On March 29, 2024, about 1141 eastern daylight time, an experimental amateur-built Vans RV9A airplane, N387E, was substantially damaged when it was involved in an accident near Pickens County Airport (JZP), Jasper, Georgia. The private pilot sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 test flight. A part-owner/builder of the airplane stated that the the accident flight was the second flight during the phase one flight testing and the airplane had accumulated about one hour of total time. The accident pilot, who was also a builder of the airplane stated that the purpose was to remain near the JZP airport and obtain engine performance data. The pilot reported that after a normal takeoff, he maintained 4,000 ft mean sea level near the airport to observe engine performance. The observations were unremarkable, and he then descended to return to the airport traffic pattern. The pilot reported that while approaching a left downwind for runway 34, he observed engine rpm decline and the EFIS timer announced, “change fuel tank.” The pilot subsequently engaged the fuel boost pump and switched from the left to right fuel tank, which was followed by a complete loss of engine power. The pilot elected to land in a field, and during the landing the left wing struck a utility pole. The pilot recalled that the boost pump remained running after the forced landing, and he subsequently shut the pump off. According to the part-owner and builder of the airplane, who was monitoring the test flight operations from the ground, the preflight was normal and the pilot radioed to him after about 15 minutes of flying that everything was proceeding normally. After hearing an emergency locator transmitter (ELT) sound over the radio, he was able to locate the accident site within a few minutes. He observed that the fuel selector was selected to the right tank and during recovery operations, about 2.5 gallons of fuel was drained from the right wing, with additional fuel in the grass surrounding the accident site. According to a Federal Aviation Administration (FAA) inspector who examined the airplane at the accident site, the airplane impacted the utility pole and the left wing was partially separated from the fuselage. The left wing and fuselage sustained substantial damage. Examination of the airplane and engine found that the fuel strainer contained about 4 ounces of clean fuel. The mechanical fuel pump was tested and found operational. The fuel vent in the right wing tank was clear and vented normally. The inspector removed the fuel selector and discovered that the right fuel tank line "B" nut (located at the fuel selector) exhibited low torque. There was no evidence of fuel staining or leaking around the fuel selector. The fuel line from the fuel selector to the engine was dislodged from impact damage. An engine test run was attempted. Due to impact damage, the starter would only partially engage; however, the engine exhibited continuity and the Nos. 1 and 4 cylinders fired during the test. Review of the carburetor icing probability chart found that the engine was not at risk for icing during the flight. The airplane was equipped with an Advanced Flight Systems AF-5600 multifunction display. Data was downloaded from the device; however, the files contained no flight data.