On December 8, 2019, about 1405 Atlantic standard time, an experimental amateur-built Parsons Two Place #1 gyroplane, N446PS, was substantially damaged when it impacted terrain near Naguabo, Puerto Rico. The private pilot sustained serious injuries. The gyroplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, about 10 minutes after departure while in cruise flight at 55-60 mph, he began to feel a vibration in the airframe and an "abnormal drag." He reduced the engine power, and about that time, he felt the propeller sever the rudder cables. As he looked back, he saw the rudder separate from the airframe and the gyroplane began to spin. The pilot shut down the engine to reduce the torque and attempted to maintain control as the gyroplane rapidly descended until it impacted the ground. Examination of the wreckage by a Federal Aviation Administration inspector revealed that the gyroplane came to rest on the right side. The main rotor blades were impact damaged and cut branches were located nearby. The propeller blades remained attached to the engine and the engine remained attached to the airframe. The rudder was not located after the accident. Photographs of the fractured bolt section that attached the rudder to the fuselage were sent to the National Transportation Safety Board Materials Laboratory for examination, which revealed that the bolt fractured as a result of reverse bending fatigue. According to the preflight checklist for the gyroplane, the pilot should check the rudder for "condition and security, check surface for delamination, check rudder cables (rudder end) for fraying and nico clamps for security." After the accident, the manufacturer of the gyroplane kit updated the preflight checklist to include checking the rudder for "condition and bolt security, check surface for delamination, check rudder cables (rudder end) for fraying and nico clamps for security."