d. Adjust. To rectify to the extend necessary to bring into proper operating range.
e. Align. To adjust specified variable elements of an item to bring to optimum performance.
f. Calibrate. To determine the corrections to be made in the readings of instruments or test equip-
ment used in precise measurement. Consists of the comparison of two instruments, one of which is a
certified standard of known accuracy, to detect and adjust any discrepancy in the accuracy of the instru-
ment or test equipment being compared with the certified standard.
g. Install. To set up for use in an operational environment such as an emplacement, site or vehicle.
h. Replace. To replace unserviceable items with serviceable assemblies, subassemblies or parts.
i. Repair. To restore an item to serviceable condition through correction of a specific failure or un-
serviceable condition. This includes, but is not limited to, inspection, 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 tech-
nique 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.
B-4. Functional Groups. Group numbers correspond to the breakdowns in Repair Parts and Special
Tools List (RPSTL) TM 55-4920-429-23P.
B-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 indi-
cate the work times for maintenance functions at each maintenance level. Work time presentations 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 indi-
B-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.
Change 1 B - 3