A&p O&p Airframe Part 2 Hydraulic & Pneumatic Power Systems

Front 1

What kind of filter is a micronic filter?

Back 1

A filter with special paper element.

Front 2

What is a double-action pump?

Back 2

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

Front 3

Why do most engine driven hydraulic pumps have a shear section in the drive couplings?

Back 3

As a safety, should the pump seize the shear section will break disconnecting the pump from the engine and preventing further damage.

Front 4

What does an unloading valve do in a hydraulic system?

Back 4

Also known as a pressure regulator, it controls pressure by shifting the pumps outlet fluids from the pressurized system back into the reservoir when the system pressure is high enough and vice versa.

Front 5

What is the purpose of an accumulator in an aircraft hydraulic system?

Back 5

The accumulator holds the pressure on hydraulic fluid in the system.

Hint 5

The pressure is usually held by compressed air or nitrogen acting on the fluid through a bladder or diaphragm or piston type accumulator.

Front 6

What Is the purpose of an orifice check valve in an aircraft hydraulic system?

Back 6

Allows the full flow of fluid in one direction through the valve, but restricts the flow in the opposite direction.

Front 7

Where are line-disconnect fittings normally located in an aircraft hydraulic system?

Back 7

On engine driven pump to aircraft hydraulic systems.

Front 8

What is a single-action hydraulic actuating cylinder?

Back 8

A linear actuating cylinder that uses hydraulic fluid pressure to move the piston in only One direction, the Piston is returned by a Spring.

Front 9

What is a sintered metal hydraulic filter?

Back 9

Surface filter whose element is made of powdered metal fused under heat and pressure.

Front 10

What is the purpose of the differential pressure indicator on hydraulic filter?

Back 10

It indicates when the filter is clogged and fluid is bypassing the filter element.

Front 11

What is a Cuno filter?

Back 11

An edge filter made of a stack of thin metal disks separated by the scraper blades. Contaminants collect on the edge of the disks and are periodically scrapped out by rotating the disks. Contaminants collect in the bottom of the filter case for future removal.

Front 12

Is a Chevron seal a one-way or two-way seal?

Back 12

A one-way seal.

Front 13

To which side of a Chevron seal should the pressure be applied?

Back 13

To the open side.

Front 14

Is an o-ring seal a one-way or a two-way seal?

Back 14

A two-way seal.

Front 15

How can you be sure of getting an o-ring made of the correct material for a specific hydraulic component?

Back 15

It must have the correct part number from a reputable source.

Front 16

On which side of an o-ring should the backup ring be placed?

Back 16

The side away from the source of pressure.

Front 17

What should be done to the sharp edges of threads and actuator pistons when installing o-rings

Back 17

Sharp edges should be covered with paper.

Front 18

What are two basic differences between a hydraulic and a pneumatic system?

Back 18

Fluid in a hydraulic system is incompressible while in the pneumatic system it is compressible and a pneumatic system has no return system.

Front 19

What are two functions of a low-pressure pneumatic system in an aircraft?

Back 19

To operate the gyros and the flight instruments, and to operate the deicer in the pneumatic deicer boots.

Front 20

What type of pump is used in a low-pressure pneumatic system?

Back 20

Vane-type pump

Front 21

Why do high-altitude aircrafts that have pneumatic gyro instruments use pressure actuated instruments rather than vacuum actuated instruments?

Back 21

At high altitude there is not enough air mass to drive the gyros at their required speed.

Front 22

What effect would a dirty inline air filter have on the operation of pneumatic gyro instruments?

Back 22

The instruments will not get enough air to spin up to their required speed.

Front 23

Of what material are the vanes in the dry type air pump made?

Back 23

Carbon

Front 24

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

Back 24

A variable orifice.

Front 25

What is the purpose of moisture separator in a high-pressure pneumatic system?

Back 25

A moisture separator removes about 98% of the moisture in the air. Collects moisture from the air and holds it onto the baffles until the system is shut down.

Hint 25

When inlet pressure to the moisture separator drops below 450 PSI, a drain valve opens and all of the accumulated moisture is discharged overboard.

Front 26

What are two types of filters that are used in an aircraft pneumatic system?

Back 26

Micronic (paper) type or screen type.

Front 27

What are two basic types of hydraulic fluid used in a modern aircraft?

Back 27

Mineral base fluid and phosphate ester base fluid.

Front 28

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

Back 28

From the standpipe

Hint 28

The emergency pump takes its fluid from the bottom of the reservoir. The system is designed as such so if the system fails and all the fluid is overboard there still will be enough fluid in the reservoir to allow the emergency system to extend the landing gear and actuate the brakes.

Front 29

Why are some hydraulic reservoirs pressurized?

Back 29

Pressurization ensures the fluid will be supplied to the inlet of the pump at high altitude when there is not enough atmospheric pressure to do so.

Front 30

What are two ways aircraft hydraulic reservoirs may be pressurized?

Back 30

By an aspirator in the fluid return line or by bleed air from one of the engine compressors.

Front 31

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

Back 31

Trichloethylene or the solvent recommended by the aircraft manufacturer.

Front 32

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

Back 32

Naphtha, Varsol, or stoddard solvent.

Front 33

Where can you find the type of hydraulic fluid required for a particular aircraft?

Back 33

In the maintenance manual for the aircraft, it's also on the placard on the system reservoir.

Front 34

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

Back 34

Soap and water.

Front 35

How can you be sure that the replacement seal in a hydraulic component is compatible with the fluid used in the system?

Back 35

Use only the seal identified by the part number as specified in the component maintenance manual.

Front 36

What must be done to the lines that are disconnected when replacing an aircraft hydraulic system component?

Back 36

They must be capped with the correct fluid cap or plug, masking tapes or other types of adhesive tapes should never be used.

Front 37

What must be done before a pressurized reservoir is serviced?

Back 37

All of the pressure must be bled off.