Commercial Pilot License (CPL) Practice Exam 2025 - Free Commercial Pilot License Practice Questions and Study Guide

The option highlighting retractable landing gear exemplifies hydraulic equipment on an aircraft because it operates using hydraulic systems to extend and retract the landing gear. Hydraulic systems are commonly used in aircraft for various functions requiring substantial force, as they can transmit power over distances without needing excessive mechanical components.

Hydraulic systems in landing gear are advantageous due to their reliability and the ability to efficiently manage and control movement, especially during critical phases of flight, such as takeoff and landing. These systems generally include hydraulic pumps, actuators, and associated lines that seamlessly operate the mechanism, ensuring swift deployment and retraction.

The other options represent different systems or mechanisms: electrically-operated flaps rely on electrical power rather than hydraulic pressure; mechanical ailerons utilize a direct mechanical connection for control, not hydraulic systems; and the static air pressure system is involved in measuring air pressure for altitude and speed but does not pertain to hydraulic operation. Understanding the role of hydraulic systems in landing gear helps grasp fundamental aircraft design and safety features.