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propeller bolts

Category: 912 / 914 Technical Questions one month ago

My propeller is mounted with 6 m8 bolts and locking nuts. I would prefer to use drilled shank bolts and castle nuts so that I could get a more accurate torque. Are m8 drilled shank bolts available? How about using AN 5 bolts?

  • Re: propeller bolts

    by » one month ago


    Not sure how that is going to give you a "More Accurate Torque"?

    You will torque the Nuts to what you believe to be the exact spec number and then turn them one way or the other to get the hole to line up with the castle.  There goes the Spec!

    The amount of drag introduced by the Lock-nut is less than the tolerance of your Torque wrench.

    An M8 Lock Nut is typical ~5 in∙lbs on the first use and <1 in∙lb if reused.  Is your Torque Wrench that accurate?

    In any event, the Propeller manufacturer has already has taken the Prevailing Torque of the Lock Nut into account when specifying the proper Torque needed. (And then rounded it to the nearest 5 in∙lbs.)

    The Standard Torque for an M8 Bolt varies from 220 to 265 in∙lbs depending on who you ask.

    5 in∙lbs one way or the other is not significant.

    You are making this way too complicated.


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

    Thank you said by: RotaxOwner Admin

  • Re: propeller bolts

    by » one month ago


    You are right Bill. I was thinking the drag on the thru bolt and nyloc nut was higher than that. Tried it today and the total drag on the used bolts and nuts is less than 5 inch pounds. I'm happy now.


  • Re: propeller bolts

    by » one month ago


    The drag from the Bolt is more significant than from the nut.

    When Tightening, you will want to put the wrench on the NUT and counter-torque the BOLT if physically possible.


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

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