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Hello Guys,

I have a Rotax 912 on a Rans S12-XL I am going to intall a 3 blade Warp Drive Prop.

I have the following:
One Set of 6 press fit lugs Rotax Part No.842-634
Six Prop Mount Bolts 8mm X 75 drilled head.

I was checking page 121 on the Rotax Manual about what torque to use on does prop bolt and it say:

ROTAX 912 UL, A, F for i = 2,2727: 238 Nm (176 ft.lb.) (at propeller)
ROTAX 912 UL, A, F for i = 2,4286: 255 Nm (188 ft.lb.) (at propeller)
ROTAX 912 ULS, S for i = 2,4286: 315 Nm (232 ft.lb.) (at propeller)


Then on Warp Drive web page it say the following:

Propeller Bolt Torque Values--All Standard, HP and HPL hubs that use 1/4" bolts to clamp the blades in the hub should be tightened to 120 inch pounds. All Rotax bolt patterns that use 8 mm bolts to mount the prop to the gear box flange should be tightened to 175 inch pounds. All Standard, HP and HPL hubs that use 3/8" bolts to clamp the blades or mount the prop should be tightened to 35 foot pounds. Warp Drive propeller installations on direct-drive aircraft engines and other engines used on airboats must tighten the 5/16" clamping bolts to 200 inch pounds and tighten the 1/2" flange mounting bolts to 60 foot pounds. Adherence to these torque values is imperative for reasons of safety.

I am including here a pic of my warp drive prop

So whats your advice????

THX,

Isaac

 

 

xxxxxxmywarpdriveprop.JPG (You do not have access to download this file.)
  • Re: Prop Bolt Torque Confution

    by » 9 years ago


    Hi Isaac,,
    You got it right. "All Rotax bolt patterns that use 8 mm bolts to mount the prop to the gear box flange should be tightened to 175 inch pounds". I just took a Warp Drive off a plane today to test a new 68" 3 blade Sensenich.

    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: Prop Bolt Torque Confution

    by » 2 weeks ago


    So you are saying the rotax manual is wrong?


  • Re: Prop Bolt Torque Confution

    by » 2 weeks ago


    I can see how this is a little confusing and happy you posed the question! You are reading the manual incorrectly. The 315 NM (232 ft, lb) Is the max TQ the propeller shaft can be subjected too, not the TQ spec for the bolt to attach the propeller.  The propeller manufacturer sets out the torque limitations for the attachment bolts. 

    Example:

    In the case of a Warp Drive propeller, the bolt TQ is:

    AN4-20A Clamp bolts - 120 in/lbs, 10 ft/lbs 

    8mmx75mm or 8mmx90mm Mount bolts - 175 in/lbs, 14-15 ft/lbs 

    https://avsport.org/acft/WarpDrive/Prop_Manual.pdf

     


    Thank you said by: Andrew Dunning

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