Since Westinghouse corporate support of advanced gas turbine development and design at that time was nil, Westinghouse agreed to supply key engine design engineering support (as specified by MHI) and MHI provided the funding to support the effort, as well as to manufacture the prototype engine. Joint conceptual design started in mid-1986 and, somewhere early in the effort, it was decided that the first engine should be the 60 Hz "501F" version of the design. (MHI would subsequently complete the scaling process for the 50 Hz design.) The new design provided both companies with the opportunity to incorporate some important design improvements and attributes that were not feasible to be back-engineered into existing W501D5/MW701D designs, but could readily be introduced into a new design.