The aircraft was equipped with the aircraft manuafacturers wheel/ski undercarriage. At an indicated airspeed of 130 knots the pilot heard a loud bang accompanied by a jolt and then severe vibration, followed by another loud bang and worse vibration. Both left and right skiis had pivoted about their attachments to a position beyond the vertical, creating considerable drag. An emergency landing was carried out, and on touchdown the heels of the skiis contacted the ground which returned them to normal position facilitating a normal roll out.
