We have been making cargo bags for CFA Aviation units for nearly a decade now.  Our Helibag is a 204 litre, super tough cargo bag.  Rated lift points that are sewn together to form a sling.  It has 6 handles, external and internal compression straps, internal pockets, YKK #10 zip and A5 size id window.  Construction is a double layer base panels, plywood and foam base plate. Its made of Kordux Ripstop heavy duty canvas, at 530grams/square meter it doesn't get tougher than this.