Which maintenance level performs extensive repairs and modifications?

The correct choice for which maintenance level performs extensive repairs and modifications is depot level maintenance. This level of maintenance is specifically designed to handle complex and significant repairs that are beyond the capabilities of the lower maintenance levels, such as organizational and intermediate levels. Depot level maintenance facilities are equipped with the necessary infrastructure, tools, and skilled personnel to undertake major overhauls, upgrades, and modifications of aircraft and aviation systems.

The nature of depot level work often involves the following tasks: replacement of major components, complete system overhauls, heavy modifications that require extensive resources, and systematic renovations to bring systems up to the latest standards and capabilities. This level of maintenance is critical for ensuring the longevity and operational readiness of aircraft within the fleet.

In contrast, organizational level maintenance focuses on the routine checks and repairs that can be performed by flight line personnel, while intermediate level maintenance deals with more complex tasks than organizational maintenance but is not equipped for the extensive repairs handled at the depot level. Field level maintenance typically refers to actions taken to address immediate issues in a deployed environment, which is much less extensive than depot level maintenance activities.