TM 55-1520-240-23-11
SECTION I
B-1. MAINTENANCE ALLOCATION CHART.
a.
This Maintenance Allocation Chart (MAC) assigns maintenance functions in accordance with the Three
Levels of Maintenance concept for Army aviation. These maintenance levels (categories) — Aviation Unit
Maintenance (AVUM), Aviation Intermediate Maintenance (AVIM), and Depot Maintenance — are depicted
on the MAC as:
NO BREAK - WORK HARDER
AVUM, which corresponds to an O Code in the Repair Parts and Special Tools List (RPSTL)
NO BREAK - WORK HARDER
AVIM, which corresponds to an F Code in the Repair Parts and Special Tools List (RPSTL)
NO BREAK - WORK HARDER
DEPOT, which corresponds to a D Code in the Repair Parts and Special Tools List (RPSTL)
b.
The maintenance to be performed below depot and in the field is described as follows:
(1)
Aviation Unit Maintenance (AVUM). Activities will be staffed and equipped to perform high frequency
on-aircraft maintenance tasks required to retain or return aircraft systems to a serviceable condition.
The maintenance capability of AVUM will be governed by the Maintenance Allocation Chart (MAC)
and limited by the amount and complexity of ground support equipment (GSE), facilities required,
authorized manning strength, and critical skills available. The range and quantity of authorized spare
modules/components will be consistent with the mobility requirements dictated by the air mobility concept.
(Assignments of maintenance tasks to divisional company size aviation units will consider the overall
maintenance capability of the division, the requirement to conserve personnel and equipment resources,
and air mobility requirements.)
(a)
Company Size Aviation Units. Perform those tasks which consist primarily of preventive maintenance
and maintenance repair and replacement functions associated with sustaining a high level of aircraft
operational readiness. Perform maintenance inspections and servicing to include preflight, daily,
intermediate, periodic (or phased), and special inspections as authorized by the MAC or higher
headquarters. Identify the cause of equipment/system malfunctions using applicable technical manual
troubleshooting instructions, built-in-test equipment (BITE), installed aircraft instruments, or test,
measurement, and diagnostic equipment (TMDE). Replace worn or damaged modules components
that do not require complex adjustments or system alignment and which can be removed/installed
with available skills, tools, and ground support equipment. Perform operational and continuity checks
and make minor repairs to the electrical system. Inspect, service and make operational, check
capacity and pressure of hydraulic systems. Perform servicing, functional adjustments, and minor
repair/replacement to the flight control, propulsion, power train, and fuel systems. Accomplish airframe
repair that does not require extensive disassembly, jigging, or alignment. The manufacture of airframe
parts will be limited to those items which can be fabricated with tools and equipment found in current
air mobile tool and ship sets. Evacuate unserviceable modules/components and end items beyond the
repair capability of AVUM to the supporting AVIM.
(b)
Less than Company Size Aviation Units. Aviation elements organic to brigade, group, battalion
headquarters, and detachment size units are normally small and have less than ten aircraft assigned.
Maintenance tasks performed by these units will be those which can be accomplished by the aircraft
crew chief or assigned aircraft repairman and will normally be limited to preventive maintenance,
inspections, servicing, spot painting, stop drilling, application of nonstress patches, minor adjustments,
module/component fault diagnosis, and replacement of selected modules/components. Repair
functions will normally be accomplished by the supporting AVIM unit.
B-2
