  On-shell helicity methods provide powerful tools for determining scattering
amplitudes, which have a one-to-one correspondence with leading power helicity
operators in the Soft-Collinear Effective Theory (SCET) away from singular
regions of phase space. We show that helicity based operators are also useful
for enumerating power suppressed SCET operators, which encode subleading
amplitude information about singular limits. In particular, we present a
complete set of scalar helicity building blocks that are valid for constructing
operators at any order in the SCET power expansion. We also describe an
interesting angular momentum selection rule that restricts how these building
blocks can be assembled.
