Universal Heat Transport in [Formula presented]

We present the temperature dependence of the thermal conductivity [Formula presented] of the unconventional superconductor [Formula presented] down to low temperatures [Formula presented]. In the [Formula presented] limit we found a finite residual term in [Formula presented], providing clear evidence for the superconducting state with an unconventional pairing. The residual term remains unchanged for samples with different [Formula presented], demonstrating the universal character of heat transport in this spin-triplet superconductor. The low-temperature behavior of [Formula presented] suggests the strong impurity scattering with a phase shift close to [Formula presented]. A criterion for the observation of universality is experimentally deduced.