What effect does the loss or deactivation of PMU function have on the system?

• A. It activates automatic reset functionality
• B. It disables the aircraft's electronics
• C. It resets to modulate oil pressure to maintain Np at or below 100+/-2%
• D. It enhances engine performance

Answer: (C)

The loss or deactivation of PMU (Propulsion Management Unit) function impacts the aircraft’s ability to manage engine parameters effectively. When the PMU is functioning, it regulates various engine parameters, including maintaining the rotational speed (Np) of the engine at optimal levels. When the PMU is lost or deactivated, the PMU's automatic adjustments to modulate oil pressure in order to keep Np at or below 100 +/- 2% are also lost.

This modulation is crucial in ensuring that the engine operates within safe limits and prevents potentially harmful conditions. Without the PMU’s supervision, the system reverts to manual control, which may not automatically adjust for fluctuations in operating parameters, emphasizing the importance of the PMU in maintaining mechanical reliability and engine performance.

The other options are not applicable in this context. For instance, automatic reset functionality and enhancements in engine performance are not terms directly related to the consequences of PMU loss; rather, the PMU would help prevent malfunction and maintain performance stability. Disabling the aircraft's electronics does not accurately represent the function of the PMU, as it primarily focuses on engine management rather than complete electronic failure.