  In helical turbulence a linear cascade of helicity accompanying the energy
cascade has been suggested. Since energy and helicity have different
dimensionality we suggest the existence of a characteristic inner scale,
$\xi=k_H^{-1}$, for helicity dissipation in a regime of hydrodynamic fully
developed turbulence and estimate it on dimensional grounds. This scale is
always larger than the Kolmogorov scale, $\eta=k_E^{-1}$, and their ratio $\eta
/ \xi $ vanishes in the high Reynolds number limit, so the flow will always be
helicity free in the small scales.
