TM 55-4920-431-13
MAINTENANCE ALLOCATION CHART
Section I. INTRODUCTION
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 aircraft. These maintenance levels: Aviation Unit Maintenance
(AVUM), Aviation Intermediate Maintenance (AVIM) and Depot Maintenance are depicted on the MAC as:
AVUM which corresponds to the O code in the Repair Parts and Special Tools List (RPSTL).
AVIM which corresponds to the F code in the Repair Parts and Special Tools List (RPSTL).
DEPOT which corresponds to the 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). AVUM activities will be staffed and equipped to perform high
frequency "On-Equipment" maintenance tasks required to retain or return equipment to a serviceable
condition. The maintenance capability of the AVUM will be governed by the MAC and limited by the
amount and complexity of support equipment, facilities required, and number of spaces 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. (Assignment 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 equipment operational readiness. Perform maintenance inspections and servicing to include
daily, intermediate, periodic 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 instruments, or
easy to use Test Measurement and Diagnostic Equipment (TMDE). Replace worn or damaged
modules/components which do not require complex adjustments or system alignments and which
can be removed/installed with available skills, tools and equipment. Perform operational and
continuity checks and make minor repairs. Perform servicing, functional adjustments, and minor
repair/replacement. 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 the aircraft crew chief or assigned aircraft repairman
will normally be limited to preventive maintenance, inspections, servicing, spot painting, stop
drilling, minor adjustments module/component fault diagnosis and replacement of selected
modules/components. Repair functions will normally be accomplished by the supporting
AVIM unit.
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