Torquemeters are protected by individual 0.5 ampere
circuit breakers, placarded TORQUEMETER #1 or
TORQUEMETER #2, on the overhead circuit breaker
c. Turbine Tachometers. Two tachometers on
the instrument panel register compressor turbine RPM
(N1) for the respective engine. These indicators
register turbine RPM as a percentage of maximum gas
generator RPM. Each instrument is slaved to a
tachometer generator attached to the respective
d. Oil Pressure/Oil Temperature Indicators.
Two gauges on the instrument panel register oil
pressure in psi and oil temperature in °C. Oil pressure
is taken from the delivery side of the main oil pressure
pump. Oil temperature is transmitted by a thermal
sensor unit, which senses the temperature of the oil as
it leaves the delivery side of the oil pressure pump.
Each gauge is connected to pressure transmitters
installed on the respective engine. Both instruments
are protected by 5-ampere circuit breakers, placarded
OIL PRESS # 1, OIL PRESS # 2, OIL TEMP #1, and
OIL TEMP #2, located on the overhead circuit breaker
e. Fuel Flow Indicators. Two gauges on the
instrument panel, Figure 2-17, register the rate of flow
for consumed fuel as measured by sensing units
coupled into the fuel supply lines of the respective
engines. The fuel flow indicators are calibrated in
increments of hundreds of pounds per hour. Both
circuits are protected by 0.5-ampere circuit breakers,
placarded FUEL FLOW #1 or FUEL FLOW #2,
located on the overhead circuit breaker panel.
2-39. ENGINE INSTRUMENTS T .
a. Turbine Gas Temperature Indicators. Two
Interstage Turbine Temperature (ITT) gauges on the
instrument panel are calibrated in degrees Celsius.
Each gauge is connected to thermocouple probes
located in the hot gases between the turbine wheels.
The gauges register the temperature present between
the compressor turbine and power turbine for the
corresponding engine. The indicator display is a 1
alphabetic, 3½ numeric character digital display and a
41-segment bar graph display. The bar graph display
is nonlinear. The indicator has a display range of 0 to
1200 °C while displaying current ITT and 0 to 1372 °C
while displaying exceedence ITT. The bar graph
display ranges from 0 to 1200 °C. The display will
contain dashes (----) when the measured ITT is greater
than 1200 °C. When the exceedence ITT value is
displayed the actual measured value, not the dashes,
will be displayed up to 1372 °C.
The indicator is equipped with a Built In Test
(BIT) display that will display all active LCD segments
for three seconds on power up. If the BIT test detects
a failed ROM or RAM, the BIT indicator will have a
blank display. If the BIT failure is the input signal, a
"0" will be displayed on both the digital and bar graph
displays. If the failed BIT is caused by the EEPROM
an "F" will prefix the display. BIT failures will not be
stored in EEPROM. Once power is reapplied the
previous failures detected will not affect the display.
When a limit is exceeded, an exceedence event
will be stored in the EEPROM memory. All event
records will consist of two words. One word will
contain the peak temperature measured during the
event with a resolution of 1 °C. The other word will
contain the event duration in seconds with a resolution
of 1 second. A maximum of 50 events will be
recorded. If more than 50 events are recorded, the
new event will be recorded and the oldest event shall
be discarded. The prefix "E" will be displayed when an
event is being or has been recorded and not played
back. The digital display will start flashing whenever a
temperature limit has been exceeded. The flashing
will cease and the display prefixed with an "E" when
the time/temperature combination is exceeded and an
exceedence is being recorded.
The event display will take precedence over
normal digital display. The bar graph will continue to
display current ITT data. To activate the event display,
hold the EXCEEDENCE DISPLAY switch for 0.2
seconds or longer. The events will be displayed in
reverse chronological order (most recent event first).
All event displays will consist of the following cycle:
(1) A two-digit event number display for
(2) The event peak temperature values in
degrees Celsius displayed for 2 seconds.
(3) The event duration, in seconds, displayed
for 2 seconds.
All three data items displayed during playback
shall be prefixed with a "P" if the event was recorded
in a non-start mode or an "S" if the event was recorded
in the start mode.
Once an event playback sequence has been
performed the "E" prefixed to the digital display will be
removed. All event data is still available for playback
until the data is erased. The display will be prefixed
with an "E" again on the next power up cycle if the old
data has not been erased or if another event is