Century 41 Problems

[zehutiman]

I’m a new owner of a M20J Missile that uses a Century 41 AP.  I’ve had about 6 flights in the airplane and the AP has given me some problems.  It’s simply inconsistent in its performance.  Most of the time, it works well, but just yesterday, for instance, after 20 minutes of straight and level, the altitude began creeping up very slowly — 75 fpm.  Then, 5 minutes later, it commanded a descent, from which I had to disconnect the AP…I’m talking about 1500 fpm.  The uncommanded inputs occurred with “ALT” selected.  Voltage on the airplane seems ok — 13.6v.  Any ideas what could be wrong?  Do I need to upgrade?  
 

[Fly Boomer]

3 minutes ago, zehutiman said:

I’m a new owner of a M20J Missile that uses a Century 41 AP.  I’ve had about 6 flights in the airplane and the AP has given me some problems.  It’s simply inconsistent in its performance.  Most of the time, it works well, but just yesterday, for instance, after 20 minutes of straight and level, the altitude began creeping up very slowly — 75 fpm.  Then, 5 minutes later, it commanded a descent, from which I had to disconnect the AP…I’m talking about 1500 fpm.  The uncommanded inputs occurred with “ALT” selected.  Voltage on the airplane seems ok — 13.6v.  Any ideas what could be wrong?  Do I need to upgrade?  
 

You will no doubt get many recommendations to replace it with a GFC-500, but I would contact @Jake@BevanAviation.  He is our resident autopilot guy, and always seems to know what to do.

[Jake@BevanAviation]

Unfortunately, with the current state of Century Flight Systems getting a Century 41 fully operational and reliable might be a big issue.  A lot of the parts are no longer available for this system.  Century is no longer doing repairs at the factory to my knowledge and has very limited support.  Due to this reason I stopped working on the C41 years ago and would only send the system back to the factory for repair.  The last system I sent in years ago came back with a 9K estimate for repair. 

My recommendation would be to replace it when you can for better reliability and support with a newer modern AP system like Garmin.  There still might be some shops out there trying to do bench repairs but parts will be the biggest limitation. Altitude transducer problems were not uncommon for this system.

[zehutiman]

1 hour ago, Jake@BevanAviation said:

Unfortunately, with the current state of Century Flight Systems getting a Century 41 fully operational and reliable might be a big issue.  A lot of the parts are no longer available for this system.  Century is no longer doing repairs at the factory to my knowledge and has very limited support.  Due to this reason I stopped working on the C41 years ago and would only send the system back to the factory for repair.  The last system I sent in years ago came back with a 9K estimate for repair. 

My recommendation would be to replace it when you can for better reliability and support with a newer modern AP system like Garmin.  There still might be some shops out there trying to do bench repairs but parts will be the biggest limitation. Altitude transducer problems were not uncommon for this system.

Excellent info…thx.  Yeah, for that much money, I might as well begin looking at upgrade alternatives.  
 

[Joe Linnebur]

I’m not sure what your avionics package is, but we had a similar issue with ours and the fix was a rebuilt attitude indicator (basic ai, not a glass). Explanation was we had some bearings going bad, resulted in a slow drift from level. Just another path for you to look down.

[zehutiman]

6 hours ago, Joe Linnebur said:

I’m not sure what your avionics package is, but we had a similar issue with ours and the fix was a rebuilt attitude indicator (basic ai, not a glass). Explanation was we had some bearings going bad, resulted in a slow drift from level. Just another path for you to look down.

Thanks.