In the superfluid phases of liquid 3He with p-wave spin triplet pairing, all of the continuous symmetry except for the translational symmetry are broken, exhibiting extraordinarily rich physical phenomena. In particular, the surface scattering in unconventional superfluids/superconductors induces quasi-particle sub-gap bound states spatially localized near the surface within the coherence length xo, called the Andreev surface bound states (ASBS).  We investigated 3He-B properties using a micro-machined mechanical oscillator developed in our laboratory.  Our results revealed fascinating features in the damping of the oscillator and in its nonlinear behavior in the zero temperature limit.  We will discuss a unique process involving multiple Andreev scattering in the surface states that might be the underlying physics for the observed behavior.