According to Federal Aviation Regulations, what must aircraft using fuses as circuit protective devices carry?

Aircraft using fuses as circuit protective devices are required to carry one spare set of fuses, or three spare fuses of each kind, as stipulated by Federal Aviation Regulations. This requirement ensures that in the event of a fuse failure, the aircraft has the necessary components readily available to maintain operational safety and functionality.

Fuses serve as critical safety devices that protect electrical circuits from overcurrent conditions that could lead to equipment damage or fire. By having a sufficient number of spare fuses on board, pilots and maintenance crews can quickly replace any blown fuses without compromising the aircraft's operations or safety. This provision is an essential aspect of the regulations aimed at ensuring the reliability and safety of aircraft electrical systems.

Choosing to carry one spare circuit breaker or two spare circuit boards does not meet the specified requirements for aircraft using fuses, as they relate to different types of protective devices. Likewise, the option stating that no spare parts are required fails to emphasize the importance of readiness in maintaining electrical integrity during flight operations.