Bell 407 crash near Johannesburg-Grand Central Airport, Gauteng, South Africa

A chief flight instructor and a pilot on a proficiency check flew autorotation exercises over the main taxiway at Grand Central Airport. Two were uneventful. On the third the engine did not spool up in time and rotor rpm was low, so the instructor took control, and the skids struck the taxiway hard. The crew flew back to Ultimate Heliport without further difficulty and found on inspection that the tops of both vertical stabilisers and one main rotor blade were damaged. The Civil Aviation Authority concluded that a slow engine spool up during the autorotation recovery caused the hard landing, during which a main rotor blade struck the stabilisers.