On March 11, 2021, about 1512 eastern daylight time, a Cessna 421B, N80056, was substantially damaged when it was involved in an accident at Macon County Airport (1A5), Franklin, North Carolina. The pilot and two passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, after a normal start, taxi, and run-up, he initiated the takeoff roll from the 5,000-ft-long, asphalt runway. He called out airspeeds in 10-knot increments toward a planned rotation airspeed of 100 knots; however, at 90 knots, the airplane’s acceleration “lagged,” and the airplane reached a maximum airspeed of 92 knots. He noticed that the runway length was decreasing and elected to abort the takeoff with about 1,500 ft of remaining runway. He pulled both throttles to idle and applied maximum braking. The pilot stated that he did not sense the airplane slowing down but observed tire marks on the runway postaccident that were consistent with braking. The airplane departed the end of the runway, continued down a slope, and through a fence before coming to rest. A postcrash fire ensued. All the occupants exited the airplane safely. Examination of the runway by a Federal Aviation Administrator inspector revealed tire skid marks that began 1,200 ft from the runway end and continued into the grass leading to the airplane. An examination of the airplane by an NTSB investigator revealed the entire cockpit and cabin areas were destroyed by fire. All flight instrument readings and control positions were unreliable due to fire damage. The parking brake control was found in the off position. All hydraulic brake lines were destroyed by fire, and the main landing gear sustained fire and impact damage. Examination of the left and right engines revealed that both were heavily fire damaged but that the engine cases remained intact and were not breached. Power and valvetrain continuity could not be established due to impact and fire damage. The accessories on both engines were also fire damaged. Both propeller assemblies remained attached to the propeller hubs on both engines but exhibited fire and impact-related damage.