Ace the TH-73A Systems Exam 2026 – Soar to Success with Confidence!

The measurement of N2 speed (which refers to the speed of the second stage of a two-spool engine) is indeed taken using an electronic speed sensor located in the engine reduction gearbox (RGB). This sensor is crucial for providing accurate and real-time data about the engine's performance and operational status.

The electronic sensor captures the rotational speed of the N2 spool, which is vital for monitoring and controlling the engine's performance across various phases of operation. Consequently, knowing the N2 speed is essential for ensuring the engine runs within its safe operational limits and for optimizing performance.

Other phases of operation, such as ground idle or startup, do not specifically pertain to how the N2 speed is measured; rather, they denote distinct operating conditions where the N2 speed will still be continuously monitored by the electronic sensor.