  The dynamics of two-dimensional three-component (2D3C) flows is relevant to
describe the long-time evolution of strongly rotating flows and/or of
conducting fluids with a strong mean magnetic field. We show that in the
presence of a strong helical forcing, the out-of-plane component ceases to
behave as a passive advected quantity and develops a nontrivial dynamics which
deeply changes its large-scale properties. We show that a small-scale helicity
injection correlates the input on the 2D component with the one on the
out-of-plane component. As a result, the third component develops a non-trivial
energy transfer. The latter is mediated by homochiral triads, confirming the
strong 3D nature of the leading dynamical interactions. In conclusion, we show
that the out-of-plane component in a 2D3C flow enjoys strong non-universal
properties as a function of the degree of mirror symmetry of the small-scale
forcing.
