solenoid-operated and may be controlled from the
function of the lube oil service pumps. The operator
initiates these commands by depressing the push-button
SSGTG local operating panel (LOCOP) or the EPCC.
indicators in the reduction gear lube section of the
The starting air system is supplied by the
propulsion mimic panel.
high-pressure air system through banks of high-pressure
The motor-driven lube oil service pump control
air flasks and the bleed air header. The bleed air system
is the normal source of starting air when gas turbines are
signals from the PACC are sent via the DMS to the
appropriate SCU computer. Two modes of motor-driven
operating. The high-pressure air system flasks are the
lube oil service pump control are available: MANUAL
starting air source when no turbines are operating or a
and AUTO LEAD. The MANUAL mode allows the
bleed air PRESS LOW alarm is set.
operator to select pump speed with OFF, LOW SPEED,
At the PACC, the operator selects the starting air
and HIGH SPEED push-button indicators. The AUTO
source by depressing the starting air BLEED or HIGH
LEAD mode also allows the operator to select pump
PRESS push-button indicator. These push buttons
speeds manually and tells the SCU computer which
interface with the starting air select computer program
pump to start first in response to the MRG hydraulically
function in the SCU computer. When the BLEED or
most remote bearing pressure. The control location
HIGH PRESS push button is depressed, a status
switch on a lube oil service pump motor controller must
message appears on the PDU. The BLEED or HIGH
be in REMOTE before the computer can control pump
PRESS signal is sent with an ON or ON LINE command
operation. Three push-button indicators at the PACC
to align the appropriate starting air valve. Valve
allow the operator to assume control of the lube oil
alignment for a BLEED or HIGH PRESS start is
pumps individually. Automatic and manual pump
initiated by the SCU engine state logic-on computer
operation are enabled when the operator depresses an
program function.
AUTO LEAD push button. AUTO LEAD prevents the
A GTE may be motored with bleed or high-pressure
operator from commanding pump speeds that contradict
the lube oil service pumps automatic mode logic. When
air using the same air paths as a bleed or high-pressure
pump control is in AUTO LEAD, the pumps cycle as a
start. The only difference is the motor air regulator valve
f u n c t i o n of the main reduction gear (MRG)
is set to the motor position by the engine state
hydraulically most remote bearing pressure. Now that
logic-motor computer program function. The motor air
we have described the lube oil system, let's go on to the
regulator valve regulates air pressure to 22 psig when it
air system.
is in the motor position. At the PACC, the operator can
start the motor sequence for a GTM in the OFF state by
depressing the MOTOR push button.
Air System
The masker air system is aligned by the HULL
MASKER ON and OFF push-button indicators at the
There are two compressed air systems associated
PACC. These push buttons operate the masker air select
with the GTEs and the GTGSs: (1) the bleed air system
computer program function in the SCU computer. The
and (2) the high-pressure air system. Let's look at the
HULL MASKER ON push button places the bleed air
bleed air system first.
transfer valve in the masker position if a GTE start or
The bleed air system contains the following four
motor command is not active in the same MER. The
distinct subsystems:
HULL MASKER OFF push button places the bleed air
transfer valve in the start/motor position. The bleed air
1. Starter air
transfer valve position is displayed on the PDU.
2. Masker air
The prairie air system is supplied with bleed air
3. Prairie air
through a prairie air cooler and supply valve in each
MER. The PRAIRIE ON and OFF push-button
4. Anti-icing air
indicators provide manual inputs to the SCU computer
The bleed air system is supplied with combustion
to issue commands to its connected prairie air supply
air extracted from each operating GTE and SSGTG
valve. When the prairie air supply valves are operated
compressor. Each GTE and SSGTG has a bleed air valve
from the PACC, the appropriate indicator illuminates
that controls the flow of air from the engine to the bleed
and a status message is displayed on the PDU.
air header. The bleed air valve for each GTE is
The anti-icing system is supplied by bleed air
motor-operated and may be controlled from the SCU or
the PACC. The bleed air valve for the SSGTG is
injected into the gas turbine intakes upstream of the
3-14
