TM 1-1510-225-10 2-58 a.   Engine Instruments   R . (1)   Interstage     Turbine     Temperature     (ITT) Indicators.    The  two  ITT  gauges  on  the  instrument panel  are  calibrated  in  degrees  Celsius  (C).    Each gauge is connected to thermocouple probes located in the   hot   gases   between   the   turbine   wheels.       The gauges indicate the temperature between the compressor turbine and power turbine section for the corresponding   engine.      Individual   5-ampere   circuit breakers, placarded ITT LEFT / RIGHT, located on the left sidewall circuit breaker panel, protect the interstage turbine temperature gauge circuits. (2)   Engine Torquemeters.  Two torquemeters on  the  instrument  panel  indicate  torque  in  percent  of maximum  being  applied  to  the  propeller  shaft  of  the respective engine. Individual     5-ampere circuit breakers, placarded  TORQUE  LEFT  /  RIGHT located on  the  left  sidewall  circuit  breaker  panel,  protect  the torquemeter's circuits. (3)   Turbine Tachometers.  Two tachometers on  the  instrument  panel  indicate  compressor  turbine RPM (N₁)  for the respective engine as a percentage of maximum  gas  generator  RPM.    Each  instrument  is slaved   to   a   tachometer   generator   attached   to   the respective engine. Individual     5-ampere circuit breakers, placarded  TURBINE  TACH  LEFT  /  RIGHT, located   on   the   left   sidewall   circuit   breaker   panel, protect the turbine tachometer circuits. (4)   Fuel Flow Indicators.  Two gauges on the instrument     panel     indicate     the     race     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.    Individual  5-ampere circuit    breakers,    placarded    FUEL    FLOW    LEFT    / RIGHT   located   on   the   left   sidewall   circuit   breaker panel, protect fuel flow indicator circuits. (5)   Oil Pressure / Oil Temperature Indicators.   Two   gauges   on   the   instrument   panel   indicate   oil pressure in psi and oil temperature in °C.  Oil pressure is taken from the delivery side of the main oil pressure pump.        A    thermal    sensor    unit    that    senses    the temperature of the oil as it leaves the delivery  side of the oil pressure pump transmits oil temperature.  Each gauge    is    connected    to    pressure    and    temperature transmitters installed on the respective engine.   Individual   5-ampere   circuit   breakers,   placarded   OIL PRESS  LEFT  /  RIGHT,  located  on  the  left  sidewall circuit  breaker  panel  protect  the  oil  pressure  circuits.   Individual   5-ampere   circuit   breakers,   placarded   OIL TEMP   LEFT   /   RIGHT,   located   on   the   left   sidewall circuit    breaker    panel,    protect    the    oil    temperature circuits. b.  Engine Instruments  T3  . (1)   Two  ITT  gauges  on  the  instrument  panel are   calibrated   in   C.    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,   3   1/2   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   Celsius.      The   display   will contain   dashes   (-----)    when    the    measured    ITT    is greater than 1200  Celsius.  When the EXCEEDENCE ITT  value  is  displayed  the  actual  measured  value,  not the dashes, will be displayed up to 1372 Celsius. The   indicator   is   equipped   with   a   Built-In   Test (BIT) display that will display all active LCD segments for 3 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. NOTE Pressing the EXCEEDENCES ERASE switch for 0.2 seconds or longer will cause all  events  to  be  erased  from  non-volatile memory in all engine instruments.  There is no  provision  for  erasing  individual  events from individual system gauges.  The   event   display   will   take   precedence   over normal  digital  display.   The  bar  graph  will  continue  to