Which of the following is NOT one of the six annunciators relating to fuel systems?

The correct answer is associated with recognizing the standard annunciator colors and functions in the T-6A fuel system. In this case, "Red FUEL HIGH" is not one of the standard annunciators related to fuel systems. The primary function of annunciators is to alert pilots to specific conditions or statuses, and they are categorized by color coding indicating the severity or nature of the alert.

Typically, the red annunciators, such as "Red FUEL PX," usually indicate a critical issue that requires immediate attention, while amber alerts like "Amber FUEL LO" signify cautionary conditions, such as low fuel levels that still allow for operational considerations. The "Green BOOST PUMP" indicates a normal operational condition where the boost pump is functioning properly.

In summary, the "Red FUEL HIGH" annunciator does not fit within the established system parameters for alerting pilots positively or negatively about the fuel conditions, confirming it as the correct choice in identifying which option does not belong among the announcements related to fuel systems.