The objective of this proposal is to solve the field-induced magnetic structure of a newly synthesized brownmillerite. Under normal conditions there are three different magnetic regions as a function of temperature, but we have found that the field/cooling path taken in field and temperature results in a very different magnetic state at lowest accessible temperatures. We have reason to believe that this metastable magnetic state originates from magnetic frustration that we have observed at higher temperature. In order to prove this, we will be accessing this non-equilibrium magnetic state by flash cooling a single crystal of the material down to 4 K within a large applied magnetic field, and then measuring the neutron diffraction pattern.