equipment  (SE)  to  the  squadrons.  Squadron maintenance personnel are usually assigned to the squadron  maintenance  department.  However,  some personnel may be assigned temporarily to the station’s or ship’s AIMD. Maintenance  Types The term aircraft maintenance has a very general meaning. It could mean the maintenance performed in minutes at the squadron level to months of overhaul in an  industrial-type  facility.  More  than  the  words maintenance  or  aircraft  maintenance  are  needed  to indicate a specific meaning. There are two major types of   maintenance-rework   and   upkeep.   Categories tvithin the major types of maintenance are standard revvork  and  upkeep  and  special  rework  and  upkeep. The following paragraphs discuss these types and categories  of  maintenance. REWORK MAINTENANCE.—Rework   main- tenance is the restorative or additive work performed on aircraft, aircraft equipment, and aircraft SE. Naval aviation depots, contractor plants, and other industrial establishments do this type of maintenance. Standard rework and special rework come under the general heading of rework maintenance. Standard  Rework.—Standard rework is a com- prehensive depot-level inspection of selected aircraft structures and materials, correction of critical defects, incorporation  of  certain  technical  directives,  and limited removal and rework of scheduled removal components  (SRCs).  It  also  includes  equipment history record (EHR), assembly service record (ASR), and module service record (MSR) items. Standard rework  is  commonly  known  as  standard  depot-level maintenance  (SDLM). Special  Rework.—Special rework is work done to  aircraft,  aircraft  equipment,  and  aircraft  SE  to improve or change their capability to perform specific functions. This is done by replacing or repairing parts or equipment of the aircraft. Normally, special rework is depot-level work. UPKEEP  MAINTENANCE.—Upkeep    main- tenance is the preventive, restorative, or additive work performed on aircraft, equipment, and SE by operating units and aircraft SE activities. It includes servicing, periodic   inspection,   functional  and  bench  tests, replacement,  preservation,  modification,  and  repair. Upkeep is divided into two categories, standard and special. Military and contractor personnel perform upkeep.  The  aircraft  controlling  custodians  (ACCs) manage the process. Standard  Upkeep.—Standard  upkeep  main- tenance is the periodic or scheduled work performed on aircraft, equipment, and SE after (and as a result of) completion of a prescribed number of flying hours or calendar days. Such work is performed in compliance with  prescribed  inspection  or  replacement requirements,  and  is  also  known  as  scheduled maintenance. Special Upkeep.—Specialupkeep is the work done  to  aircraft,  equipment,  and  SE  to  improve, change, or restore their capability to perform specific mission  functions.  Special  upkeep  maintenance includes replacement, removal, addition, alteration, or repair of parts, equipment, or aircraft without regard to flying hours or operating times, and is also known as  unscheduled  maintenance. Q3.    What are the major types of aircraft maintenance? Q4.    The restorative or additive work performed on aircraft, equipment, or support equipment is what type of maintenance? Q5.   Standard rework is also known as what type of maintenance? Q6.    What  is  special  rework? Q7.    Upkeep maintenance is performed by what activities? Q8.   Standard upkeep is also known as what type of maintenance? Q9.   Maintenance performed on aircraft without regard to operating hours or calendar is known as what type of maintenance? Maintenance Levels All aircraft maintenance functions are divided into three  distinct  levels-organizational,  intermediate,  and depot. To determine the extent to which a repair task can be undertaken, the maintenance activity refers to the maintenance instruction manuals (MIMs), the operating and service instruction manuals, or the technical directives (TDs) that pertain to each weapon system or component. The levels of maintenance are discussed in the following paragraphs. Organizational-level   maintenance   is   work performed by an operating unit on a day-to-day basis in  support  of  its  own  operations.  Maintenance 1-2