Operational gas turbine engine housing or casing dynamic strain, temporary or permanent displacement and/or temperature is measured by a distributed fiber optic sensing system (DFOSS) utilizing optical frequency domain reflectometry (OFDR) that is coupled to the turbine engine housing. The DFOSS/OFDR system measures localized variances in strain along the length of an optical fiber (OF), which are correlated with turbine engine housing displacement. Temperature influence on the measured localized strain variances is accounted for by obtaining temperature information from an another measurement system or by taking the same type OFDR measurements on unrestrained optical fiber (OF) and deriving compensated strain measurements that are not temperature influenced. The derived strain measurements along the DFOSS are correlated with housing displacement. Other embodiments include separate displacement measuring modules, each including DFOSS optical fibers, coupled along the engine housing.