Abstract : This report covers a study of the effects of broadening the specifications for JP-4 and JP-8, by increasing the freeze point, decreasing the smoke point, and extending the end point on minimizing costs and maximizing fuel availability. The study considered the impact on the engines and airframes. It was concluded that the specification maximum allowable freeze point of JP-4 or JP-8 could not be increased without degrading aircraft system performance and safety on the basis of criteria available to this study. Increases in availability were predicted for JP-4 of up to 9% and for JP-8 between 41% and 62%. A fuel price analysis was performed based on prices through 1978. Price changes subsequent to the analysis have been so rapid and so unbalanced between products that predictions cannot be made of price changes resulting from specification changes. (Author)