Which engine indication is used for trimming a turbine engine?

The engine performance ratio (EPR) is the correct indication to use for trimming a turbine engine. EPR is a measure of the efficiency of the engine, representing the ratio of the engine's exhaust pressure to the inlet pressure. It provides critical insights into the balance and overall performance of the engine.

Trimming an engine involves adjusting the fuel flow or other parameters to ensure optimal performance and efficiency, particularly during different phases of flight. By monitoring the EPR, pilots can ensure that the engine is producing the desired thrust relative to its power input. This ensures that the engine operates safely within its performance limits while delivering the required power for the flight conditions.

In contrast, while fuel flow rate, torque output, and oil pressure provide valuable information about the engine's operation and health, they do not directly indicate how well the engine is performing relative to its intended power output and thrust generation. Thus, EPR is the most relevant measurement for trimming purposes in turbine engines.