In which scenario would a standard maintenance procedure be considered a major alteration?

A standard maintenance procedure is classified as a major alteration when it significantly changes the configuration of an aircraft, typically affecting its structure, performance, or operational capabilities. Installing a new radio system fits this definition, as it is not merely a replacement of components but involves integrating new technology that could impact the aircraft's communication systems and might require alterations in the wiring, control functionality, and possibly the aircraft's weight and balance.

In contrast, replacing a standard tire is routine maintenance that does not alter the aircraft's design or performance. Changing the oil in the engine is a standard maintenance procedure focusing on the engine's ongoing operation and does not affect its configuration. Adjusting control surfaces, while it influences the aircraft's handling, generally falls under regular maintenance practices that do not constitute a major alteration unless significant structural changes are involved.