AP issue or 430 Issue

[GaryP1007]

I have a KAP 150 AP.  When I try to use "Nav" or "Aprch" (linked to 430) the airplane drifts 1-2 dots to the left.  Is this a tuning issue with the 430 or an AP issue?  All opinions welcome!

[PTK]

Does it work normally in heading mode?

[OR75]

the AP should be picking the signal from the indicator (I am thinking it is a G-106) and not directly from the GNS-430 unit.

[carusoam]

KAP100 experience....

Check wich radio source is supplying the guidance.  GPS should give solid, on the line guidance.  VORs don't work as well, especially close in to the station with signal variations....

Compare your two sources if you can.

Do you have a switch for GPS vs VOR source?  Sorry, I have slightly older BK technology...

Blue light on for GPS signal....  Blue light off for VOR signal...

Otherwise allow it to settle on a solution.  Mine seems to behave like an old computer.  It's slow to react and behave properly, but after a couple minutes, it improves it's tracking skills.

 

As OR75 indicates, the AP guidance comes from the HSI.  Verify what is feeding the HSI...

best regards,

-a-

[FlyDave]

You may be able to adjust this issue out by setting the CDI scale manualy.

On the AUX pages, look for CDI/Alarms and select it. On that page you can change it from "Auto" to "Manual". Setting it to "Manual" and selecting a lower number may resolve the issue. If you have the 430 pilots guide (PDF) look on page 172 for this process.

I have a KFC-200 and 430 Non-WAAS and have experienced this issue as well. Changing the CDI scale has corrected it. I'm not sure if this will have the same effect on a WAAS unit.

Best of luck and let us know when you get it resolved.

[jetdriven]

On the Century IIB, setting the nav mode selector to LOC increases the sensitivity. That and changing the CDI scale to 2 NM now the autopilot stays within .15 NM of centerline

 

[Seth]

I had a similar issue with the KFC 200 in my Mooney Missile upon delivery.  It tracked a dot or two to the left.  It was an autopilot issue and after two small adjustments, the AP now tracks perfectly.

On level ground, with the aircraft on, engage the autopilot and feel if the AP is pushing the plane left right up or down while slightly pushing on the controls.  Mine was pushing ever so slightly to the left and down.  No joke, this "allignment" was conducted by a pro (he was really good) by turning two screws in the AP module to properly callibrate the system.  These screws are used to calibrate the system to "zero."  The AP though tracking was pushing ever so slightly to the left and was fighting itself the whole time and thus correcting itself the entire time to get back on course prior to the adjustment.  The natural location ended up being about a dot or two off ot the left.

It sounds similar, but it's a different AP, so I'm not sure.  The shop that fixed it is in MN, but I'm sure there's a good shop around you.  I'll get the name and contact information to you in the next week or so when I look for the paperwork and PM you.

Take care,

-Seth

[GaryP1007]

Quote: allsmiles

Does it work normally in heading mode?

[OR75]

Does it eventually correct or does it stay offset 2 dots ?

[DaV8or]

Don't know about the King system, but my S-Tec always tracked a little left of the centerline. In track mode it was two dots off and in GPSS mode (Heading), it was about half dot off. It turns out it's an A/P adjustment that is just a turn of a screwdriver. Had it done today, will test this weekend.

[GaryP1007]

Quote: OR75

Does it eventually correct or does it stay offset 2 dots ?

[OR75]

APs usually have inputs from the DG / AI and VOR/LOC indicator (not sure how the KAP150 is wired). I am thinking one of these needs to be checked

[jlunseth]

Quote: GaryP1007

It does not correct, it only gets worse...drifting further and further.

[GaryP1007]

Quote: jlunseth

It does not correct, it only gets worse...drifting further and further.

[jlunseth]

When you say it starts two dots off and gets worse, it sounds as though the 430 is not actually communicating with the DG.  Sounds like the plane is just drifting, and may start to the right on a regular basis simply because there is more weight over there for some reason (although normally it is the other way around), that is, the plane is doing a shallow right bank and is uncontrolled.

[OR75]

A bit difficult to troubleshoot like this.

Has the system ever worked  (or just been wired) ?

Is your indicator (GI-106 ??) working properly ? (is the drift indication on the 1st page of the GNS430 coherent with the GI-106 drift indication) ?

 

 

[N601RX]

Quote: GaryP1007

I have a KAP 150 AP.  When I try to use "Nav" or "Aprch" (linked to 430) the airplane drifts 1-2 dots to the left.  Is this a tuning issue with the 430 or an AP issue?  All opinions welcome!