Given the right ratio of helium to whatever you want lifted, yes. Castle Wulfenbach has a few extra apparatus to keep it afloat, however.

[He points to the miniature steamstacks on the back, which are currently belching ickle teeny clouds of hot steam.]

At its full size it is quite beyond the range of being lifted by helium alone, especially not to the heights it must reach. Thus, a steam engine to help it along, as well as coincidentally providing most of the internal power.