What happened
On July 13, 2024, at approximately 10:45 mountain daylight time, a McDonnell Douglas Helicopter 369E, registration N473E, was conducting a Part 91 air tour flight near Sedona, Arizona. During the flight, the pilot maneuvered the aircraft to allow a passenger to take photographs. While performing a steady descent, the helicopter began an uncommanded yaw to the right.
The pilot attempted to counteract the spin with left pedal input, but the rightward yaw continued. During this period, the low rotor RPM warning horn activated, and the pilot observed flashing digits on the Turbine Outlet Temperature (TOT) gauge. In response, the pilot increased the collective. To manage the situation, the pilot lowered the collective and nosed the aircraft down to initiate an autorotation. While the airspeed increased and the yaw ceased, the helicopter experienced a hard landing that caused the left skid to shear off. Despite the impact, the pilot maintained directional control and kept the aircraft upright.
After the initial landing, the pilot checked the engine instruments and increased the collective to attempt a takeoff. After determining the aircraft felt normal, the pilot returned to Cottonwood Airport (P5 and P52) in Cottonwood, Arizona. Upon arrival at P52, the pilot landed on the right skid and disembarked the three passengers. The pilot then moved the helicopter to a grass area and landed on the right skid again. After pulling the fuel cutoff switch and lowering the collective, the helicopter rolled to the left and came to rest on its left side. There were no injuries to the pilot or the three passengers.
The investigation
The helicopter sustained substantial damage to the drive train and was recovered to a secure facility for examination.