Narrative:

After leveling off at FL370; noticed that the autoplt made a pitching moment up off altitude then recovered. Continued cruise flight. Further into the flight; noticed that the aircraft was mistrimmed; ie; the brick was not centered. It took 1.5 units to the right to bring the aircraft back to coordinated flight. Flight crew felt this was not normal and contacted maintenance control. We were instructed to disengage the autoplt and retrim the aircraft; but that led to uncoordinated flight so we returned the controls to the previous position. We decided it would be the cautious thing to do to set down in ZZZ1 and have the aircraft checked out. A short time later; we received an autoplt mistrim caution; so according to the checklist; we were to disconnect the autoplt and retrim. Upon doing this; the aircraft entered uncontrolled flight; banking to the left and right beyond normal limits. At this point; we decided to land in ZZZ because it was the closest airport with suitable facilities. Landed without further incident; no apparent aircraft damage; no passenger injuries. Followed company procedures to the best of our abilities during this emergency situation.supplemental information from acn 684044: soon after that; the captain disengaged the autoplt. The aircraft immediately snap rolled to the left about 40 to 50 degrees and dove. While he fought to control the aircraft; we went through a series of violent oscillations to the right and left during the next 10-15 seconds. When he regained control of the aircraft; we knew we had to land at the nearest suitable runway. I told center we were having a flight control problem and needed to land at the nearest airport with 7000 ft of runway. I also asked for a vector to that airport. Center vectored us to ZZZ; which was about 40 miles to the west of our position. The captain made several descending circles to the left to lose altitude. I reprogrammed the FMS; got out the approach plates for ZZZ and coordinated with center and approach. We shot the ILS and landed without incident. The next day we were told by the maintenance crew that the flight control problem that we had had was due to an autoplt aileron servo which was progressively turning the aircraft to the right. We were instructed several times that we were not to engage the autoplt on the ferry flight back. I hand flew the aircraft for the entire flight without any problem. I did notice that the aircraft needed some excess right aileron trim; which I discussed with the captain and the maintenance crew onboard. Everything else was normal.

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Original NASA ASRS Text

Title: A CRJ-700 INITIALLY HAD AN UNCOMMANDED PITCH MOVEMENT FOLLOWED LATER BY AN OUT OF TRIM CONDITION LEADING TO UNCTLED L AND R BANKING. AN EMER WAS DECLARED AND FLT DIVERTED TO A NEARBY ARPT.

Narrative: AFTER LEVELING OFF AT FL370; NOTICED THAT THE AUTOPLT MADE A PITCHING MOMENT UP OFF ALT THEN RECOVERED. CONTINUED CRUISE FLT. FURTHER INTO THE FLT; NOTICED THAT THE ACFT WAS MISTRIMMED; IE; THE BRICK WAS NOT CENTERED. IT TOOK 1.5 UNITS TO THE R TO BRING THE ACFT BACK TO COORDINATED FLT. FLT CREW FELT THIS WAS NOT NORMAL AND CONTACTED MAINT CTL. WE WERE INSTRUCTED TO DISENGAGE THE AUTOPLT AND RETRIM THE ACFT; BUT THAT LED TO UNCOORDINATED FLT SO WE RETURNED THE CTLS TO THE PREVIOUS POSITION. WE DECIDED IT WOULD BE THE CAUTIOUS THING TO DO TO SET DOWN IN ZZZ1 AND HAVE THE ACFT CHKED OUT. A SHORT TIME LATER; WE RECEIVED AN AUTOPLT MISTRIM CAUTION; SO ACCORDING TO THE CHKLIST; WE WERE TO DISCONNECT THE AUTOPLT AND RETRIM. UPON DOING THIS; THE ACFT ENTERED UNCTLED FLT; BANKING TO THE L AND R BEYOND NORMAL LIMITS. AT THIS POINT; WE DECIDED TO LAND IN ZZZ BECAUSE IT WAS THE CLOSEST ARPT WITH SUITABLE FACILITIES. LANDED WITHOUT FURTHER INCIDENT; NO APPARENT ACFT DAMAGE; NO PAX INJURIES. FOLLOWED COMPANY PROCS TO THE BEST OF OUR ABILITIES DURING THIS EMER SITUATION.SUPPLEMENTAL INFO FROM ACN 684044: SOON AFTER THAT; THE CAPT DISENGAGED THE AUTOPLT. THE ACFT IMMEDIATELY SNAP ROLLED TO THE L ABOUT 40 TO 50 DEGS AND DOVE. WHILE HE FOUGHT TO CTL THE ACFT; WE WENT THROUGH A SERIES OF VIOLENT OSCILLATIONS TO THE R AND L DURING THE NEXT 10-15 SECONDS. WHEN HE REGAINED CTL OF THE ACFT; WE KNEW WE HAD TO LAND AT THE NEAREST SUITABLE RWY. I TOLD CTR WE WERE HAVING A FLT CTL PROBLEM AND NEEDED TO LAND AT THE NEAREST ARPT WITH 7000 FT OF RWY. I ALSO ASKED FOR A VECTOR TO THAT ARPT. CTR VECTORED US TO ZZZ; WHICH WAS ABOUT 40 MILES TO THE W OF OUR POSITION. THE CAPT MADE SEVERAL DSNDING CIRCLES TO THE L TO LOSE ALT. I REPROGRAMMED THE FMS; GOT OUT THE APCH PLATES FOR ZZZ AND COORDINATED WITH CTR AND APCH. WE SHOT THE ILS AND LANDED WITHOUT INCIDENT. THE NEXT DAY WE WERE TOLD BY THE MAINT CREW THAT THE FLT CTL PROBLEM THAT WE HAD HAD WAS DUE TO AN AUTOPLT AILERON SERVO WHICH WAS PROGRESSIVELY TURNING THE ACFT TO THE R. WE WERE INSTRUCTED SEVERAL TIMES THAT WE WERE NOT TO ENGAGE THE AUTOPLT ON THE FERRY FLT BACK. I HAND FLEW THE ACFT FOR THE ENTIRE FLT WITHOUT ANY PROBLEM. I DID NOTICE THAT THE ACFT NEEDED SOME EXCESS R AILERON TRIM; WHICH I DISCUSSED WITH THE CAPT AND THE MAINT CREW ONBOARD. EVERYTHING ELSE WAS NORMAL.

Data retrieved from NASA's ASRS site as of January 2009 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.