On August 17, 2018, about 1050 Pacific daylight time, a Hughes 369D helicopter, N105JL, was substantially damaged when it was involved in an accident near Riverside, California. The flight instructor sustained a minor injury, while the pilot receiving instruction was seriously injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The pilot performed several power recovery autorotations, then the instructor demonstrated a full-touchdown 180° autorotation. The pilot subsequently performed several power recovery 180° autorotations before the instructor asked him to perform a full-touchdown 180° autorotation. The instructor stated that, as the pilot turned the helicopter toward the runway, he saw that they were going to be short of the intended landing zone and advanced the throttle to perform a power recovery. The instructor then realized that the descent rate was greater than he anticipated, and he instructed the pilot to level the helicopter’s skids. The instructor reported that he “felt the absorbers on the skids collapsing” as the helicopter touched down, then he felt a large bump then rapid rotation of the airframe. After shutting off the fuel, the instructor egressed and saw that the pilot receiving instruction had been ejected from the helicopter during the accident sequence. Examination of the seat belts revealed that no cotter pins were installed in the hooked end fittings of each seat belt. The manufacturer reported that cotter pins were not delivered with the seat belts, nor were there any instructions from the manufacturer that cotter pins were required to be installed. Following the accident, on November 20, 2019, MD Helicopters issued Mandatory Service Bulletin SB369D-227, entitled “INSTALL COTTER PINS IN THE SEAT-BELT INSTALLATION.” In part, the Service Bulletin was issued “…to prevent the hook-ends from disengagement from the attachment points.” The bulletin further noted that, “Failure to comply with this bulletin can cause a pilot, copilot, or passenger to fall out of the helicopter in flight or on the ground.”