WPR18LA226

The pilot receiving instruction was performing a full-touchdown, 180° autorotation when the instructor noted that the helicopter was going to be short of the intended landing zone and advanced the throttle to initiate a power recovery. The helicopter continued to descend and landed hard and rolled over, resulting in substantial damage. The instructor reported no mechanical malfunctions with the helicopter or engine that would have precluded normal operation. It is likely that the instructor’s delayed response to the helicopter’s excessive rate of descent resulted in the hard landing. After egressing the helicopter, the instructor noted that the pilot receiving instruction had been ejected from the helicopter during the accident sequence. Examination of the restraint systems revealed that the cotter pins for the hook-end fitting that attached to the airframe seat belt fittings had not been installed. The centrifugal force generated by the rotation of the helicopter during the accident sequence was likely sufficient for the hook-end fitting, void of the cotter pin, to separate from the seat belt fitting, which then resulted in the student being ejected from the helicopter. As a result of the accident, the manufacturer issued a mandatory service bulletin requiring the installation of cotter pins in the seat belt assemblies.

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.”