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Thread: Altitude loss in a turn

  1. #31
    If you have the EFIS ALT gain set to 9 you should see this:

    V Speed = 9 x 40 FT

    V Speed = 360 Ft/Min

    Double check the EFIS ALT gain, I don't think it could possibly stay at 40FT low with an EFIS ALT Gain of 5 or more.
    Rob Hickman
    Advanced Flight Systems Inc.

  2. #32
    Senior Member
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    ok will check on my next flight
    should i reset EFIS ALT GAIN to 5?
    Alan

  3. #33
    A year ago now I send my servos in for the upgraded safety nut on the main arm. The safety nut replaced the original screw. I installed the servo and all seemed well. During the summer, and an upgrade from an ADI II to the new EFFIS driven autopilot I experienced a lot of small roll issues. One of the problems that I experienced was that in turns the autopilot had trouble holding altitude. I chased this issue ALL summer, numerous tests, numerous settings, and it seemed to get worse until it failed. When describing the problem to Lucas he told me that they had had a manufacturing issue last winter in some of the upgraded servos. I would not have thought that the altitude control would be affected by the roll servo but it most definitely was. I have not had any altitude issues in turns since the roll servo was repaired.
    It would have been nice if the company had sent out an email to those whose servos may have been affected. This would have saved me hours of testing and also saved one ILS approach that went south on me when the system did not hold course or altitude on a turn to final in IMC conditions.

  4. #34
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    tom,
    interesting. my servos are from 2009. i replaced the safety nut about 3 years ago.maybe i should replace my roll servo.
    Lucas what do you sugest?
    Alan

  5. #35
    Alan, your servos are most likely fine. Tom's servo was serviced in early 2012. His problem in the servo was caused by a broken roll pin inside the gear box. We identified an improperly sized hole in the servo shaft which allowed the roll pin to break. Unfortunately there is no way to track the individual servo shafts that are installed. The supplier has been changed since that time.

    How much altitude is being lost in a turn?
    Lucas
    Trutrak Tech Support

  6. #36
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    100 feet.
    alan

  7. #37
    What is your GPSS gain setting?
    Lucas
    Trutrak Tech Support

  8. #38
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    The loss seems mostly when in heading mode on the efis and i turn 90 degrees or more.
    Alan

  9. #39
    Senior Member
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    Mar 2010
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    gilford, nh
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    flew today in smooth air. Altitude read about 20-30 feet low with EFIS ALT gain set to 10. This was better than with it set to 5.
    What I didn't like was in descents I would bust through the altitude set by 80-100 feet before slowly correcting .
    Alan

  10. #40
    ALT Gain of 10 is way to high, It should be hunting up and down like mad with a gain of 10?

    V_SPEED = 10 (gain) x 20 FT

    = 200 Ft/min commanded climb rate

    Was it showing a 200 FT/min commanded climb on the check list page?

    Are you adjusting this on the screen that is wired to the ARINC module?
    Rob Hickman
    Advanced Flight Systems Inc.

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