Hydraulic And Pneumatic Flashcards
(30 cards)
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
