TM 55-4920-431-13
MAINTENANCE ALLOCATION CHART
Section I. INTRODUCTION
A-1. Maintenance Allocation Chart.
a. This Maintenance Allocation Chart (MAC) assigns maintenance functions in accor-
dance 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 re-
quirements 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 pri-
marily of preventive maintenance and maintenance repair and replacement functions asso-
ciated with sustaining a high level of equipment operational readiness. Perform mainte-
nance 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 instruc-
tions. 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
