Chapter 8 - Hydraulic and Pneumatic Power Systems - Oral Questions Flashcards Preview

A&P Technician AIRFRAME > Chapter 8 - Hydraulic and Pneumatic Power Systems - Oral Questions > Flashcards

Flashcards in Chapter 8 - Hydraulic and Pneumatic Power Systems - Oral Questions Deck (20):

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

Vegetable (MIL-H-7644 Blue Vegetable Base)

Mineral (MIL-H-5606 Red Kerosene/Petroleum Base)

Phosphate-esters (Skydrol Purple Phosphate-ester Base)


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

Mineral based fluids are red

Phosphate-ester based fluids are light purple


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

The materials will be damaged and/or softened, or the paint will peel


Name several sources used to develop hydraulic pressure.

Hand pumps, engine- driven pumps, and electrically driven pumps


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

A clogged filter element


Describe several methods of pressurizing a hydraulic reservoir.

Engine bleed air,

system pressure acting on a small piston in the reservoir,

using variable-displacement hydraulic pumps


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

A shear section in the pump driveshaft will break, disconnecting the pump from the engine


Describe the purpose of a pressure relief valve.

Pressure relief valves limit the maximum pressure produced by the pump, thereby preventing failures of the system components


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

As a constant volume or a variable volume


Describe the operation of a gear-type pump.

Two meshed gears, driven by a power source, rotate in a housing. Inlet fluid is carried around the outside of the gears and delivered to the outlet side as the gears rotate

A image thumb

Describe the purpose of the pressure regulator.

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

A image thumb

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

An accumulator


What are the three different types of accumulators?

Piston, diaphragm, and bladder

A image thumb

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

Release all of the air or preload


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

All lines should be capped or plugged immediately after they are disconnected


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

Landing gear,


flaps, and

other mechanical actuators


Name several sources of pneumatic power

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


What happens to excess pressure in a pneumatic system?

A relief valve vents it overboard


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

To control the rate of flow of the airflow


What are the reasons for periodically purging a pneumatic system?

To remove moisture and contaminants