3F Airplane Systems - Hydraulic System

Question 0

2. What provides hydraulic power to the landing gear system?

Answer 0

An electrically-driven hydraulic power pack provides all hydraulic power to the landing gear system. The power pack is located behind the firewall between the pilot’s and copilot’s rudder pedals.

Question 1

1. What equipment would be considered hydraulic on this aircraft?

Answer 1

a. The retractable landing gear
b. The emergency hand pump
c. The hydraulically-actuated brake on each main gear
d. The air/oil nose gear shock strut

Question 2

3. Describe hydraulic power pack operation.

Answer 2

Hydraulic power pack operation is controlled by the landing gear lever. When the gear lever is selected in either the “Up” or “Down” position, a pressure switch will activate the power pack and a selector valve is mechanically rotated. Depending on the position of the landing gear lever (and corresponding valve position), hydraulic pressure will be applied in the direction selected. This hydraulic pressure is applied to actuator cylinders, which extend or retract the gear. When the landing gear has reached the desired position and the cycle is complete (a series of electrical switches have closed or opened), an indicator light will illuminate on the panel. In the “Gear Down” cycle only, the hydraulic power pack will continue to operate until system pressure is between 1,000 PSI to 1,500 PSI, at which time the pressure switch turns the power pack off. The hydraulic system normally maintains an operating pressure of 1,000 PSI to 1,500 PSI.