Hydraulics

Question 1

How do you identify hydraulic lines on an aircraft? **

Answer 1

Tape with the word hydraulics on a field of blue (on the left) and yellow with black circles (on the right.)

Question 2

What ppe must be worn when working with hydraulic fluid?

Answer 2

Gloves, goggles, or face shield.

Question 3

What aircraft components largely depend on hydraulics for operation?

Answer 3

Landing gear, flaps, flight control surfaces, and brakes.

Question 4

What law applies to hydraulic systems? Give a brief overview.

Answer 4

Pascal’s Law- pressure in an enclosed container is transmitted equally and undiminished to all points of the container and the force acts at right angles to the enclosing walls.

Question 5

What theory applies to hydraulic systems? Give a brief overview.

Answer 5

Bramah’s Theory- a small amount of force applied to a small area creates a proportionally larger force on a larger area. Input and output forces are proportional to the size of the piston area.

Question 6

What are the two types of reservoirs used in CG aviation hydraulics, and how are they provide constant fluid flow?

Answer 6

Nonpressurized- atmospheric pressure and gravity. Pressurized- compressed air or pressurized fluid, applied against a piston.

Question 7

What is the filter element of a hydraulic filter made of?

Answer 7

Stainless steel wire mesh or disposable pleated paper.

Question 8

How are filter elements measured?

Answer 8

Microns- one micron being 1 millionth of a meter, or 39 millionths of an inch.

Question 9

What are the 4 types of hydraulic pumps used on CG aircraft?

Answer 9

Double-Acting Action Hand Pump, Piston-Type Variable Displacement Power-Driven Pump, Gear-Type Constant Displacement Power-Driven Pump, and Piston-Type Constant Displacement Pump

Question 10

Give a brief description of double action hand pumps.

Answer 10

to supply fluid to subsystems, used on most hand operated ground support equipment.

Question 11

Give a brief description of variable displacement piston pumps.

Answer 11

(controls hydraulic fluid by the demands of the system.) nine piston pump powered at the drive coupling by an engine, accessory gearbox, or electric motor.

Question 12

Give a brief description of Gear-type constant displacement pumps.

Answer 12

power-driven, delivers a constant volume of fluid. Installed into spline of an aircraft engine or other power unit

Question 13

Give a brief description of piston-type constant displacement pumps.

Answer 13

powered at drivecoupling shaft by engine, gearbox, or electric motor. supplies continuous flow of fluid.

Question 14

What types of valves are used in hydraulic systems?

Answer 14

Selector Valves, Check Valves, Orifice type Check valves, sequence valves, and quick disconnect valves.

Question 15

What is the most durable and trouble-free selector valve in use?

Answer 15

Slide-type

Question 16

What is the purpose of a selector valve?

Answer 16

A flow control valve that directs pressurized fluid into one side of an actuator, and at the same time directs return fluid from the other side of the actuator into the reservoir.

Question 17

What is the purpose of check valves?

Answer 17

Allows full flow of fluid in one direction but blocks all flow in the opposite direction.

Question 18

What is the purpose of an orifice-type check valve?

Answer 18

Allows unrestricted flow in one direction, and restricted flow in the opposite direction. (also used in pneumatics)

Question 19

What is the purpose of a sequence valve?

Answer 19

Requires a certain action to be completed before another can begin, used to assure hydraulically actuated wheel-well doors are completely open before pressure is directed to the landing gear to lower it.

Question 20

What is the purpose of quick disconnect valve?

Answer 20

A hydraulic line fitting that seals the line when the fitting is diconnected. used on the lines connected to the enfine-driven hydraulic pump.

Question 21

What is the primary purpose of shuttle valves?

Answer 21

Connects the normal and emergency systems together.

Question 22

What is the purpose of pressure relief valves?

Answer 22

Protects the hydraulic system from excess pressure cause form thermal expansion, pressure surges, and the failure of a hydraulic pump’s compensator.

Question 23

What is the purpose of a hydraulic actuator?

Answer 23

To convert hydraulic fluid pressure into mechanical force, or action to perform work.

Question 24

What are the two types of double acting actuators?

Answer 24

Balanced and unbalanced

Question 25

What is an accumulator?

Answer 25

Allows an incompressible fluid to be stored under pressure by the force produced by a compressible gas.

Question 26

What are the two types of pressure gauges used on Coast Guard aircraft?**

Answer 26

Direct Reading and synchro-type