The shear flow induced deformation of the planar cholesteric structure is modelled numerically, taking into account long pitch flow-aligning material. Three pitch-to-thickness ratios in five configurations are considered. Unwinding of the cholesteric helix due to the flow alignment is found. This process has a threshold character, when the mid-plane director is perpendicular to the plane of shear; otherwise it is continuous. The transverse component of the flow is always present. At high stress, the director in the prevailing part of the layer is oriented at the flow-aligning angle.