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Thread: AF autopilot not tracking localizers

  1. #1

    AF autopilot not tracking localizers

    I have an AFS3500, AF autopilot, and Garmin 430w all wired together according to Steinair. I recently updated the software on the 3500. This is all installed in an RV7A with about 23 flight hours, still in Phase I testing so I'm learning the aircraft and the instruments at the same time.

    I can fly a GPS/LPV approach with both vertical and lateral autopilot capture. Really nice. The problem comes with localizer and ILS approaches the auto pilot will not capture laterally. The vertical of the ILS works. The 430 map page shows magenta course but no dashed line intercepting it. I also tried going direct to a VOR, green needle, VLOC with autopilot in EFIS mode today, didn't work.

    Secondly, I can not get the heading bug to track a heading in EFIS auto pilot mode using LAT HDG, works with vertical. I get yellow flight director wings.

    The problems could be simple user setup error since I'm still new to this equipment, a configuration issue or wiring error.

    Ideas?
    Last edited by timotb; 06-22-2014 at 07:49 PM.

  2. #2
    Quote Originally Posted by timotb View Post
    I have an AFS3500, AF autopilot, and Garmin 430w all wired together according to Steinair. I recently updated the software on the 3500. This is all installed in an RV7A with about 23 flight hours, still in Phase I testing so I'm learning the aircraft and the instruments at the same time.

    I can fly a GPS/LPV approach with both vertical and lateral autopilot capture. Really nice. The problem comes with localizer and ILS approaches the auto pilot will not capture laterally. The vertical of the ILS works. The 430 map page shows magenta course but no dashed line intercepting it. I also tried going direct to a VOR, green needle, VLOC with autopilot in EFIS mode today, didn't work.

    Secondly, I can not get the heading bug to track a heading in EFIS auto pilot mode using LAT HDG, works with vertical. I get yellow flight director wings.

    The problems could be simple user setup error since I'm still new to this equipment, a configuration issue or wiring error.

    Ideas?
    The first thing you need to do is make the AF-Pilot follow the heading bug and altitude bug, once this is working it should be fairly easy to make it fly the ILS.

    1. Make sure the AF-Pilot ARINC in is really wired to the AF-ARINC module, not directly to the 430W
    2. Make sure the AP Roll Gain in the EFIS is not set to 0, start with .05
    3. When on an ILS make sure you have selected the inbound CRS.
    Rob Hickman
    Advanced Flight Systems Inc.

  3. #3
    I checked the roll gain today and saw it was set to zero, so I increased it to .05 as recommended. Next I took the aircraft up and flew 2 LOC approaches. I can now fly the heading bug and it did capture the localizer after passing through it once. Might adjust the roll gain to .06 or.07? Not sure if this new information makes your first suggestion moot? I did notice after loading and activating the LOC approach vectors to final, a magenta dashed line from current position to localizer was visible on the 430 map, but the aircraft autopilot ignored it, continued to fly the bug. I had to turn the aircraft on the localizer using the heading bug.. Had EFIS LAT and VERT both set to ARM.

    I'm not sure why the inbound CRS selected is required, albeit much easier to fly.

    Since I only few two approaches it's possible this is a simple set up problem.
    Last edited by timotb; 06-27-2014 at 08:26 PM.

  4. #4
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    when selecting an ils approach or localizer approach in the 430w you get gps guidance(magenta) and then it switches to green(ILS or localizer) VLOC . The course needle does not change automatically and you have to set in manually.
    Alan

  5. #5
    Quote Originally Posted by amekler View Post
    when selecting an ils approach or localizer approach in the 430w you get gps guidance(magenta) and then it switches to green(ILS or localizer) VLOC . The course needle does not change automatically and you have to set in manually.
    Alan
    So when flying an ILS (or LOC), leave the 430 in the GPS mode and tune the course to be ready for the automatic switch to VLOC?
    Last edited by timotb; 06-30-2014 at 11:15 AM.

  6. #6
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    Join Date
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    gilford, nh
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    that is one way to do it. you are using the gps for guidance. you cannot dial in the course until it switches to bloc.
    the other way is to switch to bloc dial in the course and fly with the heading bug on the ap lateral nag then once you about to intercept change to ap to later arm or lateral nag.
    what i found is it is a lot easier for the ap to fly llv approaches than ils.

    alan

  7. #7
    Quote Originally Posted by amekler View Post
    that is one way to do it. you are using the gps for guidance. you cannot dial in the course until it switches to bloc.
    the other way is to switch to bloc dial in the course and fly with the heading bug on the ap lateral nag then once you about to intercept change to ap to later arm or lateral nag.
    what i found is it is a lot easier for the ap to fly llv approaches than ils.

    alan
    Thanks Alan, I had ap switched to ARM too early and was expecting the CRS needle to set automatically.

  8. #8
    Thought I had this problem solved. At last post I flew 2 practice VFR ILS and a LOC. The ILS approaches were text book on autopilot. Today I flew same ILS and LOC. The LOC on both were intermittently disappearing and autopilot was taking me off course. Didn't see any red "X" or indication signal was off. Going to try again in a few days and see if I get same results.

  9. #9
    It the NAV signal is going away it can't follow it, It should follow the CRS when the signal is lost.
    Rob Hickman
    Advanced Flight Systems Inc.

  10. #10
    Today flew 2 different ILS and same LOC......everything worked fine. Must have been user error the other day.

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