exceedence N2. The bar graph display has a range of
0 to 2500 RPM.
The digital display will contain dashes (------)
when the measured N2 is greater than 2500 RPM.
When displaying exceedence N2 values, the actual
measured value, not "-----", will be displayed up to
4000 RPM. The dashes will be prefixed with an F if an
EEPROM failure has been detected and with an E if
an event has been stored and not played back.
The indicator performs BIT on the LCD display,
ROM (program memory), RAM (volatile data memory),
EEPROM (non-volatile data memory), and input
signal. The display BIT shall consist of displaying all
active LCD segments for 3 seconds on powerup. If
the ROM or RAM fails BIT the indicator display will be
blank. If the input signal fails BIT the indicator will
display 0 on both the digital and bar graph displays. If
the EEPROM fails BIT the indicator will prefix the
digital display with an F. BIT failures are not stored in
EEPROM. Failures detected shall therefore not affect
the display after power is cycled unless the failure is
Each exceedence event will consist of two 16-bit
words. One word will contain the peak RPM
measured during the event and the other word
contains the event duration in seconds. A maximum of
50 events can be recorded. If more than 50 events
are recorded, only 50 will be stored. As new events
are recorded, the oldest events will be discarded. The
indicator will prefix the digital display with an E when
an event is being or has been recorded and not played
The indicator will start recording an event
immediately when the indicator has measured RPM
greater than 2200 or when the indicator has measured
RPM above 2081 continuously for five seconds. The
indicator display will start flashing whenever the
measured RPM exceeds 2081. The flashing will
cease and digital display will be prefixed with an E
when the indicator begins recording an exceedence.
The indicator will end exceedence recording and store
the event when the measured RPM drops to 2080 or
Pressing the EXCEEDENCE ERASE switch
for 0.2 seconds or longer will cause all
events to be erased from non-volatile
memory. There are no provisions for
erasing individual events.
The event display takes precedence over normal
digital display. The bar graph will continue to display
current N2 data. To activate the event display, press
the EXCEEDENCE DISPLAY switch for 0.2 seconds
or longer. The most recent event will be displayed
first. Each event display contains the following cycle:
1. The event number will be displayed for 2
2. The event peak RPM will be displayed for
3. The event duration in seconds will be
displayed for 2 seconds.
All three data items displayed during playback
will be prefixed with a P unless an EEPROM BIT
failure has been detected in which case the display will
be prefixed with an F.
The event display will be terminated after all of
the recorded events have been displayed. Once the
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 recorded.
Section VII. UTILITY SYSTEMS
2-51. DEFROSTING SYSTEM.
a. Description. The defrosting system is an
integral part of the heating and ventilation system.
The system consists of two warm air outlets connected
by ducts to the heating system. One outlet is just
below the pilot's windshield and the other is just below
the copilot's windshield. A push-pull control, placarded
DEFROST AIR, on the pilot's subpanel, manually
controls airflow to the windshield. When the control is
pulled out, defrosting air is ducted to the windshield.
As the control is pushed in, there is a corresponding
decrease in airflow.
b. Automatic Operation.
1. VENT BLOWER Switches As required.
2. CABIN TEMP MODE Switch AUTO.
3. CABIN TEMP Rheostat As required.