TM   55-4920-414-13&P b.  Unscrew  malfunctioned  pressure  reducer  from Pilot Assist Hydraulic Module assembly (Figure 4-3 ). c. Coat new packings, seal and threads of replace- ment  pressure  reducer  with  hydraulic  fluid  (item  3, App D), before installing. d. Install new packings and new seal on replacement pressure reducer. e.  Screw  replacement  pressure  reducer  into  Pilot Assist  Hydraulic  Module  assembly.  Torque  to  238  - 262 inch-pounds. f.  Install  Iockwire  (item  7,  App  D)  between  pressure reducer  valve  and  thermal  relief  valve.  Refer  to  TM 55- 1500-204-25/ 1. 4-15.  SAS  Pressure  Switch  Replacement. To keep dirt from Pilot Assist Hydraulic Module assembly, and prevent fluid loss, make sure Pilot Assist Hydraulic Module assembly  is  clean  before  maintenance. Replace SAS Pressure switch only in a clean  place.  Have  replacement  switch ready  for  installation  before  malfunc- tioned switch is removed. It is not neces- sary  to  remove  Pilot  Assist  Hydraulic Module  assembly  from  Test  Fixture manifold. a.  Remove  Iockwire. b. Disconnect  electrical  connector  from  malfunc- tioned SAS pressure switch (Figure 4-4). c.  Have  container  of  at  least  1  quart  to  catch  hy- draulic  fluid. d. Remove pressure switch and packings from Pilot Assist  Hydraulic  Module  assembly. e.  Coat  new  packings  and  packing  seats  with  hy- draulic fluid (item 3, App D). f.  Install  new  packings  on  SAS  pressure  switch. Install  new  switch  in  Pilot  Assist  Hydraulic  Module assembly. Torque to 175 inch-pounds. g. Install lockwire (item 7, App D). Refer to TM 55- 1500-204-25/1. 4-16.  Thermal  Relief  Valve  Replacement To keep dirt from Pilot Assist Hydraulic Module  assembly,  make  sure  Pilot  Assist Hydraulic Module assembly is clean be- fore  maintenance.  Replace  relief  valve only in a clean place. Have replacement valve  ready  for  installation  before  mal- functioned  valve  is  removed.  It  is  not necessary  to  remove  Module  assembly from Test Fixture manifold. a. Remove lockwire between pressure reducer valve and thermal relief valve. b.  Unscrew  malfunctioned  pressure  reducer  from Pilot Assist Hydraulic Module assembly (Figure 4-5 ). c.  Coat  new  packing  of  replacement  valve  with hydraulic fluid (item 3, App D), before installing. d. Install new packing on replacement valve. e.  Screw  replacement  valve  into  Pilot  Assist  Hy- draulic Module assembly. Torque to 75 inch-pounds. f. Install lockwire (item 7, App D) between pressure reducer  valve  and  thermal  relief  valve.  Refer  to  TM 55-1500-204-25/1. 4-17.   Pilot Assist Hydraulic Module Assembly Replacement. To keep  Pilot  Assist  Hydraulic  Module assembly  free  of  dirt  during  repair,  make sure   all   ports   are   covered.   Remove Module assembly only in a clean place. a.   Disconnect   electrical   connector   from   shut-off valves (Figure 4-6 ). b. Disconnect electrical connector from SAS pressure switch. c. Unbolt and remove Pilot Assist Hydraulic Module assembly   from   Test   Fixture   manifold   by   pulling straight up on module. d. Clean top surfaces of female couplings with low- lint  cloth  (item  4,  App  D).  Flush  with  Clean  All  D (item 5, App D). e. Position Pilot Assist Hydraulic Module assembly on Test Fixture manifold making sure quick-disconnect couplings   on   Module   assembly   line   up   with   Test Fixture  manifold. 4-11