Accident Overview
On August 17, 2018, at about 1050 Pacific daylight time, a Hughes 369D helicopter, registration N105JL, sustained substantial damage during an accident near Riverside, California. The flight instructor received a minor injury, while the pilot receiving instruction was seriously injured. The helicopter was being operated under Title 14 Code of Federal Regulations Part 91 as an instructional flight.
Sequence of Events
The flight involved instruction in autorotations. The pilot performed several power recovery autorotations, after which the instructor demonstrated a full-touchdown 180° autorotation. The pilot then executed several power recovery 180° autorotations. Subsequently, the instructor asked the pilot to perform a full-touchdown 180° autorotation. As the pilot turned the helicopter toward the runway, the instructor observed that the helicopter would be short of the intended landing zone and advanced the throttle to initiate a power recovery. The instructor realized the descent rate was greater than anticipated and instructed the pilot to level the helicopter's skids. The instructor reported feeling the absorbers on the skids collapsing upon touchdown, followed by a large bump and rapid rotation of the airframe. After shutting off the fuel, the instructor egressed and noticed that the pilot receiving instruction had been ejected from the helicopter during the accident.
Post-Accident Examination
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, and no instructions from the manufacturer indicated that cotter pins were required to be installed.
Manufacturer Service Bulletin
Following the accident, on November 20, 2019, MD Helicopters issued Mandatory Service Bulletin SB369D-227, titled "INSTALL COTTER PINS IN THE SEAT-BELT INSTALLATION." The bulletin stated that the action was "…to prevent the hook-ends from disengagement from the attachment points" and 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."