On August 29, 1995, at 1547 eastern daylight time, a Cessna 310K, N6921L, operated by the private pilot/registered owner, was destroyed when it veered off the left side of the runway during the landing roll, and collided with trees at Columbiana County Airport, Columbiana, Ohio. The pilot, the sole occupant, reported minor injuries. Visual meteorological conditions prevailed for the personal flight, which operated under 14 CFR Part 91. The flight originated from Youngstown, Ohio, approximately 1520. The pilot stated that the airplane was at Youngstown for maintenance repairs for a torque link failure. When he was informed that the repairs were completed, the pilot flew the airplane back to it's home base airport in Columbiana, Ohio. He stated that the flight was smooth and uneventful, but that during the landing roll he "...felt something drag on the left side...causing the aircraft to veer violently to the left." The aircraft departed the left side of runway 25 and struck trees located approximately 150 feet to the left of the landing surface. Postaccident examination of the aircraft revealed that the washer under the torque link attachment bolt head was not installed, and the torque links had separated.