Final answer:
The program is called structural repair and modification program and involves restoring or replacing primary aircraft structures that have reached fatigue life limits.
Step-by-step explanation:
The program that focuses on the restoration or replacement of primary aircraft structures that have reached fatigue life limits is called structural repair and modification program.
During the normal operation of an aircraft, its primary structures, such as wings, fuselage, and landing gear, are subjected to cyclic loading and stresses that can eventually lead to fatigue cracks and failures. When these structures reach their fatigue life limits, they need to be repaired or replaced to ensure the safety and integrity of the aircraft.
The structural repair and modification program involves assessing the extent of damage, developing repair procedures, and carrying out structural repairs or part replacements. Highly skilled engineers and technicians work on this program, following strict guidelines and regulations to maintain the airworthiness and reliability of the aircraft.