I wanted to get the word out about this important autopilot panel service bulletin.
I have skyview system with an autopilot control panel. Yesterday my elevator trim became flakey, possibly making un-commanded trim movements, but certainly not reliably making manually commanded movements. Eventually I was able to bring it back to about 2/3 of the way to the down limit, so the stick was heavy but still manageable. Manual control became more and more intermittent and then stopped working in one direction entirely.
The autopilot panel was clearly receiving trim commands in both directions, but the actuator would only move in one direction. Neither pilot or copilot stick trim buttons or the autopilot itself could move the trim in the broken (up) direction. After several minutes of dinking with it, I pulled the fuse to make sure the trim did not completely runaway to the down limit.
in fairness, I don’t know if the AP panel had run the trim to the down limit as a part of it failing…or if the autopilot had run the trim to the down limit since it was dealing with some significant vertical drafts before I kicked it off.
Once on the ground, I started diagnosing and found the actuator was fine and if I physically reversed the actuator drive polarity the problem reversed. So the fault had to be somewhere in the signal from the Dynon system. When moving the actuator in the “working” direction the AP panel was sending a full command signal to the actuator, but in the ”broken” direction it was only sending a signal in the mV range.
Then I started hunting and happened across this service bulletin on the AP panel where the AP panel can cause un-commanded trim movements or completely fail in one or both directions. Since my serial number was among those affected, I pulled the unit and FedEXed it back to Dynon for repair and am grounded in the meantime.
I have to say that I am extremely disappointed Dynon did not proactively contact owners about a potential runway trim caused by a failure in the AP panel. When I called Dynon technical support, given my phone number they already had the rest of my contact information and mailing address. They know what my system is and the serial numbers of each sub-system yet, as far as I know, I never received a heads up about this potentially catastrophic issue.
Hopefully I will receive the repaired AP panel back and will never see this problem again, but a tremendous amount of trust has been lost in the hardware and in Dynon.
I have skyview system with an autopilot control panel. Yesterday my elevator trim became flakey, possibly making un-commanded trim movements, but certainly not reliably making manually commanded movements. Eventually I was able to bring it back to about 2/3 of the way to the down limit, so the stick was heavy but still manageable. Manual control became more and more intermittent and then stopped working in one direction entirely.
The autopilot panel was clearly receiving trim commands in both directions, but the actuator would only move in one direction. Neither pilot or copilot stick trim buttons or the autopilot itself could move the trim in the broken (up) direction. After several minutes of dinking with it, I pulled the fuse to make sure the trim did not completely runaway to the down limit.
in fairness, I don’t know if the AP panel had run the trim to the down limit as a part of it failing…or if the autopilot had run the trim to the down limit since it was dealing with some significant vertical drafts before I kicked it off.
Once on the ground, I started diagnosing and found the actuator was fine and if I physically reversed the actuator drive polarity the problem reversed. So the fault had to be somewhere in the signal from the Dynon system. When moving the actuator in the “working” direction the AP panel was sending a full command signal to the actuator, but in the ”broken” direction it was only sending a signal in the mV range.
Then I started hunting and happened across this service bulletin on the AP panel where the AP panel can cause un-commanded trim movements or completely fail in one or both directions. Since my serial number was among those affected, I pulled the unit and FedEXed it back to Dynon for repair and am grounded in the meantime.
I have to say that I am extremely disappointed Dynon did not proactively contact owners about a potential runway trim caused by a failure in the AP panel. When I called Dynon technical support, given my phone number they already had the rest of my contact information and mailing address. They know what my system is and the serial numbers of each sub-system yet, as far as I know, I never received a heads up about this potentially catastrophic issue.
Hopefully I will receive the repaired AP panel back and will never see this problem again, but a tremendous amount of trust has been lost in the hardware and in Dynon.
