What happens when either FLT CONTROL switch is positioned to STBY RUD?

• A. The hydraulic system is turned off
• B. The standby system uses a motor-driven pump
• C. The main pump runs continuously
• D. The system switches to manual control

Answer: (B)

When the FLT CONTROL switch is positioned to STBY RUD, the correct outcome is that the standby system uses a motor-driven pump. This scenario typically occurs in a hydraulic system designed for redundancy, where the standby system becomes operational to ensure continued functionality in critical systems, such as rudder control, in case of an issue with the primary hydraulic system.

The use of a motor-driven pump allows for the standby system to operate independently of the main hydraulic pumps, ensuring that essential flight controls remain functional even if there is a failure in the main hydraulic system. This design is particularly important in aviation, where reliability and safety are paramount, as it provides an alternative source of hydraulic pressure to maintain control over critical flight surfaces.

In this context, options suggesting that the hydraulic system is turned off, the main pump runs continuously, or that the system switches to manual control do not accurately reflect the operation of hydraulic systems in standby modes. Those scenarios imply either a complete loss of hydraulic functionality or do not utilize the redundancy designed into the system, which is critical for maintaining aircraft control and safety.