Let T_{ijk} be a real 3rd order n x n x n tensor. Do there exist matrices U, V, W \in SO(n) such that the tensor S_{pqr} = sum_{i, j, k} U_{ip}V_{jq}W_{kr}T_{ijk} has the property:
1) S_{1qr} is diagonal;
2)S_{2qr} is upper-triangular?
I'm especially interested in case n=3.