When do the LOW PRESSURE lights below the FLT CONTROL A and B switches illuminate?

• A. During normal operation of the system
• B. When hydraulic pressure is low to flight control surfaces
• C. When the landing gear is being raised
• D. When the emergency system is activated

Answer: (B)

The LOW PRESSURE lights below the FLT CONTROL A and B switches illuminate when hydraulic pressure is low to the flight control surfaces. This is an important safety feature designed to alert the flight crew that there may be a problem with the hydraulic system responsible for controlling the aircraft's flight surfaces. When hydraulic fluid pressure drops below specific thresholds, it can compromise the performance and responsiveness of these critical flight systems.

Understanding this mechanism helps ensure that pilots can take appropriate action if the lights indicate a drop in hydraulic pressure, which may include checking the hydraulic system status and determining if alternate operating methods or emergency procedures need to be initiated to maintain control over the aircraft.

The other options describe scenarios that do not directly cause the illumination of the LOW PRESSURE lights. For example, normal operation should not trigger the lights, raising the landing gear does not inherently relate to flight control pressure, and the activation of the emergency system pertains to different indicators and systems within the cockpit.