A holder of an inspection authorization must prove what for compliance?

The requirement for a holder of an inspection authorization (IA) to have performed at least four annual inspections in the previous two years ensures that the individual maintains an adequate level of practical experience and current knowledge in the realm of aircraft inspections. This experience is essential because annual inspections are complex processes that assess the airworthiness of an aircraft and adhere to regulatory standards set by the FAA. By requiring a specific number of inspections, the regulation emphasizes the importance of hands-on practice, which is critical for understanding the nuances of various aircraft systems and compliance with safety protocols.

The other options, while they may seem relevant to maintenance and inspection knowledge, do not directly address the requirements established for maintaining an IA. Training in major repairs, completion of maintenance courses, and managerial endorsements are certainly beneficial but they do not replace the practical check of having actively engaged in the inspection process itself within the required time frame. This focus on actual inspection experience is vital for ensuring that the IA holder is well-equipped to uphold the rigorous standards mandated for aircraft safety.