Which maintenance level is considered the lowest?

O-level maintenance, or Organizational Maintenance, is considered the lowest maintenance level in the military aviation maintenance structure. This level is primarily performed by the operating units themselves and is focused on minor repairs, routine checks, and servicing of equipment and systems to ensure that operational readiness is maintained.

At the O-level, personnel are responsible for conducting inspections, replacing components, and performing minor repairs on aircraft and related systems. This maintenance is critical because it directly supports flight operations by enabling the aircrew to have fully functional and ready aircraft at all times.

In contrast, higher maintenance levels, such as I-level (Intermediate-level) and Depot Level Maintenance, involve more complex repairs, overhauls, and modifications that require specialized facilities, tools, and more advanced support and resources. These levels typically dive deeper into the technical and structural integrity of the aircraft, which is not feasible at the O-level due to the limited resources and capabilities of the operating units.