MAINTENANCE ALLOCATION CHART (MAC)

TM 10-3930-673-20-2

B-2. MAINTENANCE FUNCTIONS (CONT)

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 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.

g. 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 system.

h. Replace. To remove an unserviceable item and install a serviceable counterpart in its place. "Replace" is authorized

by the MAC and the assigned maintenance level is shown as the third position code of the SMR code.

i. Repair. The application of maintenance services1 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 a 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. hours/miles)

considered in classifying Army equipment/components.

B-3. EXPLANATION OF COLUMNS IN THE MAC, SECTION II

a. Column (1), Group Number. Column 1 lists functional group code numbers, 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 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 varies at different

maintenance levels, appropriate work time figures are to be shown for each level. The work time figure represents the average

1. Services - Inspect, test, service, adjust, align, calibrate, and/or replace.

2. Fault location/troubleshooting - The process of investigating and detecting the cause of equipment malfunction-

ing; the act of isolating a fault within a system or unit under test (UUT).

3. 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).

4. Actions - Welding, grinding, riveting, straightening, facing, machining, and/or resurfacing.

B-2