Aircraft instrument values should be marked and graduated according to what?

The correct answer emphasizes the importance of following guidelines outlined in either the specific aircraft maintenance manual or the specific flight manual when marking and graduating aircraft instrument values. Each manual contains critical information pertinent to that specific aircraft model, ensuring that instrument readings are accurate, reliable, and consistent with the operational limits and performance data established by the manufacturer.

Using these manuals helps to standardize procedures across aircraft of the same model, contributing to a higher level of safety and maintenance efficacy. They are designed to provide technicians and pilots with clear instructions that are tailored to the specific operating characteristics and requirements of the aircraft in question.

While industry standard guidelines may offer general recommendations, they do not account for the unique specifications of each aircraft type. Thus, choosing either the maintenance or flight manual guarantees the correctness and relevance of the information directly applied to the aircraft being used.