S-Tec 20 issues

Discussion in 'Avionics and Upgrades' started by Eric Brunelle, Mar 10, 2019.

  1. Eric Brunelle

    Eric Brunelle Filing Flight Plan

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    Hello All - Yesterday my S-Tec 20 started behaving badly. I set the heading bug and shortly after, my Archer turned left away from the bug. I changed the imput to my 430, and the AP started wandering back and forth a few degrees - always over correcting. It put me in a gentle side to side sway - OK for slow dancing, but no fun in the air. The steering control knob seems to work OK. Hopefully more tests tomorrow if the weather holds. Any ideas?
    Thanks, EricB
     
  2. Jesse Saint

    Jesse Saint Pre-takeoff checklist

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    The STEC uses the gyro in the Turn & Bank for stability, usually. My guess would be that your T&B is failing.
     
  3. TAMPA TED

    TAMPA TED Filing Flight Plan

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    Need a repair manual for an S-Tec 20/30.....just to borrow or download
     
  4. Eric Brunelle

    Eric Brunelle Filing Flight Plan

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    I have one - got it from a guy on the Piper Forum. PM me your email and I will send it to you.
     
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  5. flyingron

    flyingron Touchdown! Greaser!

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    First off, I've found S-TEC (or whatever they call themselves these days) phone support to be pretty good if you have questions like these.

    Note, manual or not, you're not supposed to be working on autopilots as a non-AP PERIOD.
     
  6. TAMPA TED

    TAMPA TED Filing Flight Plan

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  7. TAMPA TED

    TAMPA TED Filing Flight Plan

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    Thank you Eric
     
  8. TAMPA TED

    TAMPA TED Filing Flight Plan

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    How about an avionics IA???
     
  9. flyingron

    flyingron Touchdown! Greaser!

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    An IA ***IS*** an A&P. Nothing changes what I said.
     
  10. bflynn

    bflynn En-Route

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    How about experimental? Database updates? Dusting and cleaning the exterior case?
     
  11. flyingron

    flyingron Touchdown! Greaser!

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    Do you have something better to do than be a forum troll? The Archer Is **NOT** an experimental.
     
  12. bkspero

    bkspero Pre-takeoff checklist

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    When I bought my plane its Century IIB over corrected and produced a side to side sway. I was advised that the roll (actually the only) servo could be sticky and requiring to much torque to start and reverse motion. That extra torque would cause it to overshoot the desired heading and over correct. The first try at a solution was to exercise the servo full left and then full right about 30 times using the manual control knob (in an effort to smooth out its motion). That worked for me. I exercise it a few times every runup and its been working properly for 7 years.

    I recognize that they are different autopilots, but both use roll servos and could, I expect, share the same cause for similar symptoms.
     
  13. Eric Brunelle

    Eric Brunelle Filing Flight Plan

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    I'm going to try that. If that doesn't do it, then over to the avionics shop. I'm not messing with any of the innerds.

    It's actually been a good experience - not having the AP available. I think we can become too dependent on them, and that can erode the IFR skills.
     
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  14. Jim_CAK

    Jim_CAK Pre-takeoff checklist PoA Supporter

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    Good tip. We have an S-Tec that is overshooting. I will give that a try.
     
  15. TAMPA TED

    TAMPA TED Filing Flight Plan

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