How is thrust indicated on a turbofan engine?

Thrust in a turbofan engine is primarily indicated by the engine pressure ratio, which is the ratio of the pressure at the engine's inlet to the pressure at the exhaust. This measurement is crucial because it correlates directly with the performance and efficiency of the engine. A higher engine pressure ratio typically indicates that the engine is producing more thrust, as it means that the engine is able to compress the incoming air and generate a larger difference in pressure, leading to greater acceleration of the exhaust gases—ultimately translating to higher thrust.

The other options, while related to engine performance, do not provide a direct indicator of thrust. The maximum RPM of the turbofan does give an idea of engine speed, but it doesn't account for the thrust produced directly. Temperature differentials across the turbine can indicate efficiency and operational health but do not directly measure thrust. Finally, the fuel consumption rate is more a measure of efficiency rather than a direct indicator of thrust output. Thus, engine pressure ratio is the most reliable indicator of turbofan engine thrust.