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.
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.
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
Flash Point, °C (F), min
Specific Gravity, °C
FSII, percent vol.
Freezing Point, °C, max
Flash Point, °C, min
1Detailed specification is included in MIL-HDBK 200 (latest edition) and FM 10-70.