What indicates that a turbofan or turbojet engine is out of trim?

A turbofan or turbojet engine being out of trim is indicated by a high exhaust gas temperature (EGT) at a target engine pressure ratio for takeoff power. This condition reflects an imbalance within the engine's operation, which can result from several issues, such as airflow disruptions, improper fuel-air mixture, or mechanical misalignments.

When an engine is properly trimmed, it operates within its designed parameters, resulting in expected performance. A high EGT at a given pressure ratio indicates that the engine is producing excess heat relative to the power it is generating, which is a sign of inefficiency or a performance anomaly. This condition could lead to potential engine damage if not addressed, as it signifies that the engine is not functioning optimally.

Regarding the other choices, while low power output, increased fuel consumption, and unstable engine speed may also indicate potential issues with the engine, they do not specifically provide the direct indication of being out of trim in the same manner that a high EGT at a set engine pressure ratio does. These conditions may stem from various factors unrelated to an engine's trim status.