Which statement is true concerning required maintenance inspections?

The statement that an annual inspection may be substituted for a 100-hour inspection is accurate. In the context of aircraft maintenance, the 100-hour inspection is specifically required for aircraft that are used in passenger-carrying operations for hire or flight instruction for hire, while the annual inspection is a broader, more comprehensive review of the aircraft's condition that must be performed at least once every 12 months regardless of usage.

If an aircraft reaches 100 flight hours within a 12-month period, it would typically require a 100-hour inspection unless an annual inspection has already been conducted. In such cases, the annual inspection can cover the requirements of the 100-hour, satisfying regulatory obligations as long as it occurred within that timeframe.

Therefore, the option that states an annual inspection can substitute for a 100-hour inspection under specified conditions reflects an understanding of the regulatory framework governing aircraft maintenance.