On August 28, 2001, about 1600 Pacific daylight time, a de Havilland DHC-8-102, N827PH, operated by Horizon Airlines as flight 2185, experienced roll control difficulties shortly after takeoff from Klamath Falls International Airport, Klamath Falls, Oregon. The two pilots, one flight attendant, and 37 passengers were not injured. The airplane was being operated as a scheduled, domestic, passenger flight under the provisions of Title 14 CFR part 121, when the incident occurred. Visual meteorological conditions prevailed and an instrument flight plan was in effect at the time of the incident. The airplane continued to its planned destination, Portland International Airport, Portland, Oregon, and landed without further incident. The operator reported the airplane departed runway 32 at Klamath Falls. Shortly after departure, during the initial climb, the first officer noted stiffness in the flight controls when attempting to roll the airplane to the left. After assessing the situation, the captain elected to continue the climb. Shortly after level off, the crew noted that the stiffness increased proportionally with airspeed. This was also noted during the descent phase of the flight, specifically, the first officer stated the resistance increased for left roll inputs as the aircraft accelerated. The captain reported that they attempted to relieve the pressure with aileron trim, however, when the trim indicator reached the first index on the indicator, the control wheel "snapped" approximately 25 degrees and the airplane banked to the right. The crew reported that as the airplane slowed, while on approach, the roll control stiffness decreased. After landing, the crew accomplished a full control check and noted no abnormal indications with the ailerons or spoilers. The airplane sustained no damage during the incident. Post-incident inspection of the airplane by personnel from Horizon Airlines and the Federal Aviation Administration, Portland Flight Standards District Office, disclosed a number of discrepancies that are believed to have contributed to the stiff flight controls. The items are as follows: the right control yoke chain tension was high; the right aileron spring tab hinge bearing did not rotate freely; the left aileron spring tab aft spring tension was low and the contact stud was worn; the right aileron spring tab tension was low and the contact stud was worn; the left aileron hinge bearing did not rotate freely. Additional inspection information attached.