  Quasiparticle relaxation rate,$\tau_{p}^{-1}$, and the shear viscosity tensor
of the A_1-phase of superfluid 3He are calculated at low temperatures and
melting pressure, by using Boltzmann equation approach in momentum space. The
collision integral is written in terms of inscattering and outscattering
collision integrals. The interaction between normal and Bogoliubov
quasiparticles is considered in calculating transition probabilities in the
binary, decay and coalescence processes. We obtain that both
$\tau_{p\uparrow}^{-1}$ and $\tau_{p\downarrow}^{-1}$ are proportional to $T^2$
>. The shear viscosities $\eta_{xy}$, $\eta_{xz}$ and $\eta_{zz}$ are
proportional to $(T/T_c)^{-2}$. The constant of proportionality of the shear
viscosity tensor is in nearly good agreement with the experimental results of
Roobol et al., and our exact theoretical calculation.
