Jeppesen Oral- Chapter 8 (Hydraulic, Pneumatic Power Systems)

Question 1

What materials form the bases of the three types of hydraulic fluids?”

Answer 1

Vegetable, mineral, phosphate esters

Question 2

What colors denote mineral based and phosphate ester based hydraulic fluids?

Answer 2

Mineral based are red, phosphate esters are purple

Question 3

What are the results of exposing lacquers, oil-based paint, plastic resins, and vinyl compounds to phosphate ester based hydraulic fluid?

Answer 3

Materials will be damaged and softened and the paint will peel

Question 4

Name several sources used to develop hydraulic pressure?

Answer 4

Hand pumps, engine driven pumps, and electrically driven pumps

Question 5

What would cause the bypass valve in a hydraulic filter to open and allow unfiltered fluid to circulate in the system?

Answer 5

A clogged filter element

Question 6

Describe several methods of pressurizing a hydraulic reservoir?

Answer 6

Engine bleed air, variable displacement hydraulic pumps

Question 7

What feature prevents engine damage if an engine driven hydraulic pump seizes or is overloaded?

Answer 7

A shear section in the pump driveshaft will break

Question 8

Describe the purpose of a pressure relief valve

Answer 8

Limits maximum pressure produced by the pump

Question 9

Engine driven pumps deliver the output fluid flow in what two forms?

Answer 9

As a constant volume or a variable volume

Question 10

Describe the operation of a gear pump

Answer 10

Two meshed gears , rotate in a housing. Inlet fluid carried around the outside of the gears and delivered to the outlet side

Question 11

Describe the purpose of a pressure regulator.

Answer 11

Manage output of the pump to maintain system pressure. They allow the pump to be unloaded so it turns without significant resistance

Question 12

What is the device that is used in some systems, to supplement the pump output during periods of high demand?

Answer 12

An accumulator

Question 13

What are the three different types of accumulators?

Answer 13

Piston, diaphragm, and bladder

Question 14

What safety precautions must be taken prior to disassembling an accumulator?

Answer 14

Release all the air pr preload

Question 15

When a hydraulic unit is replaced, what precautions should be taken to avoid contamination of the system?

Answer 15

All lines should be capped after they are disconnected

Question 16

What types of components or systems are pneumatically operated in some aircraft?

Answer 16

Landing gear, brakes, flaps

Question 17

Name several sources of pneumatic power

Answer 17

Storage bottles, engine bleed air, engine driven compressors or vane type pumps

Question 18

What happens to excessive pressure in a pneumatic system?

Answer 18

A relief valve vents it overboard

Question 19

What is the function of a restrictor in a pneumatic system?

Answer 19

To control the rate of flow of the JSAT

Question 20

What are the reasons for periodically purging a pneumatic system?

Answer 20

To remove moisture and contaminants

Question 21

What kind of filter is a micronic filter?

Answer 21

A filter with a special paper element

Question 22

Does the main hydraulic pump take its fluid from the bottom of the reservoir or from the standpipe?

Answer 22

The main pump normally takes its fluid from the standpipe, while the emergency pump takes its fluid from the bottom of the reservoir. If a break in the system should allow the main mump to pump all its fluid overboard, there will still be enough fluid in the reservoir to allow the emergency system to extend the landing gear and actuate the brakes

Question 23

Why are some hydraulic reservoirs pressurized?

Answer 23

Pressurization assures that fluid will be supplied to the inlet of the pumps at high altitude when there is not enough atmospheric pressure to do this.

Question 24

What is a double-action pump?

Answer 24

A pump that delivers fluid with the movement of the pump handle in both directions.

Question 25

What does an unloading valve do in a hydraulic system?

Answer 25

The unloading valve, or pressure regulator, controls system pressure by shifting the pump outlet fluid from the pressurized system back into the reservoir when the system pressure is high enough. The fluid circulates with very little load on the pump until the system pressure drops to the regulator kick-in value. The pump then forces fluid into the system until the pressure builds back up to the regulator kick-out value

Question 26

What kind of device is used to control the speed of movement of the piston in a pneumatic actuator?

Answer 26

variable orifice

Question 27

Why do most high-pressure pneumatic systems include a moisture separator?

Answer 27

When the pressure of the stored air is reduced to the value that is needed in the system, the temperature drops enough to freeze any water that is in the air. The moisture separators remove this water before it can freeze and block the system.

Question 28

What is used to flush a hydraulic system that uses Skydrol hydraulic fluid?

Answer 28

Trichlorethylene

Question 29

What is used to flush a hydraulic system that uses mineral base hydraulic fluid?

Answer 29

Naphtha, varsol, or Stoddard solvent

Question 30

What is used to remove phosphate-ester-base hydraulic fluid from aircraft tires?

Answer 30

Soap and water

Question 31

Why do some hydraulic pressure gages have a snubber installed between them and they hydraulic pump?

Answer 31

The snubber keeps the gage from fluctuating.