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Flashcards in Hydraulic And Pneumatic Deck (30):

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

Mineral base is red and phosphate-ester base is light purple


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

Materials will be damaged and softened, or the paint will peel


Name several sources used to develop hydraulic pressure

Hand , engine driven , 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, and 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

Limits the amount of pressure in the system


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

constant volume or variable volume


What's the difference between pneumatic systems and hydraulic

Pneumatic system is compressible and has no return system

Hydraulic system is incompressible


Describe the purpose of a pressure regulator

manages the output of the pump to maintain system pressure.


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


What safety precautions must be taken prior to disassembling an accumulator

Release all of the air or preload


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

Vegetable, mineral, and phosphate-esters


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

capped or plugged immediately after they are disconnected


What types of components or system are pneumatically operated in some aircraft

Landing gear, breaks, flaps, and other mechanical actuators


Name several sources of pneumatic power

Storage bottles, engine bleed air, engine driven compressor 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

controls the rate of flow


What are the reasons for periodically purging a pneumatic system

To remove moisture and contaminants


How do you determine which type of hydraulic fluid to use in a particular aircraft or system

Aircraft maintenance manual, place card attached to the reservoir


What will happen to the seals in a vegetable base hydraulic system of it is serviced with mineral base or phosphate ester base fluids

Swell, brake down, and block the system


What is the purpose of a unloading valve on a closed hydraulic system

Provides a low pressure path for fluid to flow from the pump back to the reservoir, also acts as a pressure regulator


What is the function of a wing overload valve

Prevents possible structural damage to the flaps or flap system


What happens to the air after a pneumatic system is operated

Is dumped overboard


What's the purpose of a accumulator

Prevent hydraulic system shock when under high load demand conditions


What is an example of a phosphate ester base fluid



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

Use only seals identified by the part number that is specified in the components maintenance Manuel


Whet type of system is used in a low- pressure pneumatic system

Vane type pump


What two filters are used in a pneumatic system

Micronic ( paper) and screen