Rolls-Royce has exercised its option to add Parker Aerospace's heat-management valves to the pneumatics package it already supplies on the Trent XWB engine program. Product design, manufacture, and support will be completed by the Parker Aerospace Fluid Systems Division in Irvine, CA. The heat-management-valve package will include a surface-air oil-heat exchanger oil bypass valve (OBV) and variable-frequency generator surface-air cooled-oil-cooler thermal bypass valve (TBV). The OBV is required to maintain the engine lubrication oil and fuel temperatures within defined limits contributing to optimum engine performance. The TBV is installed in each variable-frequency generator oil circuit on the engine to avoid overcooling the oil.