Which of the following constitutes a propeller major repair?

In the context of propeller maintenance, both the straightening of steel blades and the repair of a propeller governor are considered major repairs. A major repair is defined as a repair that, if not performed correctly, could significantly affect the structural integrity and operational capability of the propeller, which is critical for the safety of the aircraft.

Straightening of steel blades involves altering the physical properties of the blades and requires specialized techniques to ensure that the blades maintain their balance, strength, and aerodynamics after repair. This process can significantly impact the performance and durability of the blades, thereby categorizing it as a major repair.

Similarly, the repair of a propeller governor also qualifies as a major repair because the governor is essential for controlling the pitch of the propeller blades and maintaining the correct engine RPM. Any failure to operate correctly can directly affect flight safety. Repairs to such critical components necessitate adherence to strict standards and practices, further justifying their classification as major repairs.

By identifying that both shown actions fall under the definition of major repairs, the correct choice reflects the comprehensive understanding of the maintenance requirements associated with propeller systems.