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Thread: Sb00020

  1. #11
    Senior Member Pilawt's Avatar
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    Default Re: Sb00020

    I just found a PA-18 manual online and it calls for 62 +/-2, even more than the CC11. So my mechanic's recollection was mistaken. In the immortal words of Emily Litella ... "Never mind!"

    Jeff Jacobs
    Vancouver WA / KVUO
    C-172N-180


  2. #12
    Administrator Pete D's Avatar
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    Default Re: Sb00020

    He may have been thinking the ailerons instead of the elevator...

    Pete D

  3. #13
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    Default Re: Sb00020

    This is a good reminder regarding cable tensions. Cable tension is important for two reasons: the first is to provide an adequate flutter margin.The second is to ensure adequate control travel- when cables are slack and then put under load, the surfaces will not deflect as far.

  4. #14
    Senior Member couleeone's Avatar
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    Default Re: Sb00020

    If the torque is still within tolerances as per SB 15 does it still need to be replaced to do SB 20?
    Geo
    Piper Cub J3
    www.cubdriving.com

  5. #15
    Senior Member Pilawt's Avatar
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    Default Re: Sb00020

    Quote Originally Posted by couleeone View Post
    If the torque is still within tolerances as per SB 15 does it still need to be replaced to do SB 20?
    It would appear that it does need to be replaced. Per SB20:

    For aircraft S/N 00001 through 00146:
    1. If the torque tube was replaced while complying with SB00015 then proceed directly to the section for all aircraft.
    2. If the torque tube was not replaced previously then replace the torque tube per SB00015 before going to the section for all aircraft.
    Last edited by Pilawt; 02-26-2012 at 05:42 PM.
    Jeff Jacobs
    Vancouver WA / KVUO
    C-172N-180


  6. #16
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    Default Re: Sb00020

    Quote Originally Posted by Pilawt View Post
    It would appear that it does need to be replaced. Per SB20:

    For aircraft S/N 00001 through 00146:
    1. If the torque tube was replaced while complying with SB00015 then proceed directly to the section for all aircraft.
    2. If the torque tube was not replaced previously then replace the torque tube per SB00015 before going to the section for all aircraft.
    I was interpreting it the other way, that if I complied with SB15 previously and didn't replace torque tube then in SB 20 it says if the torque tube was not previously replaced then replace it before complying with SB 20..........maybe someone from CC can weigh in and clear it up. My A&P also read it this way.
    Jon

  7. #17
    Senior Member turbopilot's Avatar
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    Default Re: Sb00020

    Quote Originally Posted by txcub View Post
    I was interpreting it the other way, that if I complied with SB15 previously and didn't replace torque tube then in SB 20 it says if the torque tube was not previously replaced then replace it before complying with SB 20..........maybe someone from CC can weigh in and clear it up. My A&P also read it this way.
    Jon
    The whole SB15/20 saga needs some more detail. Why mandatory within 10 hours? Have there been failures? I thought the issue with SB15 was loose rivets between the torque tube and the mast. Yet SB15 torque tube replacement involves replacing the existing torque tube with a tube having a thicker wall. As far as I can see the rivet attachment to the torque tube remains the same. So how does this fix the problem? Looks like it can happen again.
    Bob Anderson, CC11-00435, N94RA

  8. #18
    Senior Member Pilawt's Avatar
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    Default Re: Sb00020

    Quote Originally Posted by txcub View Post
    I was interpreting it the other way, that if I complied with SB15 previously and didn't replace torque tube then in SB 20 it says if the torque tube was not previously replaced then replace it before complying with SB 20..........maybe someone from CC can weigh in and clear it up. My A&P also read it this way.
    Jon
    That's what I said (or meant to say, anyway) -- if the torque tube wasn't replaced for SB15, SB20 requires that it be replaced now, regardless of its condition.
    Jeff Jacobs
    Vancouver WA / KVUO
    C-172N-180


  9. #19
    Administrator Pete D's Avatar
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    Default Re: Sb00020

    Quote Originally Posted by couleeone View Post
    If the torque is still within tolerances as per SB 15 does it still need to be replaced to do SB 20?
    Yes. If it was not replaced as part of SB 15 then it will need to be replaced if the S/N is in the range called out for SB 15. The replacement torque tube (and aircraft built after SB 15) is a thicker walled torque tube.

    There have been no failures. Turbopilot, you are partially correct. SB 15 came about due to some torque tubes having loose rivets. The torque tube part of SB 20 is intended to make sure that all aircraft end up with the heavy duty torque tube regardless of whether the rivets are loose or not.
    Pete Dougherty
    Customer Support Manager
    Cub Crafters Inc

  10. #20
    Senior Member turbopilot's Avatar
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    Default Re: Sb00020

    Quote Originally Posted by Pete D View Post
    Yes. If it was not replaced as part of SB 15 then it will need to be replaced if the S/N is in the range called out for SB 15. The replacement torque tube (and aircraft built after SB 15) is a thicker walled torque tube.

    There have been no failures. Turbopilot, you are partially correct. SB 15 came about due to some torque tubes having loose rivets. The torque tube part of SB 20 is intended to make sure that all aircraft end up with the heavy duty torque tube regardless of whether the rivets are loose or not.
    Thanks Pete. So the need for a heavier torque tube comes from some other decision on structural analysis and the caution about loose sticks as per SB15, still applies? What I am trying to understand is whether the torque tube wall thickness is some how related to loose sticks or was the inclusion to replace the torque tube in SB15 because the rivet holes became elongated in the original torque tube?
    Last edited by turbopilot; 02-27-2012 at 09:47 AM.
    Bob Anderson, CC11-00435, N94RA

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