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Maintenance Levels


DoD recognizes two levels of maintenance: Field level and Depot level maintenance. Field-level is comprised of both organizational maintenance, which includes inspections, servicing, handling, preventive and corrective maintenance, and Intermediate Maintenance, which includes assembly and disassembly beyond the capability of the organizational level. Depot-level maintenance includes any action performed on materiel or software in the conduct of inspection, repair, overhaul, or the modification or rebuild of end-items, assemblies, subassemblies, and parts. Depot level maintenance generally requires extensive industrial facilities, specialized tools and equipment, or uniquely experienced and trained personnel that are not available in lower echelon-level maintenance activities.

General Information

DoD maintenance is accomplished by two different yet complementary components — depot-level and field-level maintenance activities. The two components are distinguished largely by their relative capabilities, flexibility, agility, and capacity.


According to the Office of the Assistant Secretary of Defense for Sustainment (OASD (Sustainment)) website, field-level has two primary aspects: on-equipment (also called organizational) and shop-type (also called intermediate). These aspects may be viewed as “sub-levels.” Specifically field level maintenance includes:

  • On-equipment (organizational) - Joint Publication (JP) 1-02, DoD Dictionary of Military and Associated Terms, describes organizational maintenance as that maintenance that is the responsibility of and performed by a using organization on its assigned equipment. Its phases normally consist of inspecting, servicing, lubricating, and adjusting, as well as the replacing of parts, minor assemblies, and subassemblies. Of note is that organizational-level maintenance describes work performed in the field, on the flight line, or at the equipment site, and is not only accomplished by maintenance personnel, but also by equipment operators.
  • Shop Type (Intermediate) - JP 1-02 defines intermediate maintenance as that maintenance that is the responsibility of and performed by designated maintenance activities for direct support of using organizations. Its phases normally consist of: calibration, repair, or replacement of damaged or unserviceable parts, components, or assemblies; the emergency manufacture of non-available parts; and providing technical assistance to using organizations.

In essence field-level maintenance comprises shop-type work as well as on-equipment maintenance activities at maintenance levels other than depot. Intermediate or shop-type work includes: limited repair of commodity-oriented assemblies and end items (e.g., electronic “black boxes” and mechanical components); job shop, bay, and production line operations for special requirements; repair of subassemblies such as circuit boards; software maintenance; and fabrication or manufacture of repair parts, assemblies, and components. On-equipment or organizational maintenance is normally performed by an operating unit on a day-to-day basis to support operations of its assigned weapon systems and equipment. Organizational maintenance encompasses a number of categories, such as inspections, servicing, handling, preventive maintenance, and corrective maintenance. Although no set of financial management systems captures the total cost of field-level maintenance, it is currently estimated to be in the range of $45 billion annually.


Defined in Title 10 USC 2460 as material maintenance or repair requiring overhaul, upgrading, or rebuilding of parts, assemblies, or subassemblies, and the testing and reclamation of equipment as necessary, regardless of the source of funds or the location at which the maintenance or repair is performed. According to this statute, the term depot-level maintenance includes:

  1. All aspects of software maintenance classified by the DoD as of July 1, 1995, as depot-level maintenance and repair
  2. Interim contractor support or Contractor Logistics Support (CLS) (or any similar contractor support), to the extent that such support is for the performance of services described in the preceding sentence

Also according to 10 USC 2460, however, there are two exceptions:

  1. The term does not include the procurement of major modifications or upgrades of weapon systems that are designed to improve program performance or the nuclear refueling or defueling of an aircraft carrier and any concurrent complex overhaul. A major upgrade program covered by this exception could continue to be performed by private or public sector activities.
  2. The term also does not include the procurement of parts for safety modifications. However, the term does include the installation of parts for that purpose.

Also according to the OASD(Sustainment) website, depot-level maintenance entails materiel maintenance requiring the major repair, overhaul, or complete rebuilding of weapon systems, end items, parts, assemblies, and subassemblies; manufacture of parts; technical assistance; and testing. Each military service manages and operates its own organic depot-level maintenance infrastructure. The bulk of the workload — about 86 percent — is associated with ships, aircraft and missiles. Aircraft and missile work amounts to about 58 percent of the total while ship work accounts for about 28 percent. The remaining work includes combat vehicle, tactical vehicle, and other ground equipment system workloads. For FY 2016, DoD spent nearly $32 billion for depot-level maintenance and repair work. Approximately 55 percent of the Department's FY 2014 depot-level workload was accomplished in organic facilities; the remainder was done in the private sector — by commercial firms.

Application to Specific Weapon Systems

DoD Directive 4151.18, Maintenance of Military Systems  requires that maintenance programs allocate tasks to appropriate levels of maintenance based on criteria derived from warfighter requirements and cost-effective analysis. The application of specific maintenance levels/sub-levels, however, varies from weapon system to weapon system, and is driven by Service policy, the maintenance concept of the weapon system, and the technological complexity of the weapon system. Most repairable DoD weapon systems and equipment require both field- and depot-level maintenance.

In regard to field-level maintenance, however, some weapon systems are subject to the intermediate sub-level, while others are not. In other words, the maintenance concept for some weapon systems provides for organizational, intermediate and depot-level tasks (O-I-D), while other weapon systems require only organizational and depot-level (O-D) tasks. Once this aspect of the maintenance concept is determined, the allotment of maintenance tasks to the various levels/sub-levels is determined by an analytical process known as Level of Repair Analysis (LORA). The LORA process takes both economic and non-economic factors into account in arriving at recommended levels of repair for a system/end item and all of its repairable components.