I have a century 21 autopilot coupled to Garmin 530W and KX155 as nav1/2. I don't have a HSI but just a DG with heading bug.
It does hold the heading perfectly. But in the Nav mode it's unreliable. Say in NAV mode if CDI is to right and the heading bug is moved to left then the plane still wants to turn left Instead of following CDI. But if I put heading bug within 10 degree of DKT then it tracks the magenta line good.
So it seems like it could be user issue instead of autopilot so I am looking for a service manual to understand it better. I do have the user manual which doesn't help much.
I understand if in Nav mode some flag signal is messed up then autopilot wouldn't follow CDI but how does GPS provide flag information in non CDI mode. Nav 1/2 switch through some relay I believe. It's not the switch for sure because I tried to set both radio CDI in opposite deviation and set heading but straight ahead so switching between both Nav made plane wants to turn towards corresponding CDI. Just having issues making it follow magenta line or CDI regardless of heading bug.
Is there a possibility and if so why that Nav mode would depend on heading bug in a non HSI setup?
View attachment ImageUploadedByPiper Forum1449870598.748468.jpg
It does hold the heading perfectly. But in the Nav mode it's unreliable. Say in NAV mode if CDI is to right and the heading bug is moved to left then the plane still wants to turn left Instead of following CDI. But if I put heading bug within 10 degree of DKT then it tracks the magenta line good.
So it seems like it could be user issue instead of autopilot so I am looking for a service manual to understand it better. I do have the user manual which doesn't help much.
I understand if in Nav mode some flag signal is messed up then autopilot wouldn't follow CDI but how does GPS provide flag information in non CDI mode. Nav 1/2 switch through some relay I believe. It's not the switch for sure because I tried to set both radio CDI in opposite deviation and set heading but straight ahead so switching between both Nav made plane wants to turn towards corresponding CDI. Just having issues making it follow magenta line or CDI regardless of heading bug.
Is there a possibility and if so why that Nav mode would depend on heading bug in a non HSI setup?
View attachment ImageUploadedByPiper Forum1449870598.748468.jpg
