On April 16, 2020, about 1145 Eastern standard time, a Beech A36, N66FN, sustained substantial damage when it was involved in an accident near Cincinnati, Ohio. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. The pilot reported that he was flying the airplane from Indianapolis, Indiana (UMP), to Cincinnati, Ohio (LUK), where maintenance was to be performed. During the flight, the pilot was performing an altitude leaning schedule to attempt to diagnose high exhaust gas temperature (EGT) readings. Enroute, the pilot performed step-up climbs to 14,000 ft to record power settings. After completing the schedule of tests, the pilot was descending to about 2,500 ft and noticed an "unusual" vibration that he had not experienced before. After checking the engine analyzer, he noticed that one of the engine cylinders was not producing an EGT reading. A few moments later, another cylinder EGT dropped offline, then a third cylinder. Cylinder EGTs continued to drop offline then the engine "quit." The pilot was not able to restart the engine and declared an emergency. The airplane was over a heavily populated area just north of downtown Cincinnati, so the pilot maneuvered the airplane for an emergency landing on a roadway. Upon landing, the left wing struck a wooden post along the edge of the roadway. The nose pitched to the left and the airplane landed hard on the right main landing gear and the nose landing gear, resulting in a landing gear collapse. The airplane then pitched right and struck another wooden post on the opposite side of the roadway with the right wing. The nose of the airplane contacted a concrete bridge abutment and the airplane slid under an overpass. The pilot secured the fuel and master switch and exited the airplane. A postaccident examination of the airplane and engine was conducted. The top spark plugs were removed, and compression was verified to the cylinders. The air intake hoses and clamps were verified secure and tight, and no obstructions were noted. The magnetos were verified to spark at all terminals. The engine controls were checked to be free and had full travel. The mixture control screen was removed and found to be free of debris. The fittings and hoses were checked for security on the mixture control, fuel manifold valve, and fuel pump. Both the fuel inlet and fuel return line fittings on the fuel pump were found to be loose and could be turned by hand. No adjacent impact damage was noted around the loose fittings. According to maintenance records, the fuel pump had been removed and replaced on April 14, 2020, 2 days prior to the accident. According to the engine manufacturer, a loose inlet fitting could result in a loss of engine power.