On August 1, 2020, about 0130 central daylight time, a Piper PA28R airplane, N9765C, was substantially damaged when it was involved in an accident at Seiling Airport (1S4), Seiling, Oklahoma. The pilot and three passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he arrived with the same three passengers earlier that day for a rodeo event. After the rodeo, they returned to the airplane about 0100 and prepared to depart. The pilot confirmed that the takeoff weight was 2,622.8 lbs (maximum takeoff weight is 2,750 lbs) and that the airplane had 25 to 26 gallons of fuel onboard. He calculated that the airplane required 1,700 to 1,800 ft for takeoff from the 2,435-ft-long runway. He elected not to perform a short field departure and kept the flaps retracted. He added that he “still made the decision to spare every inch of runway” when he taxied the airplane into position at the end of the runway. He held the brakes and advanced the throttle, mixture, and propeller controls full forward. “When the engine was up to speed,” he let off the brakes and began the takeoff roll. He reported that during the takeoff roll, when the airspeed was about 60 knots, he noticed a sound and vibration from the engine, so he aborted the takeoff. He was unable to stop the airplane and it continued off the end of the runway, over a road, and into trees. The responding Federal Aviation Administration inspector reported that the airplane sustained substantial damage to the left wing. A postaccident examination of the engine and airplane did not reveal any mechanical malfunctions or anomalies that would have precluded normal operation. The inspector completed takeoff performance calculations based on the accident conditions and determined that the airplane would have required about 2,000 to 2,100 ft for takeoff. He added that the pilot’s preflight performance calculations underestimated the amount of runway needed to complete the takeoff. NTSB performance calculations determined that the takeoff roll would have been about 2,100 ft based on the accident conditions. The airplane was equipped with an Electronics International Inc. MVP-50P engine monitor, which recorded engine and GPS data. A review of the recorded engine data revealed that the takeoff roll began about 117 ft from the takeoff end of the runway. The distance from the beginning of the takeoff roll until there was a noted reduction in engine rpm and fuel flow was 1,760 ft. The distance from the reduction in rpm and fuel flow until the first reduction in GPS speed was another 242 ft. From this point, the pilot only had 304 ft to stop the airplane before the end of the runway. The pilot reported that he observed 60 knots on the airspeed indicator about the same time he felt the vibration then aborted the takeoff. The data showed that once the airplane achieved 60 knots, it continued down the runway another 5 seconds and 668 ft until the aborted takeoff was initiated. The recorded engine and GPS data did not reveal any anomalies.