TM 1-1500-204-23-3
CHAPTER 2
FUEL SYSTEMS
2-1. General. The fuel system supplies fuel to the
carburetor or fuel control under all conditions of ground
and air operation. Identification, contamination, and
general maintenance practices will be covered in this
chapter.
2-2. Safety Precautions and Procedures. The safety
precautions and procedures below are only minimum
requirements for average conditions. All personnel who
are required to service, maintain, or repair fuel systems
should observe the precautions described in the following
paragraphs.
a.
Fuel Lines and Drains. Keep all fuel vents and
drains clean and open.
b.
Tools. Use only sparkproof hand or air power
tools in the maintenance of fuel systems.
c.
Tool Boxes. Rubber wheeled tool boxes inside
the fuel cell repair area shall be bonded to the
aircraft and grounded. Tool boxes, except those
mounted on rubber wheels, shall remain outside
the fuel cell repair area. Tools required to
perform maintenance shall be hand-carried to the
aircraft
in
nonmetallic
containers,
such
as
cardboard boxes or canvas bags. Tool boxes
locked and secured in storage racks need not be
removed from the fuel cell repair area providing
they remain locked and in the storage racks.
d.
Work Stands. All work stands shall be equipped
with a personnel static discharge plate made of
copper, zinc or zinc coated material, or other non-
oxidizing material. The plate shall be welded to
the handrail, at entrance to the stand, so
personnel can contact it before coming in contact
with the aircraft. The plate shall be marked
"PERSONNEL STATIC DISCHARGE PLATE."
Work stands inside the fuel cell repair area shall
be bonded to the aircraft or grounded. Properly
installed and maintained ground reels located on
the work stand bases can be used.
WARNING
Plastic or polyethylene buckets
shall not be used for collecting or
storing fuel. They cannot be
grounded.
e.
Drain Containers. Approved metal containers or
bowsers shall be used to catch running fuel.
When metal containers are used, they shall be
bonded to the aircraft and grounded. When not in
use, they shall be grounded at all times. Only
approved containers shall be used to drain small
amounts of residual fuel.
CAUTION
Personnel approaching an aircraft
for fuel system maintenance shall
ground themselves to remove static
electricity.
f.
Personnel. Before entering a fuel system repair
area all personnel shall dispose of all lighted
cigarettes, cigars, pipes, and any spark/flame
producing device, such as matches or lighters on
their person.
2-3. Fuel Identification. Turbine fuel and Aviation
Gasoline
(AVGAS)
identification
and
volatility
are
explained in the following paragraphs. Additional
information can be found in TB 55-9150-200-24.
a.
Turbine Fuels. Two types of jet fuel are in
common use. Jet A (JP-5) is a heavy kerosene
having a higher flash point and lower freezing
point than most kerosenes. It has a very low
vapor pressure, so there is little loss of fuel from
evaporation or boil off at higher altitudes. Jet B
(JP-4) is a blend of gasoline and kerosene. JP-4
is the Army standard fuel for turbine engines.
The difference in the specific gravity of the fuels
may require fuel control adjustments. Therefore,
the
fuels
cannot
always
be
considered
interchangeable. The critical characteristics of jet
fuels JP-4 and JP-5 are shown in table 2-1.
(1)
Turbine fuel identification. Because turbine
fuels are not dyed, there is no on-sight identification for
them. They range in color from a colorless liquid to a
straw-colored liquid, depending on age or the crude
petroleum source.
(2)
Turbine fuel volatility. One of the most
important characteristics of turbine fuel is its volatility. A
high volatility is desirable to aid cold-weather starting and
to make aerial restarts easier and more sure. Low
volatility is desirable to reduce the possibility of vapor lock
and to reduce fuel loss by evaporation. Figure 2-1 shows
the vaporization characteristics of aviation fuels at
atmospheric pressure.
2-1
