TM 55-4920-328-13 (b)    Data   acquisition   assembly      (Unit 11).      The   data   acquisition   assembly   (figure   1-29)   is mounted   on   the   left   side   of   the   engine   test   dolly assembly.  When interconnecting cable assemblies and hose   assemblies   are   attached   from   the   control   cab module    and    from    the    engine,    the    data    acquisition assembly   acts   as   the   interface   between   the   engine being   tested   and   METS   instrumentation.      The   data acquisition    assembly    consists    essentially    of    a    data acquisition unit cutout box used to mount and house 18 electrical   connectors,   18   quick-disconnect   couplers,   3 pressure  gage  switches  S1,  S2,  and  S3,  14  pressure transmitters   MT1   through   MT14,   and   5   temperature transmitters    MT15    through    MT19.        The    unit    also contains   9   filters   used   in   fluid   pressure   circuits,   a pressure   gage,   a   pressure   regulator,   and   a   solenoid valve.        The    unit    is    also    equipped    with    19    hose assemblies,    rigid    tube    assemblies,    and    8    terminal boards  for  electrical  connection.    An  access  panel  is installed in the unit.  The panel is secured to the cutout box  with  14  flush-mounted  studs  which  engage  mating receptacles  in  the  unit.    Two  support  assemblies  are installed  on  the  bottom  face  of  the  cutout  box.    The pneumatic     and     fluid     pressure     circuits     are     shown schematically in figure 1-30. The significant components    of    the    data    acquisition    assembly    are described in the following text. 1.    Fuel  pressure  gage  switch  S1.    The  fuel pressure  gage  switch  (170,  figure  7-24)  senses  supply fuel  pressure  delivered  to  an  engine  under  test.    The switch alerts the test technician of out-of-tolerance, low fuel   pressure   by   causing   the   ENGINE   LOW   FUEL PRESSURE indicator (14A, figure 1-25) to intermittently flash  on  and  off  and  the  audible  alarm  to  sound.    Low fuel  pressure  actuates  the  switch  to  provide  a  28v  dc signal to the indicator and audible alarm unit.  When the switch senses decreasing pressure at or below 8.0 psig, the switch closes to complete the circuit to the indicator. When the switch senses increasing pressure at or above 7.0 psig, the switch opens to disrupt the circuit to cause the light to go off and silence the audible alarm. 2.    Engine  low  oil  pressure  gage  switch  S2. The  low  oil  pressure  gage  switch  (184C,  figure  7-24) senses  low  oil  pressure  to  an  engine  under  test.    The switch  alerts  the  test  technician  of  out-of-tolerance  low oil    pressure    by    causing    the    ENGINE    LOW    OIL PRESSURE  indicator  (11,  figure  1-25)  to  intermittently flash on and off and the audible alarm to sound.  Low oil pressure actuates the switch to provide a 28v dc signal to the indicator and audible alarm unit.  When the switch senses  decreasing  pressure  at  or  below  25.0  psig,  the switch  closes  to  complete  the  circuit  to  the  indicator. When the switch senses increasing pressure at or above 28.0 psig, the switch opens to disrupt the circuit to cause the light to go off and silence the audible alarm. 3.    Air   pressure   gage   switch   S3.      The   air. pressure  gage  switch  (181,  figure  7-24)  senses  hot'  air pressure  in  an  engine  under  test.    The  pressure  gage switch is a single pole double throw unit that actuates to cause a light to come on at operator's panel 3A1 in Unit 3    and    sound    the    audible    alarm.        Decreasing    air pressures  at  or  below  4.5  psig  actuates  the  switch  to complete a circuit to provide 28v dc power to illuminate the  DE-ICE  VALVE  OPEN  indicator  (10,  figure  1-24) and    sound    the    alarm.        When    the    switch    senses increasing air pressure at and above 4.0 psig, the switch opens  to  disrupt  the  circuit  and  cause  the  lamp  in  the indicator  to  go  off  and  silence  the  alarm.    This  action simultaneously completes a circuit to cause the lamp in the DE-ICE VALVE CLOSED indicator (14) to come on to  indicate  normal  operating  conditions  in  the  engine under test. 4.    Pressure    transmitters    MT1    and    MT2. Pressure  transmitters  MT1  and  MT2  (176,  figure  724) are installed in the data acquisition assembly to transmit water   brake   water   pressure   signals   to   the   WATER PRESSURE  IN  meter  (4,  figure  1-25)  and  the  WATER PRESSURE   OUT   meter   (5)   on   the   services   panel assembly.  Pressure transmitter MT1 is used in the inlet water  pressure  circuit;  the  other  is  used  in  the  outlet water   pressure   circuit.      The   two   units   are   identically constructed; therefore, only one will be described.  The pressure transmitter is an encapsulated unit approximately    3.27    inches    long    and    1.00    inch    in diameter.  The pressure port conforms to MS33656-4 to accommodate   1/4-inch   tubing.      A   6-pin   connector   is installed  on  the  opposite  end  for  connection  of  28v  dc excitation voltage and output signals to the appropriate water  brake  performance  analyzer  meter  on  the  upper panel  assembly  of  the  services  submodule.    The  full scale output range is 0 to 5v dc with an input pressure range of 0 to 250 psia at an excitation voltage of 28v dc. The  unit  consists  of  a  foil  strain  gage  bonded  to  the sensing  element  of  a  four-arm  bridge.    Output  of  the bridge   is   conditioned   by   a   printed   circuit   module   to provide   the   calibrated   output   analog   to   the   pressure indicator,  Two  sealed  adjustments  are  located  on  the side  of  the  transmitter  case.    One  is  placarded  ZERO ADJ and is used to adjust the zero volts output with no input  pressure.    The  second  adjustment  is  identified  as FSO   ADJ   so   that,   at   maximum   input   pressure,   the analog output of the unit will be 5v dc. 1-60