Powerplant
Citation Bravo Developed for Training Purposes 5L-11
March 2009
CAE SimuFlite
Lubrication System
Ignition System
5L-12
Turbine Speed (N
2
)
The N
2
speed sensor is located on
the accessory gearbox right-hand
side. the sensor is directed at the
teeth of the FCU drive gearshaft that
is geared to the HP rotor via the
accessory drive gearshaft and tower
shaft. The resulting voltage is trans-
mitted to the aircraft cockpit instru-
mentation via the main control
harness. The N
2
signal is also used
by the bleed valve control to com-
pute correct bleed valve position.
The turbine speed indicator (
Figure
5L-4)
is a dual-reading digital dis-
play that indicates speed as a per-
centage of maximum RPM. Each
three digit display shows N
2
RPM to
0.1%. At the maximum turbine
speeds of 100% N
2
RPM, the digits
and a red light flash as warning.
The tachometer/generator and indi-
cator operate on 28 VDC from the
normal electrical system. The Left
Main Extension bus powers the left
engine indicator though the LH
TURB SPEED circuit breaker; the
Left Crossover bus powers the right
indicator though the RH TURB
SPEED circuit breaker. If either
indicator loses power, the respective
display blanks.
Interturbine Temperature
(ITT)
The ITT gauge (Figure 5L-4, previ-
ous page) provides a synthetic or
calculated indication of engine Inter-
turbine Temperature (ITT). A series
of Chromel/Alumel
temperature probes and thermocou-
ples sense temperature in the bypass
duct, low compressor case, and
exhaust nozzle.
T
1
thermocouples in the inlet and
exhaust area. The bypass duct pro-
vide an average temperature reading
equal to three times the temperature
rise though the bypass duct. T
6
ther-
mocouples in the leading edges of
the exhaust case nozzle struts con-
nects in parallel to provide an aver-
age temperature reading of the gas
stream exiting the turbine section.
The ITT indicating system adds the
temperature rise sensed by the T
1
thermocouples to the T
6
temperature
to provide a simulated temperature.
The dual vertical scale ITT gauge on
the top left center of the instrument
panel displays left and right engine
temperature. The vertical tape dis-
plays ITT from 200° to 750°C. A
green band from 200° to 750°C. A
green band from 200° to 700°C indi-
cates normal operating range of the
engine. A red radial line at 700°C
denotes the maximum takeoff and
start ITT. The gauge also includes a
red triangle at 740°C.
The indicator operates on 28 VDC
for the normal electrical system. The
left engine ITT tape receives power
from the Left Main Extension bus
through the LH ITT circuit breaker;
the right engine indicator receives
power from the Left Crossover bus
though the RH ITT circuit breaker. If
the indicator loses 28 VDC, a red
OFF flag appears above the respec-
tive tape display.
Turbine Speed (N
2
) Limita-
tions Citation Bravo
Takeoff (5 minutes) . . . . . . . . 100%
Maximum Continuous . . . . . . 100%
Ground Idle Continuous. . . . .45.3%
Flight Idle Continuous . . . . . . 49.4%
Transient (20 seconds) . . . . . . 102%
ITT Limitations
Takeoff (5 minutes . . . . . . . . 700°C
Max. Continuous. . . . . . . . . . 700°C
Starting (2 seconds) . . . . . . . 740°C
Transient (20 seconds) . . . . . 740°C
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