Table 2-1. Critical Characteristics and Specification Requirements

TM 1-1500-204-23-3 b. Aviation Gasoline. AVGAS is a mixture of hydrocarbons. AVGAS grades which conform to MIL-G- 5572 are used to power reciprocating engine aircraft. Although various AVGAS grades are available, grade 100/130 (green or blue) is the grade most used by the Army. AVGAS permits high-compression, supercharged engines to develop maximum power without pre-ignition (knocking). The Army requirement for AVGAS is decreasing and will be eliminated as reciprocating-engine aircraft are phased out of the Army inventory. Detailed guidance on specification requirements for aviation gasoline is included In MIL-HDBK-200 (latest revision) and FM 10-70. (1) AVGAS identification. AVGAS is colored for purposes of identification. A change in color usually indicates contamination with another product or loss of fuel quality. Table 2-2 shows various AVGAS grades and their identifying colors. (2) AVGAS volatility. Volatility is a measure of the tendency of a liquid to vaporize. AVGAS is a complex blend of volatile hydrocarbons that have a wide range of boiling points and vapor pressures. It is blended to form a straight chain of boiling points. This is necessary to obtain the required starting, acceleration, power, and fuel mixture characteristics for the engine. Vaporization characteristics are shown in figure 2-1. Table 2-1. Critical Characteristics and Specification Requirements for Jet Fuels Used In Army Aircraft (MIL-T-5624)1 Characteristic Specification Test method requirement ASTM Flash Point, °C (F), min Grade JP-4 Grade JP-5 60 (140) D93 Specific Gravity, °C Grade JP-4 0.785 Grade JP-5 0.817/15 Specific WT/U.S. gal Grade JP-4 6.55 Grade JP-5 6.82 FSII, percent vol. 0.10-0.15 Gravity, °API D287 Grade JP-4 57-45 Grade JP-5 48-36 Freezing Point, °C, max D2386 Grade JP-4 -58 Grade JP-5 -46 Flash Point, °C, min D56 or Grade JP4 ¾ D3243 Grade Jp-5 60 1Detailed specification is included in MIL-HDBK 200 (latest edition) and FM 10-70. 2-2