Which of the following is an indication of PMU failure?

The indication of PMU (Power Management Unit) failure that stands out is the power step change. This refers to a sudden and unexpected change in engine power output, which can occur if the PMU fails to regulate the engine's performance correctly. The PMU is responsible for managing various parameters of the engine to ensure optimal performance and safety, and any malfunction in this system can lead to erratic power levels.

In contrast, fluctuating oil pressure, excessive turbine temperature, and rapid decay of N1 can be symptoms of other issues within the engine system but are not definitive indicators of PMU failure. Fluctuating oil pressure typically points to lubrication system issues, while excessive turbine temperature can indicate problems such as over-temperature conditions during engine operation. Rapid decay of N1, which refers to the speed of the engine's compressor, may suggest issues with the engine’s mechanical system or fuel delivery rather than a direct failure of the PMU. Each of these symptoms can arise from various causes and may not specifically signal PMU failure.

Thus, a power step change is the most directly associated with PMU failure, highlighting the critical role this component plays in maintaining stable engine performance.