MIL-DTL-5624 Turbine Fuel, Aviation, Grades Jp-4 And Jp-5This specification covers two grades of aviation turbine fuel NATO F-40 \(JP-4\) and NATO F-44 \(JP-5\) \(see 6.1\). Synthesized hydrocarbons from new sources require specific guidance that is outside the scope of MIL-DTL-5624. This guidance is found in ASTM D7566.