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