It depends a bit on what you want to achieve.
Currently you have created a scene in blender containing multiple parts that together result in your BlackHawk helicopter. If you just need a single object in Ogre, you can combine the elements inside Blender into one object, export that and use the same loading code as before (using the new .mesh file name of course).
If you want the individual parts to stay independent, you will have to load them into Ogre one by one or use one of the many DotScene loaders (e.g. this one or that one or the one that also handles user data) and point it to your "BlackHawk.scene" file (which should reference all helicopter parts).