Which Federal Aviation Regulation specifies that each resettable circuit protective device requires a manual operation to restore service?

The correct choice relates to 14 CFR Part 23, which establishes detailed requirements for aircraft of small passenger and cargo capacities. This regulation specifies that each resettable circuit protective device within the aircraft must necessitate manual operation to restore service after it has tripped or interrupted power. This safety requirement is critical as it ensures that pilots or maintenance personnel are actively aware of the circuit interruption and can assess the situation before restoring power. This requirement enhances operational safety by preventing inadvertent restarts of systems that may be malfunctioning, thus avoiding potential hazards.

Other parts mentioned, such as Part 25, 43, and 91, address different aspects of aviation safety and operations, but they do not include the specific regulations concerning the operation of resettable circuit protective devices as outlined in Part 23. Part 25, for instance, pertains to airworthiness standards for transport category airplanes, while Part 43 focuses on maintenance, preventive maintenance, rebuilding, and alteration of aircraft. Part 91 includes general operating and flight rules. Each of these parts has its domain within aviation regulations but does not cover the specific requirement for manual restoration of circuit devices found in Part 23.