In which two specific conditions is the emergency hydraulic system used?

The emergency hydraulic system is specifically designed to provide functionality when there is a loss of engine power or a primary hydraulic system failure. In such scenarios, the regular hydraulic system, which is powered by engine-driven pumps, may become inoperative. The emergency hydraulic system, therefore, serves as a backup to ensure that critical flight control surfaces remain operable and that the pilot can maintain control of the aircraft.

Utilizing this system during an engine failure or primary system failure is crucial for safety, as it helps the pilot in managing the aircraft's landing and other emergency operations. The correct answer highlights the importance of redundancy in aircraft systems, particularly regarding hydraulics, to enhance safety during critical situations.

Other conditions presented in the options do not pertain to the activation of the emergency hydraulic system. For instance, low fuel state or engine overheating does not inherently cause the hydraulic systems to fail. Similarly, excessive altitude or high airspeed concerns primarily focus on aerodynamic performance rather than hydraulic functionality. Lastly, while a hydraulic leak might suggest a malfunction, it is not classified as one of the specific conditions for using the emergency hydraulic system compared to a complete loss of engine power or the primary system. Thus, the selection of the first option is aligned with the intended operational use of