On September 1, 2024, about 1520 central daylight time, a Diamond DA42 airplane, N705JP, sustained substantial damage when it was involved in an accident near Mandan, North Dakota. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, he departed Bismark Municipal Airport (BIS) and requested vectors for the RNAV 31 approach at Mandan Regional Airport (Y19) from air traffic control. The pilot reported that his approach to Y19 was uneventful and estimated that he touched down about 100 ft past the numbers for runway 31. The pilot attempted to decelerate, keeping constant pressure on the brakes. The pilot stated that the brakes were not working until he approached the end of the runway, at which point the brakes “slowly got responsive.” The pilot stated that the pilot-rated passenger asked about conducting a go-around during the landing attempt, but the pilot was focused on stopping. The pilot reported that a go-around could have been possible and that it was a “shock” that he couldn’t stop the airplane. According to the pilot, he used a flap setting of 20°, or APP during the approach and landing. According to the pilot-rated passenger, the landing at Y19 was so smooth that he did not notice the airplane had touched down until the nose wheel shimmied. The passenger stated that the airplane appeared to touchdown within the first third of the 4399-ft runway and the landing roll seemed normal, but he did not feel as much deceleration as he expected. The airplane exited the paved surface of the runway and impacted a runway end identifier light, resulting in substantial damage to the fuselage. According to the airport manager, who examined the runway surface after the accident, there were visible tire skid marks leading off the end of the runway. A postaccident examination of the brake system revealed that the brakes appeared to function normally. There was no evidence of leaks at the hoses, calipers, or at the master cylinders attached to the rudder pedals. Brake application was firm and, with the brakes applied, would have prevented the movement of the airplane. The brake pads appeared to have adequate material left to not impede braking action. The right brake pads were worn more than the left, but not beyond the limit of function. An aircraft performance study using ADS-B and engine ECU data concluded that the airplane touched down at 92 kts calibrated airspeed, 6 kts faster than the 86-kt VREF speed calculated from the Airplane Flight Manual. The airplane’s weight on wheels (WOW) sensors indicated that the airplane was not fully on the ground until 2,136 ft past the runway threshold. The airplane was landed in a 6.3-kt tailwind that would have increased landing distance by 21%. Considering all factors, the study concluded that there was insufficient runway remaining after the touchdown for the airplane to stop. Additionally, the study concluded that had the pilot used the LDG flap setting there would have been sufficient runway remaining. According to the AFM, ground roll distances for flaps LDG are about 73% of the ground roll distances for flaps APP/UP. If that ratio holds for the ground roll estimate above of 2,411 ft with flaps APP, the ground roll estimate for flaps LDG would be 1,760 ft. A ground roll of 1,760 ft would have allowed the airplane to stop on the runway.