Which of the following is not part of line maintenance?

• A. Inspections
• B. Parts replacement
• C. Repairs
• D. On-aircraft overhaul

Answer: (D)

Line maintenance covers the day-to-day, on-the-spot tasks that keep the aircraft safe and airworthy during operations at the ramp. It includes inspections to verify condition, replacing worn or defective parts as needed, and performing repairs that can be completed quickly without removing the aircraft from service. On-aircraft overhaul, by contrast, is a much more extensive, specialized activity that involves deeper teardown and rebuild work, usually done in a shop or hangar during scheduled heavy maintenance. It requires more time, tooling, and facilities, and can take the aircraft out of service for a longer period. That’s why it isn’t considered part of line maintenance.