The N2 Indicator is an essential gauge found in aircraft cockpits. It typically shows the rotational speed of the high-pressure engine spool, commonly referred to as N2. In engines with three spools, like the Rolls Royce RB211, N2 indicates the intermediate pressure spool. This gauge is usually calibrated to represent percent RPM, with the manufacturer defining what constitutes 100% rotational speed. Depending on the aircraft’s design, the N2 Indicator may exist as a standalone analog or digital gauge. Alternatively, its data can be integrated into systems like the Engine Indicating and Crew Alerting System (EICAS) or the Electronic Centralized Aircraft Monitor (ECAM).
