TM 1-1510-225-10 2-61 c.   Engine   Instruments   F3   .      Engine   instru- ments, located on the left of the center position of the instrument    panel,    are    grouped    according    to    their function.          At     the     top,     the     ITT     indicators     and torquemeters  are  used  to  set  takeoff  power.    Climb and cruise power are established with the torquemeters and propeller tachometers while observing  ITT  limits.    Gas  generator  (N₁) operation is monitored   by   the   gas   generator   tachometers.      The lower grouping consists of the fuel flow indicators and the oil pressure/temperature indicators. (1)   The  ITT  indicator  gives  an  instantaneous reading    of    engine    gas    temperature    between    the compressor  turbine  and  the  power  turbines.    This  ITT reading is self-generating. (2)   The   torquemeters   give   an   indication   of foot-pounds  of  torque  being  applied  to  the  propeller. The    instruments    are    powered    by    26    Vac    power through  the  left  and  right  torquemeter  circuit  breakers respectively, located on the right side panel. (3)   The  N₁  or  gas  generator  tachometer  is read    in    percent    of    RPM,    based    on    a    figure    of 37,500 RPM    at    100%.    Maximum    continuous    gas generator  speed  is  limited  to  38,100  RPM  or  101.5% N₁. Both readings are self-generating. (4)   Oil pressure and temperature are indicated  on  two  gauges,  one  for  the  left  engine  oil pressure  and  temperature  and  an  identical  gauge  for the right engine.  These dc gauges are powered by the No. 1 and No. 2 dual feed buses respectively, and are protected by 5-ampere circuit breakers, placarded OIL PRESS and  OIL  TEMP,  located  on  the  right  sidewall circuit breaker panel. (5)   Two  gauges  indicate  the   rate  of  flow  for consumed fuel as measured by sensing units coupled into the fuel supply lines for each engine. The fuel flow indicators  are  calibrated  in  increments  of  hundreds  of pounds per hour.  The left engine indicator is powered by the No.1 dual feed bus and the right is powered by the No, 2 dual feed bus.  Both indicators are protected by 5-ampere circuit breakers, placarded  FUEL FLOW, located on the right sidewall circuit breaker panel. Proper   observation   and   interpretation   of   these instruments provide an indication of engine performance and condition. 2-31.  ENGINE TREND MONITOR. a.   General   Description.      The   Engine   Trend Monitor  (ETM)  is  a  monitoring  system  that  monitors and  records  data  on  engine  and  airframe  parameters, e.g.,  fuel  used,  cycle  counts,  total  hours,  and  engine and   airframe   exceedences.      It   provides   automatic cycle  and  engine  start  counting  and  automatic  data collection.  The ETM provides maintenance personnel with  a  complete,  accurate,  and  detailed  record  of  the engine    and    airframe    use.        At    the    time    of    first installation  of  the  ETM  in  the  aircraft,  the  data  in  the ETM   is   revised   with   the   current   pertinent   statistical data  concerning  the  airframe  and  engines.    The  ETM can   also   serve   as   a   log   that   will   contain   detailed records of each event in a  flight from power on, engine starts to engine stops, and power off. NOTE When the ETM system is inoperative, pilots are    responsible    for    manually    recording engine trend data. b.  System and Related Components. (1)   The   ETM   Processor.       The   processor contains the main computer, and is the collection point for data received from the various engine transducers. (2)   The   Airdata   Computer.      T3      F3   The Airdata  computer  provides  airdata  calculations  and  is   interfaced   to   the   KLN90B   GPS   receiver.      R   The Airdata  computer  provides  airdata  calculations  and  is the interface to the GNS -XLS FMS. (3)   The    Display    &    Key    Recorder.        The Display and Key Recorder is a cabin-mounted display that   houses   both   the   key   recorder   equipment   and display interface. (4)   Indicator Light.  An indicator light, labeled ETMS,  is  located  on  the  right  side  of  the  instrument panel below the stormscope.  The  ETMS indicator light illuminates  when  the  ETM  is  recording  data  and  for 10 seconds after the master switch is turned on. c.   Normal    Operations.        When    the    master switch   is   turned   on,   power   is   applied   to   the   ETM causing the  ETMS indicator light to illuminate and the ETM  to  perform  a  self-test.    It  is  vital  that  the  pilot follow    certain    procedures    when    starting    up    and shutting   down   the   aircraft   in   accordance   with   the following: (1)   When   starting   the   aircraft,   wait   a   full 10 seconds before starting the engines after turning on the  master  switch  to  allow  the  ETM  to  complete  its startup procedures. (2)   If the engines are started before the ETM has  completed  its  startup  sequence,  the  system  will not   record   any   engine   starts.      This   will   result   in inaccurate  cycle  counts,  engine  start  counting,  and trend analysis.