TM 5-4320-215-12 APPENDIX II MAINTENANCE ALLOCATION 1.  General This  appendix  contains  a  maintenance  allocation chart    listing    all    maintenance    and    repair    operations authorized for the various echelons. 2.  Maintenance Maintenance is any action taken to keep materiel in a serviceable condition or to restore it to serviceability when   it   is   unserviceable.      Maintenance   of   materiel includes the following: a.      Service.      To   clean,   to   preserve,   and   to replenish fuel and lubricants. b.    Adjust.    To  regulate  periodically  to  prevent malfunction. c.  Inspect.  To verify serviceability and to detect incipient mechanical failure by scrutiny. d.    Test.    To  verify  serviceability  and  to  detect incipient mechanical failure by use of special equipment such as gages, meters, and so on. e. Replace. To substitute serviceable assemblies, subassemblies, and parts for unserviceable components. f.    Repair.      To   restore   an   item   to   serviceable condition   through   correction   of   a   specific   failure   or unserviceable  condition.    This  function  includes  but  is not limited to, inspecting, cleaning, preserving, adjusting, replacing, welding, riveting, and straightening. g.    Overhaul.    To  restore  an  item  to  completely serviceable   condition   as   prescribed   by   serviceability standards    developed    and    published    by    heads    of technical    services.        This    is    accomplished    through employment of the technique of "inspect and repair only as    necessary"    (IROAN).        Maximum    utilization    of diagnostic     and     test     equipment     is     combined     with minimum  disassembly  of  the  item  during  the  overhaul process. 3.  Explanation of Columns a.    Functional  Group.    The  functional  group  is  a numerical   group   set   up   on   a   functional   basis.      The applicable  functional  grouping  indexes  are  taken  from the  Corps  of  Engineers  Functional  Grouping  Indexes, and appear on the Maintenance Allocation Chart in their correct    numerical    sequence.        These    indexes    are normally  set  up  according  to  their  proximity  to  each other and their function. b.      Components   and   Related   Operation.      This column contains the functional index grouping heading, subgroup  headings,  and  a  brief  description  of  the  part starting  with  the  noun  name.    It  also  designates  the operation   to   be   performed   such   as   service,   adjust, inspect, test, replace, repair, and overhaul. c.  Echelon Maintenance. (1). First echelon. First echelon maintenance is that maintenance performed  by  the  user  or  operator  of the    equipment,    such    as    servicing, cleaning, lubricating, and limited adjustments.    It  also  includes  removal and replacement of items to accomplish servicing and lubricating. (2).      Second   Echelon.      Second   echelon maintenance is that maintenance. Performed by trained personnel provided  for  that  purpose  in  the  using organization,  such  as  replacement  of all   items   in   column   2,   limited   parts fabrication from bulk material, adjustments, and repair on assemblies, components,  and  end  items  that  can be    accomplished    without    extensive disassembly. (3). Third echelon. Third echelon maintenance is that maintenance performed by specially trained units in direct support of the using organization, 57