OPERATING PRINCIPLES
Figure 7-1 illustrates that the air entering the
front frame through the nacelle air inlet is di-
rected to the compressor at the proper angle
by the guide vanes. The air pressure is in-
creased by a diffusion process as it passes
through the eight-stage compressor.
The high-pressure air leaving the compressor
is directed rearward through the mainframe to
the combustion section. A large portion of this
airflow is used for cooling and bearing seal
pressurization. A precise volume of the airflow
enters the combustion chamber where fuel is
added by the nozzles. The mixture is ignited
by the high-energy igniter plugs. The accel-
eration and expanding gases flow rearward
toward the turbine. The two-stage turbine ex-
tracts sufficient energy from the gases to drive
the compressor and the accessories. The re-
maining energy is directed through the ex-
haust to the atmosphere to provide the
propulsive force for the airplane.
ENGINE SYSTEMS
GENERAL
The engine systems include the oil system, fuel
system, ignition system, engine power control,
engine instrumentation, engine starting, engine
synchronizing, and the thrust reverser system.
OIL SYSTEM
General
The oil system utilizes a pressurized, closed-
circuit, recirculating, dry sump system de-
signed to furnish lubricating and cooling oil to
the necessary rotating components during en-
gine operation. After circulating to those parts
requiring lubrication, it drains to the sumps
where it is scavenged by individual elements
within the pump and returned to the oil tank.
Oil Tank
The oil is contained in an engine-mounted tank
that includes a dwell chamber for deaerating the
oil, a filler port and dipstick, a vent relief valve,
and overboard vent line. Tank capacity is four
quarts, and the dipstick is marked in pints.
An access (Figure 7-7) is provided on the na-
celle for oil level checking and servicing.
Oil Pump
The oil pump contains a pressure element and
five scavenge elements and is attached to the ac-
cessory gearbox. The tachometer generator is at-
tached to and driven by the oil pump. All
scavenge oil from the pump is discharged into
the oil tank dwell chamber. Lube oil from the oil
tank enters the pressure element through a pen-
dulum-type swivel pickup tube. It is delivered
by the pressure element directly to the oil cooler,
through the oil filter, and into the gearbox where
it is distributed throughout the system.
7-8
FOR TRAINING PURPOSES ONLY
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