I can only speak for US Blackhawks but the pack between the gunner's seats is quite possibly a survival kit. It is also common for flyaway gear to be stowed in a kit bag between the seats as well. It is quite a useful space and all kinds of things get stowed there in addition to these.
Nice work so far! I really like this kit, I can only pick nits with it. There are a few things that can be easily tweaked but not really noticeable unless you know to look. I'll have to not be such a stranger an follow this along. Let me know if you need any references, I don't really have anything on the Aussie birds but info on the S-70 airframe is no problem.