TM 10-5411-232-13&P CARGO BED COVER (CBC) M105A2 TRAILER, TYPE II 0021 00 MAINTENANCE ALLOCATION CHART (MAC) Maintenance Functions - Continued 6.    Calibrate.  To determine and cause corrections to be made or to be adjusted on instruments of test, measuring, and diagnostic equipment used in precision measurement.  Consists of comparisons 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 being compared. 7.    Remove/Install.  To remove and install the same item when required to perform service or other maintenance functions.  Install may be the act of emplacing, seating, or fixing into position a spare, repair part, or module (component or assembly) in a manner to allow the proper functioning of an equipment or system. 8.    Replace.  To remove an unserviceable item and install a serviceable counterpart in its place.  “Replace” is authorized by the MAC and assigned maintenance level is shown as the third position code of the Source, Maintenance and Recoverability (SMR) code. 9.    Repair.  The application of maintenance services, including fault location/troubleshooting, removal/installation, disassembly/assembly procedures, and maintenance actions to identify troubles and restore serviceability to an item by correcting specific damage, fault, malfunction, or failure in a part, subassembly, module (component or assembly), end item, or system. NOTE The following definitions are applicable to the ‘repair’ maintenance function: Services - Inspect, test, service, adjust, align, calibrate, and/or replace. Fault location/troubleshooting - The process of investigating and detecting the cause of equipment malfunctioning; the act of isolating a fault within a system or Unit Under Test (UUT). Disassembly/assembly - The step-by-step breakdown (taking apart) of a   spare/functional group coded item to the level of its least component, that is assigned an SMR code for the level of maintenance under consideration (i.e. identified as maintenance significant). Actions - Welding, grinding, riveting, straightening, facing, machining, and/or   resurfacing. 10. Overhaul.  That maintenance effort (service/action) prescribed to restore an item to a completely serviceable/operational condition as required by maintenance standards in appropriate technical publications.  Overhaul is normally the highest degree of maintenance performed by the Army.  Overhaul does not normally return an item to like new condition. 11. Rebuild.  Consists of those services/actions necessary for the restoration of unserviceable equipment to a like new condition in accordance with original manufacturing standards.  Rebuild is the highest degree of material maintenance applied to Army equipment.  The rebuild operation includes the act of returning to zero those age measurements (e.g., hours/miles, etc.) considered in classifying Army equipment/components. 0021 00-2