Which of the following defines preventive maintenance?

Preventive maintenance is best defined as the normal upkeep of aircraft systems. This type of maintenance aims to ensure that the systems are functioning optimally and to prevent potential issues from developing. It involves regular checks, servicing, and minor repairs conducted on a systematic basis to prolong the life of the equipment and reduce the likelihood of unexpected failures.

The focus is on maintaining functionality and safety rather than responding to emergencies, which distinguishes it from other practices. While planned maintenance relates closely to preventive measures, the essence of preventive maintenance is about ongoing upkeep rather than merely planning.