f. Calibrate. To determine the corrections to be made in the readings of instruments or test equipment 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 instrument 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 unserviceable
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 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.
B-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.
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 indicate 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 indicated function.
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.