TM 55-1680-320-23 & P
MAINTENANCE ALLOCATION CHART
Section I. INTRODUCTION
B-1. Maintenance Allocation Chart.
a. The Maintenance Allocation Chart (MAC) assigns maintenance functions in accordance with the Three Levels of
Maintenance concept for Amy aviation.
These maintenance levels (categories) - Aviation Unit Maintenance (AVUM),
Aviation Intermediate Maintenance (AVIM) and Depot Maintenace - are depicted on the MAC as:
AVUM, which corresponds to an O Code in the Repair Parts and Special Took List (RPSTL)
AVIM, which corresponds to art F Code in the Repair Parts and Special Tools List (RPSTL)
DEPOT, which corresponds to an D Cede 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-Aircmft
maintenance tasks required to main or return aircraft systems to a serviceable condition.The maintenance capability of
the 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
sir mobility concept. (Assignments of maintenance tasks to divisional company size aviation units will consider the overall
maintenancecapability of the division, the requirement to conserve personal and equipment resources and air mobility
(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, intermdiate, periodic (or phased) and special
inspections as authorized by the MAC or higher headquarters. Identify the case 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 remove / installed with available skills, took and ground
support equipment. Perform operational and continuity checks and make minor repairs to the electrical system. Inspect,
service and make operational, capacity and pressure checks to hydraulic systems. Perform servicing functional adjustments
and minor repair / replacement to the flight control, propulsion, power train and fuel systems. Accomplish air frame repair
that does not require extensive disassembly, jigging or alignment. The manufacture of air frame parts will be limited to
those items which can be fabricated with tools and equipment found in current air mobile tool and shop 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 leas than ten aircraft assigned. Maintenance tasks performed by
these units will be those which can be accomplished by the aircraft crew chief or assigned airmail 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.
(2) Aviation Intermediate Maintenance (AVIM) provides mobile, responsive One-Stop maintenance support.
(Maintenance functions which are not conducive to sustaining air mobility will be assigned to depot maintenance), AVIM