Maintenance Functions - TM-9-4120-423-14-P0448

TM9-4120-423-14&P

Service. Operations required periodically to keep an item in proper operating condition, e.g., to

clean (includes decontaminate, when required), to preserve, to drain, to paint, or to replenish

fuel, lubricants, chemical fluids, or gases. This includes scheduled exercising and purging of

recoil mechanisms.

Adjust. To maintain or regulate, within prescribed limits, by bringing into proper position, or by

setting the operating characteristics to specified parameters.

Align. To adjust specified variable elements of an item to bring about optimum or desired

performance.

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.

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.

Replace. To remove an unserviceable item and install a serviceable counterpart in its place. The

MAC authorizes "Replace" and assigned maintenance level is shown as the third position code

of the Source, Maintenance and Recoverability (SMR) code.

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 (ET).

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.

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