Uncommanded Movement Of The Trimmable Horizontal Stabilizer Control Wheel For Reasons That Could Not Be Determined...
Analysis: The flight crew reported that, when the airplane climbed through flight level 360, the trimmable horizontal stabilizer (THS) trim wheel began to move “very quickly” forward and aft, creating small pitching oscillations. No message appeared on the airplane’s electronic centralized aircraft monitor, and no flight deck alerts annunciated. The crew decided to turn off the autopilot to isolate the malfunction. However, when the autopilot was off, the trim wheel continued to move erratically. The crew then reengaged the autopilot, and small pitch oscillations resumed.