MAINTENANCE FUNCTIONS - Continued
Calibrate. To determine and cause corrections to be made or to be adjusted on instruments of test,
measuring, and diagnostic equipment used in precision measurement. Consists of comparisons of two
instruments, one of which is a certified standard of known accuracy, to detect and adjust any discrepancy
in the accuracy of the instrument being compared.
Remove/Install. To remove and install the same item when required to perform service or other
maintenance functions. Install may be the act of emplacing, seating, or fixing into position a spare, repair
part, or module (component or assembly) in a manner to allow the proper functioning of an equipment or
Replace. To remove an unserviceable item and install a serviceable counterpart in its place. "Replace" is
authorized by the MAC and assigned maintenance level is shown as the third position code of the Source,
Maintenance and Recoverability (SMR) code.
The following definitions are applicable to the "repair" maintenance function:
Services. Inspect, test, service, adjust, align, calibrate, and/or replace.
Fault 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 (UUT).
Disassembly/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).
Actions. Welding, grinding, riveting, straightening, facing, machining, and/or
Repair. The application of maintenance services, including fault location/troubleshooting,
removal/installation, disassembly/assembly procedures, and maintenance actions 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.
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.
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
EXPLANATION OF COLUMNS IN THE MAC
Column 1, Group Number. Column 1 lists 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 item 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.)