It's quite common for a Chinook to have a machine gun or even minigun on the sides.
http://www.dillonaero.com/uimages/chinook/chinook_close_up.png
http://www.chinook-helicopter.com/standards/areas/Images/RAF_M134_Minigun.jpg
It would be awesome if the Xenonaut Chinook had them too. Of course they would be fixed and have a limited angle but they could help out if the Chinook lands close to aliens.