Which engine parameter is primarily used to set thrust?

The primary engine parameter used to set thrust is N1, which refers to the speed of the low-pressure compressor in the engine. In turbofan engines, N1 is a crucial indicator because it is directly linked to the engine's thrust output. As N1 increases, the amount of air moving through the engine and the speed of exhaust gases also increase, resulting in greater thrust being produced.

In the context of engine operation, adjusting N1 allows pilots to effectively control thrust during different phases of flight, such as takeoff, climb, and cruise. Thus, monitoring and setting N1 appropriately is essential for optimizing performance and ensuring safety.

The other options, while relevant to engine performance, do not primarily determine thrust levels in the same way. EGT (Exhaust Gas Temperature) and RPM (Revolutions Per Minute) are important for monitoring engine health and operational limits, but they do not set thrust directly. N2 represents the speed of the high-pressure compressor and is also a factor in overall engine performance, but it is the N1 parameter that is most commonly referenced in relation to setting thrust during engine operation.