c. Service. Operations required periodically to keep an item in proper operating condition, i.e., to clean (includes
decontaminate), to preserve, to drain, or to replenish fuel, lubricants, hydraulic fluids, or compressed air supplies.
d. Adjust. To maintain within prescribed limits, by bringing into proper or exact position, or by setting the operating
characteristics to the specified parameters.
e. Align. To adjust specified variable elements of an item to bring about optimum or desired performance.
f. Calibrate. To determine and cause corrections to be made or to be adjusted on instruments or test measuring and
diagnostic equipment used in precision measurement. Consists of comparison 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
g. Install. The act of emplacing, seating, or fixing into position an item, part, or module (component or assembly) in
a manner to allow the proper functioning of an equipment or system.
h. Replace. The act of substituting a serviceable like type part, a subassembly, or module (component or assembly)
for an unserviceable counterpart.
i. Repair. The application of maintenance services (inspect, test, service, adjust, align, calibrate, or replace) or other
maintenance actions (welding, grinding, riveting, straightening, facing, remachining, or resurfacing) to 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) necessary to restore an item to a completely serviceable
operational condition as prescribed 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 a 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 materiel maintenance
applied to Army equipment. The rebuild operation includes the act of returning to zero those age measurements
(hours/miles, etc.) considered in classifying Army equipment/components.
B-4. EXPLANATION OF COLUMNS IN THE MAC, SECTION II
a. Column (1), Group Number. Column 1 lists functional group code numbers which are assigned to identify
maintenance significant components, assemblies, subassemblies, and modules to their next higher assembly.
b. Column (2), Component/Assembly. Column 2 contains the item names of components, assemblies, subassemblies,
and modules for which group numbers (column 1) are assigned and for which maintenance is authorized.
c. Column (3), Maintenance Function. Column 3 lists the functions to be performed on items listed in column 2.