Which maintenance level is NOT associated with the performance of major overhauls?

The O-level maintenance is primarily focused on organizational or intermediate-level tasks that are necessary for day-to-day operations. This level typically includes routine maintenance, inspections, and minor repairs conducted by ground personnel. It is designed to ensure equipment is safe and operational but does not involve the extensive repairs or overhauls that are required at higher maintenance levels.

In contrast, I-level maintenance involves more complex maintenance tasks, including calibration, repair, and major systems checks. This level can perform significant overhauls and maintenance that cannot be done at the organizational level. D-level maintenance, often referred to as depot-level maintenance, encompasses the most significant repairs, including complete overhauls and significant modifications, large-scale repairs, and extensive overhauls performed at a dedicated facility.

Maintenance level four refers to specific categories of maintenance procedures but does not imply a maintenance level with its own unique capabilities separate from the established levels of O, I, and D. Thus, within the context of maintaining and overhauling aircraft, O-level maintenance is the correct choice as it does not perform major overhauls.