  Point-contact Andreev reflection spectroscopy was performed on single
crystals of the heavy-fermion superconductor PrOs$_{4}$Sb$_{12}$, down to 90mK
and up to 3Tesla. The conductance spectra showed multiple structures, including
zero-bias peaks and spectral dips, which are interpreted as signatures of
multiple pairing gaps, one clearly having nodes. Samples with 2% Ru replacing
Os were also measured, showing pronounced spectral humps consistent with the
emergence of a non-nodal gap. Detailed analysis of the spectral evolution
revealed a magnetic field-\emph{vs.}-temperature phase diagram for
PrOs$_{4}$Sb$_{12}$ characterized by two distinct superconducting order
parameters.
