TM 55-4920-328-13 KEY TO FIGURE 1-27. 1. Blower 9A1 2. Filler Panel 3. Ancillary Panel Assembly 9A3 4. Engine Fuel Level Indicator Gage 5. 24-Hour Clock 6. Pressure Regulator 7. Coupling 8. Air Pressure Gage 9. Air Supply Switch 10. Pneumatic Control Assembly 9A2 11. Barometer 12. Right Hand Castle Assembly available  through  the  switch  to  energize  the  coil  of  the solenoid  to  open  the  valve.    The  valve  is  closed  by positioning the switch to OFF. c. Pressure  regulator.    The  pressure  regulator  (6, figure 1-27) installed in the pneumatic control assembly 9A2   (10)   is   a   pneumatic   unit   used   in   the   METS   air system  to  control  inlet  air  pressures  to  a  remote  water brake   assembly.      The   regulator   consists   of   a   spring case,   tee   handle,   adjustment   screw,   primary   spring, diaphragm,  stem  and  disc  holder  assembly,  secondary spring,  and  a  bottom  plug.    Turning  the  control  knob clockwise increases outlet air pressure.  Air at 150 psig pressure  enters  the  inlet  port  of  the  regulator  and  the pressure is reduced to an outlet pressure of approximately  25  psig.    Refer  to  the  applicable  engine overhaul  technical  manual  for  exact  outlet  pressures. Output  of  the  regulator  is  delivered  to  a  water  brake assembly to aid operation.  The water brake assembly is used  as  a  power  absorption  device,  simulating  actual loads imposed on the engine during use.  The pressure regulator is self-relieving; therefore, system air bleed is not  required  during  adjustment  of  the  unit  to  deliver  a different outlet pressure. 2.    Ancilliary    panel    assembly    9A3.        The ancillary  panel  assembly  (3,  figure  1-27)  consists  of  a rectangular    panel    mounting    a    barometer    (11),    and ENGINE FUEL LEVEL indicator gage (4), and a 24-hour clock  (5).    The  panel  is  19.00  inches  wide  and  8.72 inches  high.    The  panel  is  provided  with  left  and  right handles    and    is    secured    to    the    right    hand    castle assembly   enclosure   with   four   sets   of   flush-mounted screws and washers. a. Barometer.  The barometer (11, figure 1-27) is a circular   scale   aneroid   instrument   having   a   full   scale range  of  28  to  31  inches  hg,  through  one  revolution  of the  pointer.    The  six-inch  diameter  scale  has  a  total length    of    17    inches    with    graduations    in    0.01-inch increments,  and  a      TM  55-4920-328-13      full  scale range   accuracy   of   0.3   percent.      The   unit   is   panel- mounted  with  three  sets  of  screws,  washers,  and  nuts. The barometer movement is operated by the expansion and  contraction  of  a  bellows  type  capsule.    Expansion and  contraction  of  the  capsule  is  caused  by  barometric pressure  fluctuations.    The  mechanism  attached  to  the capsule causes the pointer to rotate by movement of a pinion and sector gear. b. Engine  fuel  level  indicator  gage.    The  engine FUEL  LEVEL  indicator  gage  (4,  figure  1-27)  is  a  liquid level  instrument  that  provides  display  of  fuel  level  in  a remote  tank.    The  indicator  is  electrically  excited  by  a transmitter which is immersed in the tank, using 28v dc electrical power for subsystem operation.  The indicator dial  divisions  range  from  E  (empty)  to  F  (full)  in  1/8th graduations.        The    position    of    a    float    in    the    fuel transmitter   causes   a   resistive   change   in   transmitter output  to  the  indicator,  varying  from  0  to  28v  dc.    This output  voltage  is  sensed  by  the  indicator.    Rotation  of the   needle   provides   liquid   level   quantity   indication, depending on the magnitude of the voltage input to the indicator. c. 24-Hour  clock.    The  24-hour  clock  (5,  figure  1- 27) is a spring-operated unit used to display actual times which   are   record   during   a   test.      No   maintenance   is required for the unit. (12)  Engine  test  dolly  assembly.    The  engine  test  dolly assembly  (figure  1-28)  includes  a  frame  assembly  (1), running  gear  assembly  (2),  mount  stand  assembly  (3), engine    mount    ring    assembly    (4),    data    acquisition assembly (5), and four tiedown rings.(6). (a)    Dolly.  The dolly permits engines to be dressed in a convenient area, towed to the test site, and lifted to the engine test trailer bed for testing.  The aluminum    structure,    with    mount    ring,    can    support engines   and   water   brake   assemblies   weighing   up   to 2,000  pounds.    The  aft  running  gear  has  two  15-inch wheels with pneumatic tires.  The forward running gear has  a  steerable  front  axle  assembly  with  a  removable drawbar   (7)   and   two   15-inch   wheels   with   pneumatic tires.    The  aft  parking  brake  is  manually  controlled  by operating a lever on the left side of the engine test dolly. The   dolly   axles   are   secured   to   four   latch   arm   guide assemblies (17 through 21, figure 1-3) on the test trailer deck for support and stability during testing.  The ring on the engine mount ring assembly (4, figure 1-28) is used for   lifting   the   dolly   to   the   test   trailer   bed,   with   most engines installed. A special sling is provided in the T73 engine accessories for lifting the dolly with this engine installed. 1-55