There are three levels at which maintenance is performed on aircraft that the United States Navy has in inventory at any given time: organizational, intermediate and depot. Each performs a specific function or serves a purpose such that anything required for the aircraft to be maintained in a fully operational status 365 days a year is immediately attended to with the utmost regard to quality and safety. Some repairs being either too time consuming or requiring expertise outside of the level is one of the primary reasons why maintenance is broken down into this three-part system.

Maintenance of this type is defined by the efforts necessary required by a specific unit on a day-to-day basis to keep an airframe in an operational condition. In addition to the requirement of maintaining assigned aircraft and aeronautical equipment in a full mission capable status, O-level is also responsible for the continual improvement of the local maintenance process.

Maintenance required in support of operational activities. This includes the repair of specific parts unable to be refurbished at the organizational level and detailed maintenance of electronic components requiring specific equipment not peculiar to O-level. I-level is also responsible for maintaining a constant flow of necessary materials to operational assets with the lowest possible cost expenditure in order to maximize efficiency.

Occasionally in depth maintenance or complex repairs on an airframe are required to maintain equipment in an operational status. Depot level repairs would include major alterations or refurbishing of an asset due to age or upgrade far beyond the capabilities of the organizational level requiring industrial facilities not available elsewhere. Special Depot Level Maintenance (SDLM,) commonly perform overhaul operations on airframes in need of such attention.