On April 1, 2024, about 1200 eastern daylight time, a Beech 95B55 airplane, N7371R, was substantially damaged when it was involved in an accident near St. Augustine, Florida. The pilot and pilot-rated passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 test flight. According to the pilot, he and the pilot-rated passenger, who was also a mechanic, departed Northeast Florida Regional Airport (SGJ), St. Augustine, Florida, on a post-maintenance test flight after the airplane had undergone an extensive annual inspection. About 500 ft above ground level the pilot initiated a turn toward the west to go to an area where he could proceed with the engine break-in process. At that time, the airplane lost complete electrical power. The pilot decided to return to SGJ and land. Because the airplane had lost radio communication, the passenger contacted the control tower using his mobile phone and declared an emergency. The pilot and the pilot-rated passenger then attempted to manually lower the landing gear using the emergency landing gear extension handle. Both said they turned the handle until it would not turn any further; however, the pilot said that he may not have been able to turn the handle enough to fully extend the landing gear to the down-and-locked position. The pilot-rated passenger asked the control tower if the landing gear looked extended, and the tower responded that they could see three landing gear down but could not tell if they were fully extended. When the airplane touched down, the right main landing gear collapsed. The airplane slid off the right side of the runway and collided with a runway sign, resulting in substantial damage to the fuselage and right wing. Examination of the wreckage by an FAA inspector could not determine the reason for the electrical failure. Attempts to conduct a functional test of the landing gear were unsuccessful due to impact damage.