0063 00  TM 10-1670-287-23&P 11. Overhaul. That maintenance effort (service/action) prescribed to restore an item to a completely  serviceable/operational condition as required by maintenance standards in appropriate technical  publications. Overhaul is normally the highest degree of maintenance performed by the Army.  Overhaul does not normally return an item to like new condition.  12. 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., hours/miles.) considered in classifying Army  equipment/components.  C  Operator or Crew maintenance  O Unit maintenance F  Direct Support maintenance  L  Specialized Repair Activity  H  General Support maintenance  D Depot maintenance Field: Sustainment: Explanation of Columns in the MAC  Column (1) Group Number. Column (1) lists Functional Group Code (FGC) numbers, the purpose of  which is to identify maintenance significant components, assemblies, subassemblies, and modules with  the Next Higher Assembly (NHA).  Column (2) Component/Assembly. Column (2) contains the names of components, assemblies,  subassemblies, and modules for which maintenance is authorized.  Column (3) Maintenance Function. Column (3) lists the functions to be performed on the item listed in  column (2). (For a detailed explanation of these functions refer to “Maintenance Functions” outlined  above).  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 varies at different maintenance levels,  appropriate work time figures are to be 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 MAC. The system designations for the various maintenance  levels are as follows:  Change 2 0063 00-3