2013 MARCH / Vol. 5 / No. 3 /
GA
25
internationally agreed standard, has
a flash point above 38°C (100°F)
and a freeze point maximum of
-47°C. It is widely available outside
the U.S.A. Jet A-1 meets the
requirements of British specification
DEF STAN 91-91 (Jet A-1),
(formerly DERD 2494 (AVTUR)),
ASTM specification D1655 (Jet
A-1) and IATA Guidance Material
(Kerosine Type), NATO Code F-35.
JET A
Jet A is a similar kerosene type of fuel,
produced to an ASTM specification
and normally only available in the
U.S.A. It has the same flash point as Jet
A-1 but a higher freeze point maximum
(-40°C). It is supplied against the
ASTM D1655 (Jet A) specification.
JET B
Jet B is a distillate covering the
naphtha and kerosene fractions. It
can be used as an alternative to Jet
A-1 but because it is more difficult to
handle (higher flammability), there is
only significant demand in very cold
climates where its better cold weather
performance is important. In Canada
it is supplied against the Canadian
Specification CAN/CGSB 3.23
MILITARY JP-4
JP-4 is the military equivalent of
Jet B with the addition of corrosion
inhibitor and anti-icing additives; it
meets the requirements of the U.S.
Military Specification MIL-
DTL-5624U Grade JP-4. (As of
Jan 5, 2004, JP-4 and 5 meet the
same US Military Specification).
JP-4 also meets the requirements
of the British Specification
DEF STAN 91-88 AVTAG/FSII
(formerly DERD 2454),where
FSII stands for Fuel Systems Icing
Inhibitor. NATO Code F-40.
JP-5
JP-5 is a high flash point kerosene
meeting the requirements of the
U.S. Military Specification MIL-
DTL-5624U Grade JP-5 (as of Jan
5, 2004, JP-4 and 5 meet the same
US Military Specification). JP-5
also meets the requirements of the
British Specification DEF STAN
91-86 AVCAT/FSII (formerly
DERD 2452). NATO Code F-44.
JP-8
JP-8 is the military equivalent of Jet
A-1 with the addition of corrosion
inhibitor and anti-icing additives;
it meets the requirements of the
U.S. Military Specification MIL-
DTL-83133E. JP-8 also meets
the requirements of the British
Specification DEF STAN 91-87
AVTUR/FSII (formerly DERD
2453). NATO Code F-34.
AVIATION FUEL ADDITIVES
Aviation fuel additives are compounds
added to the fuel in very small
quantities, usually measurable only
in parts per million, to provide
special or improved qualities. The
quantity to be added and approval
for its use in various grades of
fuel is strictly controlled by the
appropriate specifications.
A few additives in common
use are as follows:
1. Anti-knock additives reduce
the tendency of gasoline to
detonate. Tetra-ethyl lead (TEL)
is the only approved anti-knock
additive for aviation use and has
been used in motor and aviation
gasolines since the early 1930s.
2. Anti-oxidants prevent the formation
of gum deposits on fuel system
components caused by oxidation
of the fuel in storage and also
inhibit the formation of peroxide
compounds in certain jet fuels.
3. Static dissipater additives reduce
the hazardous effects of static
electricity generated by movement
of fuel through modern high
flow-rate fuel transfer systems.
Static dissipater additives do not
reduce the need for `bonding'
to ensure electrical continuity
between metal components (e.g.
aircraft and fuelling equipment)
nor do they influence hazards
from lightning strikes.
4. Corrosion inhibitors protect
ferrous metals in fuel handling
systems, such as pipelines and
fuel storage tanks, from corrosion.
Some corrosion inhibitors also
improve the lubricating properties
(lubricity) of certain jet fuels.
5. Fuel System Icing Inhibitors (Anti-
icing additives) reduce the freezing
point of water precipitated from
jet fuels due to cooling at high
altitudes and prevent the formation
of ice crystals which restrict the
flow of fuel to the engine. This
type of additive does not affect the
freezing point of the fuel itself.
Anti-icing additives can also
provide some protection against
microbiological growth in jet fuel.
6. Metal de-activators suppress
the catalytic effect which some
metals, particularly copper,
have on fuel oxidation.
7. Biocide additives are sometimes used
to combat microbiological growths
in jet fuel, often by direct addition
to aircraft tanks; as indicated above
some anti-icing additives appear
to possess biocidal properties.
8. Thermal Stability Improver additives
are sometimes used in military JP-8
fuel, to produce a grade referred
to as JP-8+100, to inhibit deposit
formation in the high temperature
areas of the aircraft fuel system. ·
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