  The consequences of a recently introduced irreducible pionic effect in low
energy nucleon-deuteron scattering are analyzed. Differential cross-sections,
nucleon (vector) and deuteron (vector and tensor) analyzing powers, and four
different polarization transfer coefficients have been considered. This
3NF-like effect is generated by the pion-exchange diagram in presence of a
two-nucleon correlation and is partially cancelled by meson-retardation
contributions. Indications are provided that such type of effects are capable
to selectively increase the vector (nucleon and deuteron) analyzing powers,
while in the considered energy range they are almost negligible on the
differential cross sections. These indications, observed with different
realistic nucleon-nucleon interactions, provide additional evidences that such
3NF-like effects have indeed the potential to solve the puzzle of the vector
analyzing powers. Smaller but non negligible effects are observed for the other
spin observables. In some cases, we find that the modifications introduced by
such pionic effects on these spin observables (other than the vector analyzing
powers) are significant and interesting and could be observed by experiments.
