The AI in my 1979 231 failed and was replaced with an exchange unit in February of this year. It failed again and was again replaced with an exchange unit in October during the annual. Yesterday on our way home from Alabama it failed again. Just does a very slow roll to 20 degrees right bank. Fortunately I have a backup AV-30 which is spot on and we were for the most part vmc. No anomalies with the vacuum system of which I am aware. Just to make sure, I turned on the backup vacuum pump, but nothing changed.
I called the overhaul facility in Wichita and they are sending a replacement to my maintainer after the new year. Do you fellas find it conceivable that two units in a row could fail like this, or might there be an issue with my airplane that could cause this?
If this happens again I believe I will replace it with an electric AI, but will that be compatible with a Century 41 autopilot?
I welcome your comments and advice.