* Complete Rear: Maintenance capacity, capability, and authority to perform all corrective maintenance
tasks of the "Repair" function in a use/user environment in order to restore serviceability to a failed item.
(1) Source Code. The source code tells you how you get an item needed for maintenance,
repair, or overhaul of an end item/equipment. Explanations of source codes follow.
Stocked items; use the applicable NSN to request/requisition items with these
source codes. They are authorized to the category indicated by the code
entered in the 3rd position of the SMR code.
**NOTE : Items coded PC are subject to deterioration.
XA - - Do not requisition an "XA"-coded item. Order its next higher assembly. (Also, refer to the NOTE below.)
XB - - If an "XB" item is not available from salvage, order it using the CAGE Code and part number given.
XC - - Installation drawing, diagram, instruction sheet, field service drawing, that is identified by manufacturer's part
XD - - Item is not stocked. Order an "XD"-coded item through normal supply channels using the CAGE Code and part
number given, if no NSN is available.
Cannibalization or controlled exchange, when authorized, may be used as a source of supply
for items with the above source codes, except for those source coded "XA" or those aircraft
support items restricted by requirements of AR 700-42.
Maintenance Code. Maintenance codes tells you the level(s) of maintenance authorized to USE and
REPAIR support items. The maintenance codes are entered in the third and fourth positions of the SMR Code as
The maintenance code entered in the third position tells you the lowest maintenance level authorized
to remove, replace, and use an item. The maintenance code entered in te third position will indicate authorization to one
of the following levels of maintenance.
-Crew or operator maintenance done within
aviation unit maintenance.
-Aviation unit category can remove, replace, and use
The maintenance Code entered in the fourth position tells whether or not the item is to be repaired
and identifies the lowest maintenance level with the capability to do complete repair (i.e., perform all authorized repair
functions.) (NOTE: Some limited repair may be done on the item at a lower level of maintenance, if authorized by the
Maintenance Allocation Chart (MAC) and SMR codes.) This position will contain one of the following maintenance codes.