20190523005059A

The student and instructor were attempting to perform a simulated stuck pedal emergency procedure at St. Louis Downtown Airport. After touchdown, while still sliding down the runway, the helicopter began to drift toward the left edge of the runway. To avoid sliding into the soft ground at the runway?s edge the pilots aborted the maneuver by returning the throttle to the governed range and applying up collective to lift the helicopter to a hover. (Note: during this maneuver manual control of the throttle is used for directional control of the helicopter while sliding on the skids. Returning the throttle to the governed range requires the addition of RPM by rolling the throttle to a more open / power increased position). Leaving the runway surface the helicopter began spinning to the left. The instructor applied full right anti-torque pedal but was unable to stop the left-spin before the skids made contact with the ground, resulting in a dynamic rollover type accident. All three main rotor blades were destroyed by powered contact with the ground. Additionally, the tail boom was completely severed just forward of the fenestron and the left horizontal fin was damaged. Further, the skids were misaligned by contact with the ground and there was possible damage to the skid mounting points on the airframe with some airframe damage possible as well. Sudden-stoppage damage is likely to all dynamic components.