A 5-helix S^ (3) (1, 5) of centre c is a 3-uniform hypergraph, with 5 hyperedges, all having in common exactly the centre c of degree 5, and the remaining vertices of degree 1. In this paper we determine the spectrum of S^ (3) (1, 5) -designs of index 2 with pairwise distinct blocks.
Causa et al. (Wed,) studied this question.