Now there was an incident with a 737 in Europe, where during the cruise the crew forgot that they were fuel balancing – cross feed open.
At the next leg-change the autopilot (LNAV) had difficulty in completing the turn due to the significant control force offset previously used to hold the wings level.
The crew disconnected the autopilot, anticipating a balanced lateral control force, it was not.
The aircraft rolled beyond 87 deg before a recovery was made.
Also, as another scenario, consider ‘what if’ - a slat fails to retract during departure; the autopilot has difficulty in responding. The crew take over and fly manually, but are confused by the asymmetric control forces / offset stick position; their actions are transferred by illusion/error into the pitch control. The aircraft rolls and pulls into a tight turn at low level. (Flash?)
Try the scenarios above in the simulator; learn about ‘force’ illusions, the differences in stick / wheel position vs zero force position and how we often assume a constant relationship between them. Incorrect trim either due to trim input or external trim force can be a killer particularly in roll.
But of course pitch trim can lead to similar problems. An A310 crew overpowered the autopilot during a go around. The auto trim opposed the stick force and applied full nose up trim, the aircraft ‘stalled’ twice with 90 deg wing drop before recovering. (N.B. all aircraft should now be modified to prevent this happening again)
A310