Which of the following is classified as an airframe major repair?

The classification of an airframe major repair typically involves modifications or repairs that significantly affect the aircraft's structure or its supporting elements. Repairing skin sheets by adding seams falls into this category because it involves altering the aircraft's outer skin structure, which is crucial for its aerodynamic integrity and overall safety.

In aviation, the skin of the airframe plays a vital role in the structural integrity and performance of the aircraft. When seams are added to the skin sheets, it may not only restore the original condition but also facilitate structural loads and influences how the aircraft responds to flight dynamics. This kind of repair can require extensive work and often needs to be performed under specific guidelines and standards set forth by aviation regulatory bodies, highlighting its major impact on the airframe.

In contrast, replenishing oil typically falls under routine maintenance rather than major structural repairs. Changes to the wing or control surfaces affecting flutter and vibration, while significant, may not be classified strictly as airframe repairs in the same manner as skin sheet repairs—this option is more focused on performance rather than structural integrity. Rewinding the field coil of an electrical accessory pertains to electrical systems and does not affect the airframe directly, thus not qualifying as a major airframe repair.

Overall, adding seams to skin sheets