What does FDR MAINT indicate?

The indication that FDR MAINT reflects a scenario where IDARS (Integrated Data Acquisition and Reporting System) is 80% full or has reached an over-limit condition is crucial for safety and operational maintenance protocols. When this level is reached, it suggests that the data storage is nearing capacity, which could hinder the system's ability to record essential flight data.

The operational management of an aircraft relies heavily on the IDARS for recording flight data, and exceeding its capacity can lead to data loss or failure to capture critical information that may be needed for analysis in events such as accidents or system failures. Notifying maintenance at this stage allows for proactive measures to either clear existing data or address potential issues before they escalate, ensuring the system remains functional and reliable.

Thus, being aware of the FDR MAINT signal is essential for maintaining aircraft integrity and operational safety. Other options pertain to different systems or conditions that do not directly relate to the capacity status of IDARS, hence they do not accurately represent the assertion of FDR MAINT.