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Cylinder Reassembly Question

in 912 / 914 Technical Questions 7 years ago
Hi Guys,

I am having to replace the oil return tube and pushrod on one of my cylinders.
I followed the procedure in the HMM and have reassembled the cylinder to the engine.

Question 1: Do you have to prime the pushrod?
Question 2: Also is an oil purge necessary?
Question 3: I torqued the cylinders using the new torque method and when I went to the + 150 degrees and released the tension on the torque wrench, the nuts would unwind a small amount, like the stud was preloading, is this normal?

Thanks for your help,
Dan

  • Re: Cylinder Reassembly Question

    by » 7 years ago

    The Hydraulic Valve Tappets will refill themselves as soon as the engine starts.
    You may hear some chattering at first start. It should quiet up within 30 seconds.

    If you have not opened the oil hose between the Oil Tank and the Oil Pump, a purge is not needed.
    Hand Prop the engine before the first start until it registers some oil pressure.
    If you have replaced the oil filter, this might require 50 or more turns.

    The 912 heads are tightened in two stages.
    They are first Pre-Loaded to 90 in-lbs.
    And then "Torqued to Yield" by rotating them another 120°. (Not 150°)

    Are you sure you have installed the Washers under the Flange Nuts?
    Without the washers, you may be running out of thread and are twisting the stud instead of rotating the Nut.

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

      
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  • Re: Cylinder Reassembly Question

    by » 7 years ago

    Hi Bill,

    Thank you for your response.

    This is the new style case and requires the new torque method from the video on this site.

    1st torque to 90 inlbs
    2nd torque to 265 inlbs
    Follow the pattern
    Then one at a time loosen each nut 360 degrees
    Then torque to 90 inlbs
    Then an additional 150 degrees not 120

    I confirmed this with Ronnie from South Mississippi Light Aircraft and he said the unloading was normal.

    Thanks again!
    Dan
    Thank you said by: Wayne Fowler
      
    Report

  • Re: Cylinder Reassembly Question

    by » 7 years ago

    Good to know!
    It looks like the flat washers were also eliminated.
    I hope they update the Heavy Maintenance Manuals soon as it is easy to miss the service instruction and video.

    Ref:
    The Service Instruction...
    https://legacy.rotaxowner.com/si_tb_info/serviceinfo/si-912-025.pdf

    The video...
    https://www.rotax-owner.com/en/videos-topmenu/expanded-video-instructions/463-new-torque

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

    Thank you said by: Capt. Siva,
      
    Report
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