » one month ago


    Gentlemen,

    Boy, do I feel foolish.  I knew there was a new service instruction out about the tightening torque procedure for the heads and watched the video to refresh my memory, but...

    After reading through the actual service instruction si-912-025 on page 5 under Fig. 1 there is a note.  And I quote,

    "NOTE: The installation and tightening of a single cylinder head or any individual cylinder head nut is not allowed. The entire procedure to torque both cylinder heads together in one torque sequence must be performed."  

    Guess that answers my question and you learn something new every day. 

    RTFM - Read The Fine Manual


    Jeffrey Fritts, USAF (ret.)

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


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