  In dimensions larger than 3 a modified field strength for Rarita-Schwinger
type fields is constructed whose components are not constrained by the field
equations. In supergravity theories the result provides a modified
(supercovariant) gravitino field strength related by supersymmetry to the
(supercovariantized) Weyl tensor. In various cases, such as for free
Rarita-Schwinger type gauge fields and for gravitino fields in several
supergravity theories, the modified field strength coincides on-shell with the
usual field strength. A corresponding result for first order derivatives of
Dirac type spinor fields is also presented.
