  A measurement of the analyzing powers for the $^2$H$(\vec{p},pp)n$ break-up
reaction was carried out at KVI exploiting a polarized-proton beam at an energy
of 135 MeV. The scattering angles and energies of the final-state protons were
measured using the Big Instrument for Nuclear-polarization Analysis (BINA) with
a nearly $4\pi$ geometrical acceptance. In this work, we analyzed a large
number of kinematical geometries including forward-forward configurations in
which both the final-state particles scatter to small polar angles and
backward-forward configurations in which one of the final-state particles
scatters to large polar angles. The results are compared with Faddeev
calculations based on modern nucleon-nucleon (NN) and three-nucleon (3N)
potentials. Discrepancies between polarization data and theoretical predictions
are observed for configurations corresponding to small relative azimuthal
angles between the two final-state protons. These configurations show a large
sensitivity to 3N force effects.
