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Autocontrol IIIB
I have the original Autocontrol IIIB in my 79 Archer. Lately it has been flying one dot to the right of course when in GPS/NAV mode. I've set the CDI scale to 1.0nm full scale on the GPS so the error is only about 0.2 nm. If I set the heading but to the right a little, we fly right down the line. This says to me that the autopilot is putting out a small bias to the left that the GPS/NAV has to constantly correct. Is there a simple adjustment in the autopilot to correct this? Maybe I should just vent to the newsgroup and leave good enough alone! Chuck |
#2
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In article ,
PaulaJay1 wrote: I have the original Autocontrol IIIB in my 79 Archer. Lately it has been flying one dot to the right of course when in GPS/NAV mode. Wild guess: Is your rudder trim set right? -- Ben Jackson http://www.ben.com/ |
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#6
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In article , "James M. Knox"
writes: . Maybe I should just vent to the newsgroup and leave good enough alone! That's all it's off! Heck, you may have one of the best units out there! G Like I said, "Maybe I should leave good enough alone." :-) |
#7
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In article , "James M. Knox"
writes: The only IIIB adjustment for "centering" is probably not relevant. Set the IIIB in HDG mode (no NAV tracking). Does it track with the DG heading bug under the lubber line? If so, it's adjusted properly. Interesting. I've not looked at the heading bug tracking that closely. I'll look next time and see if the heading but is on the lubber line or off to the right a little. Chuck |
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#9
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(Michael) wrote in
om: (PaulaJay1) wrote If you have a burning desire to fix this, there is an adjustment on your nav converter (the box that has the multiposition switch with labels like Omni, Loc, Loc Rev, Hdg, and Nav). Personally, I wouldn't mess with it. There's left and right intercept (R13 and R20), plus radio gain. I don't think any of those would affect the situation he is seeing (since it is consistent, not wandering around within a window). There are two more that are only internally adjustable, mostly setting the hysterisis. But since he doesn't have an alignment rig... ----------------------------------------------- James M. Knox TriSoft ph 512-385-0316 1109-A Shady Lane fax 512-366-4331 Austin, Tx 78721 ----------------------------------------------- |
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"Michael" wrote in message om... If you have a burning desire to fix this, there is an adjustment on your nav converter (the box that has the multiposition switch with labels like Omni, Loc, Loc Rev, Hdg, and Nav). Personally, I wouldn't mess with it. If this a/p is anything like the one I had in my prior PA-28, and my current PA-24 before I installed the Stec system, the adjustments I remember are behind the faceplate on the a/p head, not at the coupler. There are two variants of this system, and there will be either 3 or 4 adjustment screws behind that faceplate, depending on whether it has the push-button switches or the rocker type switches. As I recall (and my recall is a little fuzzy), two of them are left and right roll limit adjustments, one sets heading center, and I think the fourth was for sensitivity of some kind. It's been a long time. I used to be anal about getting them set right, and I kept a set of jeweler's screwdrivers in the glove box to use in flight whenever I got bored. |
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