Helmet system with a wearable chassis

A helmet system comprising:

• a protective structure having a shape protecting a head of a user from an external impact, which protective structure provides ballistic protection;
• and
• a wearable chassis attached inside said protective structure, wherein the chassis has a body having a shape suitable to be worn on a head of the user such that an inner side of the body is directly facing the head of the user, and the protective structure at least partially covers the body, the chassis comprising
• one or more connection ports for connecting an electronic device, the one or more connection ports located on the chassis,
• a control interface for connecting a control unit,
• a wiring arrangement for connecting the one or more connection ports to the control interface, and
• a mounting arrangement for attaching an accessory device to the chassis, the mounting arrangement located on the chassis, wherein,
• the body has a shape of an upper part of a human head, the body including a top portion and a back portion, a surface of the back portion designed to be facing the back of the head of the user with a shape of the back of the head of the user, and
• the protective structure at least partially covers the top portion and the back portion of the body,
• wherein the mounting arrangement comprises one or more accessory rails for mounting an accessory device,
• wherein the mounting arrangement is provided with one or more of said one or more connection ports for electrically connecting an accessory device attached thereto to the control interface.