The prototype 501F engine was built by MHI at its Takasago manufacturing and testing facilities. In mid-1989 it was reported in the press that the prototype unit would be undergoing full-load factory testing. The first 501F gas turbines (4 of them) were sold to Florida Power & Light Co. for the Lauderdale Station repowering project, and went into service in 1993. This was the first of several large repowering projects undertaken by the Florida utility, most of which used Westinghouse gas turbines (or Siemens gas turbines, following the Siemens acquisition of Westinghouse PGBU in 1998, below.)