The maintenance allocation chart (MAC), explained

A maintenance allocation chart (MAC) is the table in an Army technical manual (TM) that assigns each maintenance task on an item to a maintenance level and gives the labor hours for it. The introduction that MIL-STD-40051-2C, the Department of Defense standard for page-based TMs dated December 15, 2015, requires word for word in a MAC says the chart designates overall authority and responsibility for the performance of all maintenance tasks on the end item or component. AR 750-1, the Army maintenance policy dated April 29, 2026, requires maintenance tasks to be performed in accordance with the TM and the MAC.

Where the MAC sits in a technical manual

MIL-STD-40051-2C is approved for public release and supersedes Revision 2B of October 17, 2012. The original MIL-STD-40051, Technical Manual Preparation, is dated July 31, 1996, and was superseded by two parts, MIL-STD-40051-1 and MIL-STD-40051-2; the second covers page-based TMs. EverySpec, a third-party library, lists 2C as the newest page-based version it holds.

Appendix G of the standard covers supporting information. It requires these work packages to sit in a single chapter called "Supporting Information," in a set order: references, the MAC introduction, the MAC itself, components of end item and basic issue items, additional authorization list, expendable and durable items, tool identification, mandatory replacement parts, and the list the standard calls "critical safety items." The standard labels the MAC requirement "Maintainer/AMC only," so it applies to TMs that include the maintainer class or, for aircraft, the aviation maintenance company class. The introduction text "shall be prepared and included verbatim." There are two versions of that text, one for non-aviation equipment and one for aviation.

The chart has six columns: group number, component or assembly, maintenance function, maintenance level, tools and equipment reference code, and remarks code. A tools and test equipment table and a remarks table follow it.

The maintenance functions

The introduction defines each function a MAC may list, and unused ones may be removed. The first thirteen in the non-aviation list are:

• Inspect. Compare an item's physical, mechanical, or electrical characteristics with established standards by examination, such as sight, sound, or feel.
• Test. Verify serviceability by measuring characteristics against prescribed standards, such as load testing of lift devices.
• Service. Periodic work that keeps an item in proper operating condition, such as replenishing fuel or lubricants.
• Adjust and align. Bring an item within prescribed limits, or adjust variable elements for optimum performance.
• Calibrate. Compare test equipment against a certified standard of known accuracy and correct any discrepancy.
• Remove and install. Take a component off to allow other maintenance, or place it to make it part of a higher level end item.
• Replace. Take off an unserviceable component and put a serviceable one in its place.
• Repair. Restore an item to completely serviceable or fully mission capable status, including welding, grinding, riveting, and machining.
• Paint. Prepare and apply coats of paint.
• Overhaul. Restore an item to completely serviceable condition under maintenance standards. The standard says "Overhaul does not normally return an item to a like new condition."
• Rebuild. Restore unserviceable equipment to like-new condition under original manufacturing standards, returning age measurements such as hours or miles to zero.

The list runs to 44 functions, ending with software tasks such as configure and debug.

The level codes

Column 4 holds the level. Each level has two sub-columns, and a man-hour figure in a sub-column authorizes that level to do the task. The man-hour figure is the task time multiplied by the number of maintainers; crew time is clock time only.

Code	Non-aviation MAC	Aviation MAC
C	Crew (field)	Not listed
O	Used by other Services in place of C	Aviation maintenance company (field)
F	Maintainer (field)	Aviation support battalion (field)
H	Below depot (sustainment)	Not listed
L	Specialized repair activity, shown in the H column with a remarks code	Theater aviation sustainment maintenance group and other organizations with National Maintenance Program certification (sustainment)
D	Depot (sustainment)	Depot (sustainment)

For joint service manuals, an asterisk next to C explains that other Services may use O. For ammunition, an X may replace the man-hour figure.

How the MAC ties to SMR codes and policy

Each repair part carries a source, maintenance, and recoverability (SMR) code. The MAC introduction states that the third position shows the level authorized to replace an item and the fourth the level authorized for complete repair. A D or K in either position means depot.

AR 750-1 sets the policy around the chart. Field maintenance organizations may perform all tasks "coded C, and F" in the MAC when skilled maintainers, tools, and test equipment are available. Corrective actions the MAC does not authorize at field level go to sustainment with turn-in documentation. The commanding general of the Army Materiel Command may grant field units authority for sustainment-level MAC tasks. DA Pam 750-1, the companion procedures pamphlet dated April 29, 2026, ties operator and crew replacements and adjustments to column C of the MAC, and directs maintenance activities to ensure the MAC is developed using reliability-centered maintenance. For aircraft, ATP 3-04.7, dated October 20, 2020, ties a maintenance company's field authority to the SMR code and the MAC.

What to check

• Which revision of MIL-STD-40051 does the TM follow, and does its MAC introduction match that revision's verbatim text?
• Is the chart an aviation MAC (O, F, L, D) or a non-aviation MAC (C, F, H, D)?
• Does the man-hour figure sit in the sub-column for the level actually doing the work?
• Do the third and fourth positions of the SMR code agree with the MAC for the same item?
• Is the job an overhaul or a rebuild, and does the paperwork reset age measurements only for a rebuild?
• If a field unit performs an H, L, or D task, where is the Army Materiel Command authority?

Azcuna's TRACE is one offline viewer for S1000D, MIL-STD-3001 XML, and PDF technical manuals. It keeps the source location and the markings of everything it shows and never modifies the source. It was proposed to NAVAIR under Navy SBIR Phase I topic DON26BZ05-NV078, and the proposal was submitted on September 23, 2026.

Sources

1. 1MIL-STD-40051-2C, Preparation of Digital Technical Information for Page-Based Technical Manuals (TMs) · Department of Defense, December 15, 2015, via EverySpec
2. 2MIL-STD-40051, Technical Manual Preparation · Department of Defense, July 31, 1996, via EverySpec
3. 3AR 750-1, Army Materiel Maintenance Policy · Headquarters, Department of the Army, April 29, 2026
4. 4DA Pam 750-1, Army Materiel Maintenance Procedures · Headquarters, Department of the Army, April 29, 2026 (administrative revisions July 8 and October 19, 2026)
5. 5ATP 3-04.7, Army Aviation Maintenance · Headquarters, Department of the Army, October 20, 2020

Where this shows up in our work

• TRACE, the offline S1000D and IETM viewer opens S1000D, MIL-STD-3001 and PDF technical manuals on a tablet with every marking intact.
• ELLMENT, the offline LLM for E-2D crews answers a crew's question from the aircraft's own manuals and cites the page, with no network.