The work deals with the investigations of the smecticA-hexaticB phase transition in n-hexyl-4-n-pentyloxybiphenyl-4-carboxylate liquid crystal compound in a single domain homeotropic sample and in a nonaligned sample. The specific heat, the thermal diffusivity, and the enthalpy exchange were monitored over the transition and, at the same time, polarization microscopy observations could be carried out. The transition during the first cooling run was found to be accompanied by a considerably larger defect annealing in the non aligned sample than in the homeotropic one.