TM 55-4920-328-13 graduated from 0 to 1,000 psig in 25-psi increments. (b) During a starting cycle, the engine in the hydraulic start system is cranked by the 12volt starter on the gasoline engine.  The relief valve selector switch 13, figure 1-8) is placed in the up position to start a T55 gas turbine  engine,  and  in  the  down  position  to  start  a  T73 engine.      The   START/RUN   switch   (4,   figure   1-26)   is placed   in   the   START   position   to   crank   the   gasoline engine.      Prior   to   the   start   mode,   the   normally-open, solenoid-operated  valve  (10,  figure  1-8)  in  the  supply line bypasses fluid to return.  After the gasoline engine is started, the switch is positioned to RUN.  At this time, the   maximum   starter   speed   is   selected   just   prior   to making  the  engine  start.    Then  the  START  switch  (33, figure  1-24)  is  energized.    This  action  applies  28v  do power to the solenoid-operated valve to close the valve and  break  the  bypass  portion  of  the  hydraulic  circuit. This  action,  in  turn,  applies  the  full  output  of  the  pump assembly   to   the   hydraulic   starter   on   the   gas   turbine engine to crank the engine.  After engine lightoff and at the  speeds  specified  in  chapter  3  of  this  manual,  the starter     speed     is     reduced     to     minimum,     then     the START/RUN  switch  is  positioned  to  OFF.    This  action will reduce the speed and shut down the gasoline engine in    the    hydraulic    start    system    and    stop    the    pump assembly. (6) Test trailer fuel system. (a) The test trailer fuel system (figure 1-10) provides MIL-T-5624, JP-4 or JP-5 fuel, as required, to an  engine  under  test.    The  fuel  system  is  operated  by 208v  ac,  single-phase,  60  Hz  electrical  power  supplied from   the   METS   generator   set.      The   fuel   system   is installed   on   and   below   the   aft   end   of   the   test   trailer deck.  The system (shown schematically in figure 1-11) consists essentially of an aluminum fuel tank assembly (1,   figure   1-10)   and   a   fuel   pump   (13)   connected   to plumbing    lines    and    auxiliary    components.        Quick- disconnects   (9)   are   provided   for   interconnection   with engine supply and return hose assemblies.  A fluid level transmitter (14) is installed in the fuel tank assembly to provide electrical signals to indicate fuel quantity status to the test technician.  A flow straightener (6), flowmeter (5), and thermocouple (4) are installed in a fuel manifold downstream from the fuel tank assembly.  A 10-micron filter (8) in the line filters foreign solids from the fuel.  A shutoff    solenoid    valve    (10)    is    installed    in    the    line downstream from the thermocouple.  The fuel pump unit consists of a three-phase, hermetically sealed ac motor driving  a  dual-impeller  pump.    Both  are  designed  for submerged  operation  in  the  fuel  tank  assembly.    The motor    is    provided    with    thermal    protection    against excessive   heat   and   overload   conditions.      A   second shutoff  solenoid  valve  (7)  is  installed  in  the  return  line for use in the OSG fuel bleed subsystem.  This valve is operated  only  during  test  of  certain  engines  outlined  in chapter  2  of  this  manual.    Refer  to  the  interconnection information contained in that chapter. (b) When electrical power is made available,   the   fuel   system   is   energized   through   the FUEL PUMP circuit breaker CB2 (4, figure 2-9) and the FUEL PUMP START switch S19 (16, figure 1-26).  The operator's sub-module is then energized to allow fuel to flow through the inlet line to the engine.  The fuel pump provides  a  nominal  output  pressure  of  26  psig  at  10.2 gpm    flow    through    the    10-micron    filter.        The    flow straightener (6, figure 1-10) installed on the inlet side of the   turbine-type   flowmeter   (5)   tends   to   remove   the swirling  action  from  the  flow  of  fuel.    The  flow  meter provides   pulsating   electrical   signals   to   the   fuel   flow monitor unit (16, figure 1-23) in the analyzer sub-module when consumption of fuel is monitored during a test.  In the event of an emergency shutdown of the system, the ENGINE   FUEL   SOLENOID   switchlight   unit   S10   (30, figure  1-24)  is  deenergized.    This  action  immediately shuts  off  the  supply  of  fuel  to  the  engine.    For  certain engines  listed  in  chapter  2,  the  OSG  BLEED  OPEN/ OSG BLEED CLOSED switchlight unit S3 (26, figure 1- 24) is deenergized during a test while fuel consumption is   monitored.      Refer   to   chapter   3   of   this   manual   for complete   operating   instructions   for   the   fuel   system. 1-13