What is the main difference between an annual inspection and a 100-hour inspection?

The main distinction between an annual inspection and a 100-hour inspection lies in the frequency and regulatory requirements associated with each type of inspection. An annual inspection is required to be conducted once every 12 calendar months, regardless of the number of flight hours accrued, making it a more extensive review that confirms the overall airworthiness of the aircraft for the entire year.

On the other hand, a 100-hour inspection is specifically mandated for aircraft that are used for hire, including those engaged in flight training operations, and must be performed every 100 flight hours. While both inspection types include many similar tasks and checks, the annual inspection typically includes a thorough examination of the entire aircraft, while the 100-hour inspection often has a more focused scope aligned with operational use.

Thus, the correct answer emphasizes the difference in time intervals, highlighting that each inspection type serves distinct operational needs within aviation maintenance requirements.