HOW  TO  USE  THIS  MANUAL  (TM  55-1520-240-T) This   manual   has   17   Chapters   that   have   instructions   for   troubleshooting   72   CH-47   Helicopter   Systems. apter   1   has: The   Complete   List   of   Troubleshooting   Symptoms   you   will   find   in   this   manual.   This   list   outlines   each chapter   by   system   and   symptom. Complete   wiring   for   300   Series   Connectors   and   Receptacles,   Terminal   Boards,   and   Ground   Devices. Chapters   2   thru   17   have   sets   of   troubleshooting   instructions   that   include: A   Chapter   outline   of   all   systems   and   symptoms   found   in   the   beginning   of   each   Chapter. Connector  part  numbers  and  pin  patterns   for  each  connector  and  receptacle  in  systems  contained in   chapter.   Also   included   are   relay  termination  views   and  ground   termination   types   and  location. System   Schematics   and/or  Wiring   Diagrams. Visual   Checks   with   locator   figures   and   step   by   step   procedures. Operational   Checks  with   locator   figures   and   step   by   step   procedures. Fault  Isolation  Procedures   with   locator   figures   and   troubleshooting   logic   for   specific   system   faults. HOW TO FIND WHAT YOU NEED Maintenance—Refer   to    TM    55-1520-240-23. Troubleshooting—Use   the   index   in   Chapter   1   or   in   the   beginning   of   each   chapter.   This   is   where   you   will   find the   system   troubleshooting   procedures   (visual   checks,   operational   checks   and   fault   isolation   procedures). The   troubleshooting   procedures   are   listed   under   the   name   of   the   system   that   the   component   or   system belongs   to. 2.   Each   system   has   a   number: Example: System System No. 9-15 Cabin   and   Ramp   Lights 3.   Each   item   in   your   set   of   troubleshooting   instructions   has   a   task   number.   The   system   number   is   prefixed   to each   of   the   item   task   numbers. Example: System System   Symptom No. 9-15 Cabin   and   Ramp   Lights Wiring   Diagram Visual   Check Operational    Check Cabin   and   Ramp   Circuit   Breaker Does   not   Stay   Closed Task   No. 9-15.1 9-15.2 9-15.3 9-15.4 TASK  PREPARATION Each    Troubleshooting    procedure    begins    with    INITIAL    SETUP    information.    Read tells   you   what   you   need   and   what   you   have   to   know   before   you   begin   the   job. it   carefully T M     5 5 - 1 5 2 0 - 2 4 0 - T before   starting.   It 1. 2. 3. 4. 5. 6. 7. 8. 9. Applicable   Configurations.   Tells   you   what   configurations   or   effectivity   the   task   applies   to. Tools.   If   any   tools   from   your   tool   kit   are   needed,   just   the   kit   is   listed.   Tools   needed   that   are   not   in   the   kit are   called   for   by   name.   Special   ground   support   tools,   containers,   and   test   equipment   are   listed   by   tool number   (Txx).   Find   these   items   in   TM   55-1520-240-23. Materials.   Materials   needed   are   listed   by   expendable   number   (EXX).   Find   these   items   in   TM   55-1520- 240-23. Parts.   New   parts   required,   such   as   gaskets,   packings,   and   washers,   are   listed   by   name   only.   If   parts   are not   needed,   you   will   not   see   this   heading. Personnel   Required.   Each   MOS   needed   to   do   the   task   is   Iisted.   When   more   than   one   of   any   MOS   is needed,   the   number   is   shown   in   parentheses. References.  Lists   references   such   as   TM   55-1520-240-23.   These   references   will   provide   where   infor- mation   can   be   found   when   you   need   to   repair   or   replace   a   part   or   component.   When   more   than   one reference   is   listed,   the   Fault   Isolation   Procedure   blocks   will   contain   a   refer   to   statement   for   all   references other   than   TM   55-1520-240-23. Equipment   Condition.   Procedures  which  must  be  done  before  starting  the  task  are  listed  and  task  or TM   number   is   given.   Tasks   that   are   not   indented   under   a   TM   manual   can   be   found   in   this   manual.   Refer to   the   TM   manual   listed   above   the   indented   tasks. General   Safety   Instructions.   These   are   safety   precautions   that   must   be   observed   throughout   task. Warnings   include   basic   first   aid   instructions. Locator   Figure.   The   area   of   the   helicopter   where   the   task   will   be   performed   is   shown,   with   components to   be   worked   on   called   out. TASK   PERFORMANCE 1. 2. 3. 4. 5. Visual   Checks   are   performed   to   determine   if   the   cause   of   the   system   fault   is   visually   apparent. Operational   Checks   are   performed   step   by   step   on   the   system   to   determine   the   system   fault.   Continue the   operational   check   TASK   until   the   symptom   is   confirmed   in   the   RESULT   column. Fault   Isolation   Procedures   are   performed   to   identify   the   specific   trouble   in   the   system.   Start   with   the   first block.   Read   it   through   and   answer   the   question.   The   questions   will   always   have   a   YES   or   NO   answer,   If you   answer   the   question   YES,   follow   the   direction   of   the   YES   arrow   to   the   next   block.   If  you  answer   the question   NO,   follow   the   direction   of   the   NO   arrow   to   the   next   block.   Continue   troubleshooting   until   the symptom   cause   is   identified. Use   the   integrated   schematic   during   troubleshooting   for   a   view   of   system   component   connections   and system   interfaces. Use   the   wiring   diagram   when   the   troubleshooting   instructions   require   wire   tests   to   isolate   the   symptom cause. Change  2 v