An accessory assembly of a turbine engine has a support structure and a shaft coupled to the support structure by means of a pair of main bearings and provided with an end portion, which has a shear neck designed to break when the torque transmitted to that shaft exceeds a predetermined design threshold; the accessory assembly also has a gear, which defines a motion inlet, is fixed to the end portion and, when said shear neck breaks, remains supported by a single secondary bearing; the latter is distinct from said main bearings and is arranged axially between said shear neck and the gear.