Narrative:

Received stab trim [and] mach trim caution messages as both systems disconnected as we rotated and raised gear after takeoff. There was prior history of this issue with this aircraft. I was pilot flying (PF) and asked my first officer (first officer) to re-engage the stab and mach trim. We continued the climb out and on course when the stab and mach trim disconnected again with 'autopilot trim is nd' and 'ap pitch trim' caution messages. My first officer ran QRH for stab and mach trim and re-engaged both systems again. As we were leveling at 10;000 feet we noticed alts caps but the aircraft kept climbing through 10;000. I disengaged the autopilot and we experienced a violent nose down drop of about 200 to 300 feet and heard a loud bang as the autopilot disengaged. I was able to regain control and level the aircraft and re-trim the pitch. We notified ATC and asked for a block altitude while we troubleshot a flight control issue. We notified dispatch and [maintenance] via ACARS and we agreed that returning to [departure airport] was the best and safest course of action. I notified our flight attendant and made a PA to the passengers advising them of the issue. I was able to re-engage the autopilot and handed the controls over to the first officer where he became the PF. I [advised] ATC and we were vectored back. We landed with no further issues and there were no known issues from any passengers. We switched aircraft and continued on 45 minutes after arriving at the gate. Aircraft with a known stab trim or stab motor issues should have a functional test flight before being returned to passenger service. This was quite a disturbing event and could have been much worse.

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Original NASA ASRS Text

Title: CRJ-200 Captain reported returning to departure airport after experiencing stabilizer trim anomalies.

Narrative: Received Stab Trim [and] Mach Trim caution messages as both systems disconnected as we rotated and raised gear after takeoff. There was prior history of this issue with this aircraft. I was Pilot Flying (PF) and asked my First Officer (FO) to re-engage the Stab and Mach Trim. We continued the climb out and on course when the Stab and Mach Trim disconnected again with 'Autopilot Trim is ND' and 'AP Pitch Trim' caution messages. My FO ran QRH for Stab and Mach Trim and re-engaged both systems again. As we were leveling at 10;000 feet we noticed Alts Caps but the aircraft kept climbing through 10;000. I disengaged the autopilot and we experienced a violent nose down drop of about 200 to 300 feet and heard a loud bang as the autopilot disengaged. I was able to regain control and level the aircraft and re-trim the pitch. We notified ATC and asked for a block altitude while we troubleshot a flight control issue. We notified Dispatch and [Maintenance] via ACARS and we agreed that returning to [departure airport] was the best and safest course of action. I notified our Flight Attendant and made a PA to the passengers advising them of the issue. I was able to re-engage the autopilot and handed the controls over to the FO where he became the PF. I [advised] ATC and we were vectored back. We landed with no further issues and there were no known issues from any passengers. We switched aircraft and continued on 45 minutes after arriving at the gate. Aircraft with a known Stab Trim or Stab motor issues should have a functional test flight before being returned to passenger service. This was quite a disturbing event and could have been much worse.

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.