Narrative:

We picked up the aircraft after it was returned to service for a repeat write up involving ahrs number 2 failing to initialize. We were in tune to making sure that the ahrs operated normally during preflight and it did. During this day we were assigned a series of flights. On the first leg during the climb out both channels of the autopilot and yaw damper (yd) kicked off during the climb out; but they immediately reset without action from the crew and we accepted the fault as spurious and continued without incident. On the second leg we received the autopilot/yaw damper fail messages during the high speed portion of the takeoff roll and again they went away. During the climb out at a high pitch attitude the autopilot start pitching down nose and I disconnected it and again the autopilot/yaw damper fail messages posted for a short time. We decided something was not right and upon arrival we deferred and secured the autopilot and yaw damper systems.[maintenance] asked us to move the airplane to [a maintenance center] to have [maintenance] performed on the autopilot/yaw damper system. During the flight we received a pitch miscompare between the captain's and first officer's attitude displays. The first officer's display was about five degrees higher than the captain's and the standby so it was easy to identify the problem and fly the airplane. As soon as we got to cruise the miscompare went away and did not come back the remainder of the flight.upon arrival at the service center we asked to speak to an avionics technician as these problems seemed related to one another. One came out and we explained all of the things we observed. He took note of that and opened the nose cowl and immediately identified the problem; the number 2 ahrs unit was not secure in its rack and was easily moved with one finger. He said that all of the indications we received were a result of this issue.the ahrs units are not part of our preflight checks; but going forward I will certainly look at them especially when receiving the aircraft from [maintenance] on the ahrs itself. It makes sense that an ahrs unit would not give accurate info if it is not secure in its rack. When we were accelerating clearly the ahrs unit was shifting in its mount and causing different abnormal indications; but when we were in non-accelerated flight the ahrs unit went back into its normal spot leading to normal indications.the captain further discussed the issues with [maintenance] control they decided that the two items were related and no additional info for [maintenance] was needed. Of note; ahrs number 2 was not safety wired and number 1 was.I would suggest reviewing the [maintenance] manual procedures; cessna advised that the aircraft must be leveled after the ahrs units are adjusted and it does not appear that all of the procedures were followed by the previous vendor.

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Original NASA ASRS Text

Title: CE-680 Captain reported experiencing multiple autopilot/yaw damper anomalies that were later traced to the #2 AHRS unit not being properly secured in its rack by the previous maintenance personnel.

Narrative: We picked up the aircraft after it was returned to service for a repeat write up involving AHRS number 2 failing to initialize. We were in tune to making sure that the AHRS operated normally during preflight and it did. During this day we were assigned a series of flights. On the first leg during the climb out both channels of the autopilot and Yaw Damper (YD) kicked off during the climb out; but they immediately reset without action from the crew and we accepted the fault as spurious and continued without incident. On the second leg we received the autopilot/yaw damper fail messages during the high speed portion of the takeoff roll and again they went away. During the climb out at a high pitch attitude the autopilot start pitching down nose and I disconnected it and again the autopilot/yaw damper fail messages posted for a short time. We decided something was not right and upon arrival we deferred and secured the autopilot and yaw damper systems.[Maintenance] asked us to move the airplane to [a maintenance center] to have [maintenance] performed on the autopilot/yaw damper system. During the flight we received a pitch miscompare between the Captain's and First Officer's attitude displays. The First Officer's display was about five degrees higher than the Captain's and the standby so it was easy to identify the problem and fly the airplane. As soon as we got to cruise the miscompare went away and did not come back the remainder of the flight.Upon arrival at the service center we asked to speak to an avionics technician as these problems seemed related to one another. One came out and we explained all of the things we observed. He took note of that and opened the nose cowl and immediately identified the problem; the number 2 AHRS unit was not secure in its rack and was easily moved with one finger. He said that all of the indications we received were a result of this issue.The AHRS units are not part of our preflight checks; but going forward I will certainly look at them especially when receiving the aircraft from [maintenance] on the AHRS itself. It makes sense that an AHRS unit would not give accurate info if it is not secure in its rack. When we were accelerating clearly the AHRS unit was shifting in its mount and causing different abnormal indications; but when we were in non-accelerated flight the AHRS unit went back into its normal spot leading to normal indications.The Captain further discussed the issues with [Maintenance] Control they decided that the two items were related and no additional info for [maintenance] was needed. Of note; AHRS number 2 was not safety wired and number 1 was.I would suggest reviewing the [maintenance] manual procedures; Cessna advised that the aircraft must be leveled after the AHRS units are adjusted and it does not appear that all of the procedures were followed by the previous vendor.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.