TM 5-2590-512-13&P i.    Repair.        The    application    of    maintenance services,    including    fault    location    /troubleshooting2, removal   /   installation,   and   disassembly   /   assembly3 procedures    and    maintenance    actions4    to    identify troubles    and    restore    serviceability    to    an    item    by correcting specific damage, fault, malfunction, or failure in    a    part,    subassembly,    module    (component    or assembly), end item, or system. j.    Overhaul. That maintenance effort (service/action)    prescribed    to    restore    an    item    to completely serviceable/ operational condition as required    by    maintenance    standards    in    appropriate technical    publications    (i.e.,    DMWR).        Overhaul    is normally the highest degree of maintenance performed by the Army. Overhaul  does  not  normally  return  an  item  to  like  new condition. k.    Rebuild.      Consists   of   those   services/actions necessary for the restoration of unserviceable equipment  to  a  like  new  condition  in  accordance  with original manufacturing standards.  Rebuild is the highest degree    of    material    maintenance    applied    to    Army equipment.    The  rebuild  operation  includes  the  act  of returning    to    zero    those    age    measurements    (e.g., hour/miles)    considered    in    classifying    Army    equip ment/components. B-3.  Explanation of Columns in the MAC, Section II. a.    Column  1,  Group  Number.    Column  1  lists functional  grouping  codes,  the  purpose  of  which  is  to identify maintenance significant components, assemblies,  subassemblies,  and  modules  with  the  next higher assembly. b.    Column 2, Component / Assembly.  Column 2 contains the item names of components, assemblies subassemblies,  and  modules  for  which  maintenance  is authorized. c.    Column 3, Maintenance Function.  Column 3 lists the functions to be performed on the item listed in Column 2.  (For detailed explanation of these functions, see Paragraph B-2.) d.    Column   4,   Maintenance   Level.      Column   4 specifies   each   level   of   maintenance   authorized   to perform each function listed in Column 3, by indicating work  time  required  (expressed  as  manhours  in  whole hours or decimals) in the appropriate subcolumn.  This work-time  figure  represents  the  active  time  required  to perform that maintenance function at the indicated level of  maintenance.    If  the  number  or  complexity  of  the tasks   within   the   listed   maintenance   function   vary   at different    maintenance    levels,    appropriate    work-time figures are shown for each level.  The work-time figure represents the average time required to restore an item (assembly, subassembly, component, module, end item, or system) to a serviceable condition under typical field operating  conditions.    This  time  includes  preparation time   (including   any   necessary   disassembly/assembly time),   troubleshooting/fault   location   time,   and   quality assurance   time   in   addition   to   the   time   required   to perform the specific tasks identified for the maintenance functions authorized in the maintenance allocation chart. The  symbol  designations  for  the  various  maintenance levels are as follows: C - Operator or crew maintenance O - Unit maintenance F - Direct support maintenance L - Specialized Repair Activity (SRA)s H - General support maintenance D - Depot maintenance ¹Services - Inspect, test, service, adjust, align, calibrate, and/or replace. ²Fault location/troubleshooting - The process of investigating and detecting the cause of equipment malfunctioning; the act of isolating a fault within a system or unit under test (UT). ³Disassembly/assembly - The step-by-step breakdown (taking apart) of a spare/functional group coded item to the level of its least component, that is assigned an SMR code for the level of maintenance under consideration (i.e., identified as maintenance significant). ⁴Actions - Welding, grinding, riveting, straightening, facing, machining, and/or resurfacing. ⁵This maintenance level is not included in Section II, column (4) of the Maintenance Allocation Chart.  Functions to this level  of  maintenance  are  identified  by  a  work-time  figure  in  the  "H"  column  of  Section  II,  column  (4),  and  an associated reference code is used in the Remarks column (6).  This code is keyed to Section IV, Remarks, and the SRA complete repair application is explained there. B-2