Which of the following is classified as a major repair?

The classification of a major repair is often based on the significance and complexity of the work involved, as well as the impact it has on the overall airworthiness of the aircraft.

The splicing of skin sheets is considered a major repair because it involves the structural integrity of the aircraft. Skin sheets are the outer panels that cover the fuselage or wings, and altering or replacing these requires extensive work and careful consideration of engineering standards. Such repairs can directly impact the aircraft’s aerodynamics, strength, and overall safety.

In contrast, the other options, while they may require skilled labor and attention, typically do not alter the aircraft's fundamental structure. For example, the replacement of a wheel falls under routine maintenance and may not require a major repair designation, as it is a component that can be easily replaced without affecting the aircraft’s overall structural integrity. Similarly, painting and adjusting control surfaces are often classified as routine upkeep rather than major repairs, as they do not involve significant alterations to the aircraft's structural components.