What does the N1 gauge indicate in an aircraft?

The N1 gauge is specifically designed to measure the rotation speed of the low pressure engine spool in a gas turbine engine. This is crucial for the operation of the aircraft's engines, as it provides pilots and engineers with real-time feedback on the performance and efficiency of the engine. The N1 measurement is expressed as a percentage of the maximum allowable speed, allowing for monitoring of optimal engine performance during various phases of flight.

Understanding N1's significance helps ensure that the engine is operating within safe limits and can also indicate potential issues if the expected rotation speed deviates from normal parameters. Consequently, maintaining the correct N1 readings is vital for flight safety and operational efficiency.