TM 55-1680-317-23&P
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 near 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 life 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.
B-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
remark.
B-4
