TM 1-1510-218-10 2-49 respective propeller reduction gear case.   Torquemeters  are  protected  by  individual  0.5  ampere circuit   breakers,   placarded   TORQUEMETER   #1   or TORQUEMETER  #2, on the overhead circuit breaker panel. 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 engine. 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 panel. 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 seconds. (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 recorded.