Dash 8-100
Aircraft Equipment Problem Critical
General Maintenance Action
Aircraft
I was acting as pilot monitoring on routine revenue flight.  Flight proceeded uneventfully in perfect VFR weather to  destination.  Approach proceeded normally under manual flying without autopilot engaged until the landing flare.  As the plane flared for landing the Captain seemed to struggle with control yoke and made a verbal exclamation.  Immediately afterwards the aircraft landed normally.  During rollout as the Captain transferred to the nose wheel steering tiller; he asked me to take the control yoke and try to deflect it to the left.  At about 15-20 degrees of control deflection to the left; the yoke felt jammed.  I tried successive and repeated movements back to the right and then back to the left.  Each time the yoke felt jammed in the same spot but each time the jam felt softer.  Eventually I used more  force; approximately 15-20 lbs; and yoke seemed to break free.  Subsequent movements of the yoke eventually caused the jam to disappear altogether.  The flight arrived at the gate at which time Maintenance Control was advised.  The aircraft was then inspected and approved for ferry.  The ferry flight proceeded normally and arrived without incident.
DHC8-100 First Officer is informed by the Captain during landing of jammed ailerons in the left wing down direction.  The First Officer is asked to try it for himself and initially feels resistance when rolling to the left but repeated attempts result in the resistance disappearing.