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Whilst perusing the new 912 Line Maintenance Manual I noted the recommended cold engine spark plug tightening torque has changed significantly.  It appears we’ve all been over-tightening them for years.  Anyone have any idea why the change?

  • Re: New Line Maintenance Manual

    by » 3 months ago



  • Re: New Line Maintenance Manual

    by » 3 months ago


    Thanks. Allow me to rephrase my question. Why would a spark plug with an adjustable ground electrode require significantly more tightening torque than a spark plug with no adjustable ground electrodes?


  • Re: New Line Maintenance Manual

    by » 3 months ago


    I am only making a wild guess based on no facts here.

    The difference probably has less to do with the Electrode design and more to do with the construction of the body.

    Assume the old plug had a steel body and the new plug has an aluminum body.

    The aluminum body would suggest that a lower torque would be recommended.

    The advantage of an aluminum body would be a 5 times greater thermal conductivity compared to a steel body.

    - - -

    Disclaimer:  I have never examined the new plugs and do not know what material they are made from.

    This is all just speculation.  You asked, "Why?". This is a Possible answer.


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


  • Re: New Line Maintenance Manual

    by » 3 months ago


    Dear ROTAX reps:  The new LMM (in particular Section 05-20-00, Page 14, Item 11) does not indicate the requirement for a 100-hour inspection of the propeller "friction torque" as was formerly required.  The more intensive 600-hour/1,000-hour gearbox check is mentioned but not the simpler 100-hour propeller "friction torque" check.  Is this a misprint or a change in inspection requirements?


    Thank you said by: RotaxOwner Admin

  • Re: New Line Maintenance Manual

    by » 3 months ago


    David HEAL wrote:

    Dear ROTAX reps:  The new LMM (in particular Section 05-20-00, Page 14, Item 11) does not indicate the requirement for a 100-hour inspection of the propeller "friction torque" as was formerly required.  The more intensive 600-hour/1,000-hour gearbox check is mentioned but not the simpler 100-hour propeller "friction torque" check.  Is this a misprint or a change in inspection requirements?

    Thanks for the heads-up, David! That is a misprint/omission.

    The 100-hour inspection is still a requirement, and will be added back to the manual in the next revision.


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