Aesir,
Those guys who said weight of ice is an issue are talking through their hats. The typical helo cannot accrete enough ice in weight gained to make up for the fuel burn in weight lost, this is also true for most airplanes.
Pilots often confuse the large torque increase they see with the "load of ice" they accumulate, but that is a misnomer. The huge performance loss due to the drag on the blades and the wings of an airplane are the way the ice gets you. It is not uncommon for a helo to experience a 10% torque rise within a minute or two when ice forms on the blades. In several hours of continuous icing flight I have never seen more than a few pounds (20, 30?) of ice form on the blunt forward ends of fuselage areas, worst case.