On February 15, 2020, about 1438 eastern standard time, a Rockwell International 112B, N377SB, was substantially damaged when it was involved in an accident near Knoxville, Tennessee. The pilot sustained a minor injury and the passenger was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that after departure from Bowman Field Airport (LOU) he proceeded to Knoxville Downtown Island Airport (DKX) and with calm winds, entered an extended left base leg of the airport traffic pattern for runway 08. He turned onto the final approach leg of the airport traffic pattern, and reported touching down 1/3 down the runway. A few seconds after landing, he equally applied the brakes, and about 1 or 2 seconds after the airplane began to slow, he felt, "a very aggressive turn to the left," which he described as if the airplane had suddenly encountered a 20+ knot crosswind. He applied right rudder input but that did not correct the left turn. The airplane departed the runway onto grass, where he attempted to slow the airplane. The airplane then veered again to the left and this time he had no rudder authority. He instructed the passenger to brace for impact and reported coming to an abrupt stop. When the pilot exited the airplane, he noted that the left main landing gear tire was deflated. According to the Federal Aviation Administration inspector who examined the accident site and airplane, rubber transfer on the runway consistent with the left tire began about 1,900 ft from the approach end of the runway. After exiting the runway, the airplane traveled about 600 ft, and impacted a drainage ditch, causing the nose landing gear to collapse. The left main landing gear tire exhibited a flat spot through the tread. Postaccident examination of the airplane's brake system revealed no evidence of preimpact failure or malfunction.