Which maintenance level primarily involves inspecting and servicing aircraft parts?

The O-level, often referred to as Organizational level maintenance, is primarily focused on the day-to-day upkeep and operational readiness of aircraft. This maintenance level emphasizes inspecting and servicing aircraft parts to ensure they function properly and meet safety standards. Routine checks, minor repairs, and preventive maintenance are typical tasks performed at this level, making it crucial for the operational efficiency of aircraft.

In contrast, I-level maintenance typically involves more in-depth repairs and maintenance tasks that require specialized skills and equipment, while D-level or Depot level maintenance is reserved for extensive repairs and overhauls that may not be feasible at the O-level or I-level. Such tasks might include complete aircraft refurbishments or significant structural repairs, which are beyond simple inspections and servicing. Therefore, the focus of the O-level on inspection and servicing is what makes it the correct choice in this case.