air control valve and into the ship's bleed air
The solenoid valve is located in the line
system. The control valve receives signals from
between the speed-sensitive valve and the bleed
the LOCOP for operation. If the TIT reaches
air valves. When activated, it routes ship's service
1870F, the bleed air control valve will close to
air to hold the 5th- and 10th-stage bleed air valves
maximize the amount of cooling air to the turbine
closed. It is used during a fire stop or while the
and maintain the TIT in the range of 1850F to
engine is water washed.
1870F. A manual switch, 14TH-STAGE
BLEED, is located on the LOCOP. It allows you
ENGINE FUEL SYSTEM
to enable the bleed air control circuit. When this
switch is in the ON position, the bleed valve will
The fuel system meters and distributes fuel to
open at 12,780 rpm. It is then fully automatic with
the engine. This system is used to maintain a
respect to TIT. The 14th-stage bleed air valve will
constant generator rotor speed under varying load
also close when the engine speed drops below
conditions. Components of the fuel system are
12,780 rpm.
both engine mounted and off-engine mounted.
The model 139 LOCOP bleed air selector
The engine-mounted components on the
switch also has a remote position. When the
model 104 GTGS (fig. 3-18) include the following
switch is placed in remote, the control of the 14th-
parts: a dual-element fuel pump (1), an LP fuel
stage bleed air valve is transferred to a control
filter (2), an HP fuel filter (3), a pressure relief
panel in CCS.
valve (4), a liquid fuel valve (LFV) (5), an
electrohydraulic (electric) governor (EG) actuator
Fifth- and Tenth-Stage Bleed Air
(6), a fuel shutoff valve (7), a manifold drain valve
This system has eight pneumatically operated
(8), fuel nozzles (9), and burner/combustor drain
bleed air valves, a speed-sensitive valve, a filter,
valves (10).
and a three-way, solenoid-operated valve. Four
Off-engine mounted components of the model
bleed air valves are mounted on each of the 5th-
104 are a temperature-biased compressor inlet
stage and the 10th-stage bleed manifolds. These
temperature (CIT)/compressor discharge pressure
valves are piston-type valves, with 5th- and 10th-
(CDP) sensor (11), the governor control unit
stage air pressure on the inboard side of the valve.
(GCU) (not shown), and a start temperature limit
Either atmospheric pressure or 14th-stage air
control valve (12). The model 104 uses the
pressure is routed to the outboard side.
Woodward 2301 governor control system.
The speed-sensitive valve is engine driven. It
The model 139 fuel system (fig. 3-19) is slightly
is mounted on the left forward side of the AGB.
different from the model 104 fuel system. Both
The valve has three ports. One port receives 14th-
models incorporate an engine-mounted fuel
stage air via a pipe from the diffuser. A second
divider (1), two manifold drain valves (one
port is piped to the outboard side of the 5th- and
manifold drain valve on the model 104) (2), dual-
10th-stage bleed air valves. The third port is
entry fuel nozzles (3), and two fuel manifolds (4).
vented to the atmosphere. During operation at
Refer to your ship's technical manuals for the
engine speeds below 12,780 rpm, a pilot valve in
system used on your ship.
the speed-sensitive valve blocks 14th-stage air.
The governor system on the model 139 is the
This allows the outboard side of the 5th- and 10th-
Woodward 9900-302 governor control system. For
stage bleed air valves to be vented to the
this adaption the engine is fitted with an electrical
atmosphere (through the third port on the speed-
CIT sensor, mounted in the air inlet housing, a
magnetic speed pickup, and a LFV-mounted
sensitive valve). Since 5th- and 10th-stage air
linear variable displacement transformer (LVDT)
pressure is greater than atmospheric pressure, the
valves open and vent air from the compressor. At
(5).
engine speeds above 12,780 rpm, the pilot valve
closes the vent port. This allows 14th-stage air to
Model 104 Fuel System Flow Path
be ported to the outboard side of the 5th- and
10th-stage bleed air valves. Since 14th-stage air
The following paragraph describes the fuel
pressure is greater than 5th- and 10th-stage air
flow path through the fuel system of the model
104. Refer to figure 3-18 as we describe the
pressure, the valves close and bleed air is stopped.
The filter is located in the 14th-stage air line
operation.
Fuel from a gravity feed tank enters the
from the diffuser to the speed-sensitive valve. It
enclosure through an external emergency shutoff
prevents contaminants in the air from clogging
valve and flows into the inlet of the fuel pump.
the valve.
3-21
