There is a present need for simulating and measuring the inlet swirl distortion generated by airframe/engine system interactions in a full-scale, turbofan ground testing environment. Understanding transonic fan response to swirl distortion requires thorough documentation of the swirl development as it approaches the fan. In past efforts, a method has been developed for generating arbitrary swirl distortions for ground test. The stream-wise development of swirl distortions generated in situ with this technique have been measured using stereoscopic particle image velocimetry (PIV) in a research turbofan engine. Data were obtained at 50% and 65% corrected fan speed for a StreamVane swirl-generating device designed to mimic specific hybrid wing/body configuration flight conditions. Measurements were taken at an aerodynamic interface plane (AIP) of one diameter upstream of the fan face and at a measurement plane 3.5 inches (0.17D) upstream from the fan face. A number of practical considerations and post-processing steps are discussed which enable the application in the full scale engine. The results provide the first experimental view of three-velocity component flow due to transonic fan/swirl distortion interaction, demonstrating new tools for improving airframe/engine integration.