This paper presents the results of an investigation to improve design/analysis techniques for aircraft hydraulic systems. A design/analysis tool was developed by integrating control-surface commands and loads obtained from Aircraft Dynamic Simulator Software (ADSS) with an enhanced version of the HYdraulic TRansient ANalysis (HYTRAN) program. Control-surface commands and loads from an ADSS simulation of a selected maneuver were used as dynamic input to the HYTRAN program so that the hydraulic system response could be predicted throughout the maneuver. Predicted hydraulic system pressures and control-surface positions from the HYTRAN simulation of the maneuver were compared to flight-test data and were found to be in excellent agreement. The successful coalescence of the two independent software programs gives engineers a concurrent design/analysis tool that can be used to optimize hydraulic system designs during the very early stages of design.