TM 5-2420-230-24-1
Maintenance Allocation Chart (MAC)
Introduction.
Section I.
B-1. THE ARMY MAINTENANCE SYSTEM MAC.
a. Section I, Introduction.. This introduction provides a general explanation of all maintenance and repair functions
authorized at the two maintenance levels under the Two-Level Maintenance System concept.
b. Section II, MAC for IHMEE.. This MAC (immediately following the introduction) designates overall authority and
responsibility for the performance of maintenance functions on the identified end item or component. The application
of the maintenance functions to the end item or component levels, which are shown on the MAC in column (4) as:
Field includes two columns, Unit maintenance and Direct Support maintenance. The Unit maintenance column is
divided again into two more subcolumns, C for Operator or Crew and O for Unit maintenance.
Sustainment includes two subcolumns, General Support (H) and Depot (D).
c. Section III, Tools and Test Equipment for IHMEE.. The tools and test equipment requirements (immediately
following the MAC) list the tools and test equipment (both special tools and common tool sets) required for each
maintenance function as referenced from the MAC.
d. Section IV, Remarks for IHMEE.. The remarks (immediately following the tools and test equipment requirements)
contain supplemental instructions and explanatory notes for a particular maintenance function.
B-2. MAINTENANCE FUNCTIONS.
Maintenance functions are limited to and defined as follows:
a. Inspect. To determine, through examination (e.g., by sight, sound, or feel), the serviceability of an item by comparing
its physical, mechanical, and/or electrical characteristics with established standards.
b. Test. To verify serviceability by measuring the mechanical, pneumatic, hydraulic, or electrical characteristics of an
item and comparing those characteristics with prescribed standards.
c. Service. Operations required periodically to keep an item of equipment in proper operating condition; e.g., to clean
(including decontamination, when required), to preserve, to drain, to paint, or to replenish fuel, lubricants, chemical
fluids, or gases.
d. Adjust. To maintain or regulate, within prescribed limits, by bringing into proper position, or by setting the operating
characteristics to 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 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.
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