True ternary fission and Tin-accompanied ternary fission of 242Pu are studied by using the 'Three Cluster Model'. True ternary fission is considered as a formation of heavy fragments in the region with comparable masses. The possible fission channels are predicted by the potential-energy calculations. Interaction potentials, Q-values and relative yields for all possible fragmentations in equatorial and collinear configurations are calculated and compared. It is found that ternary fission with formation of a double magic nucleus like is more probable than the other fragmentations. Also, the kinetic energies of the fragments for the group , and are calculated for all combinations in the collinear geometry as a sequential decay.