Hughes 269C, VH-KZR, Mt Anderson Homestead, 80km South-east of Derby WA, 14 June 1984

After landing, as the pilot lowered the collective lever, the helicopter entered ground resonance. Recovery action was not taken by the pilot and one of the main rotor blades struck a fuel drum. The resulting imbalance of the main rotor system caused the rotor mast to separate from its attachment. An inspection of the helicopter revealed that the undercarriage oleo struts had incorrect and differing inflation levels, and that the main rotor dampers had been incorrectly assembled.