TM 55-4920-431-13
cleaning, preserving, adjusting, replacing, welding, riveting, and strengthening.
j. Overhaul. To restore an item to a completely serviceable condition as prescribed
by maintenance serviceability standards prepared and published for the specific item to be
overhauled.
k. Rebuild. To restore an item to a standard as nearly as possible to the original or
new condition in appearance, performance, and life expectancy. This is accomplished
through the maintenance technique of complete disassembly of the item, inspection of all
parts or components, repair or replacement of worn or unserviceable elements (items)
using original manufacturing tolerances and specifications, and subsequent reassembly of
the item.
A-4. Functional Groups. Standard functional groupings are not considered feasible for
aviation ground support equipment due to variation and complexity. Therefore
variations to functional groupings may occur.
A-5. Maintenance Categories and Work Times. The maintenance categories (levels)
AVUM, AVIM, and DEPOT are listed on the Maintenance Allocation Chart with individual
columns that indicate the work times for maintenance functions at each maintenance level.
Work time presentation such as 0.1 indicate the average time it requires a maintenance
level to perform a specified maintenance function. If a work time has not been established,
the columnar presentation shall indicate "--". Maintenance levels higher than the level of
maintenance indicated are authorized to perform the indicated function.
A-6. Tools and Test Equipment (Section III). Common tool sets (not individual tools),
special tools, test and support equipment required to perform maintenance functions are
listed alphabetically with a reference number to permit cross-referencing to column 5 in
the MAC. In addition, the maintenance category authorized to use the device is listed along
with the item National Stock Number (NSN) and, if applicable, the tool number to aid in
identifying the tool/device.
A-7. Remarks (Section IV). Remarks contained in column 6, with an alphabetical code,
are listed to provide a ready reference to the definition of the remarks.
A-4
