Hydraulic Principles Flashcards
How is pressure generated in a hydraulic system?
Resistance to flow.
True or false: oil is incompressible?
True.
A passive hydraulic system is a system that requires human power to raise blank.
A system that requires human power to raise tempurature.
How many pumps does an active hydraulic system have?
One or more.
What type of centred system uses pressure only when demanded?
Open centred.
What type of oil container - should you replenish an aircraft with?
Unopened.
What viscosity do we want hydraulic fluid to have?
Low viscosity.
What colour is mineral hydraulic fluid?
Red.
If there is a purple puddle under . Your aircraft what is it?
Hydraulic fluid.
What is a bonus of hydraulic systems in regards to energy?
Very little energy lost in the processes.
Is hydraulic fluid corrosive?
Yes, very.
What is the range of hydraulic pressure in modern aircraft?
3000 → 4000 psi.
What should you do to the power transfer value if there is a lease in one of the hydraulic systems.
Close it.
What type of valve uses a ball and spring? (NV valve)
Non return valve
During the aircraft walk around what level would you expect to see the hydraulic resouvior at??
Almost full
Why is the hydraulic resouiour under high pressure?
To reduce evaporation.
What property does nitrogen gas have that means it is used in a hydraulic accumulator?
It is inert.
When are accumulators used for hydraulic pressure? To do with the pumps.
If the pump fails.
What type of delivery pump goes hand in hand with the automatic cut out value?
Constant delivery pump
True or false : In constant pressure pumps, the pump output is dependant on speed.
False.
On start up of an engine, the pump swash playe is at what degree?
Zero.
How many microns is the size of debris a hydraulic filter can stop?
5 microns.
What valve allows for the most appropriate supply to be used in hydraulics?
Shuttle valve.
Hydraulic fuses close when there is a pressure blank.
When there is a pressure differential?
What does the blue system control on an airbus?
Flight controls.
Which colour reservoir has a stack pipe in an airbus?
Yellow.
What is a ram air turbine?
Emergency generator.
High pressure blank air powers a turbine which powers a hydraulic pump (this is used on older aircraft)
Bleed.
What is the pressure differential when the PTU activated in the 320?
500psi.
A hydraulic accumulator serves to blank the hydraulic pressure fluctuations and act as a blank resorviour.
Dampen - backup.
During a normal aircraft service, an engineer notices an oily mist leaving the pressure release valve whilst draining the nitrogen from a horizontally mounted hydraulic accumulator. What does this indicate?
Theres a leak.
A possible pneumatic source in a single engine piston aircraft is…
Compressor
A FADEC piston engine has two _____ to achieve redundancy.
Power supplies
An aircraft is equipped with two individual hydraulic systems. One of the systems has a pump failure. How will the system alert the pilot?
A master caution and an amber light.
To prevent vapour locking, which can lead to fuel starvation, a common type of limitation imposed by the Minimum Equipment List (MEL) in large transport aeroplanes for complete boost pump failure is…
Max limiting altitude.
Which one of the following liquids are considered highly corrosive?
(1) Anti-icing fluid
(2) De-icing fluid
(3) Window washer
(4) Hydraulic fluid
(5) Engine oil
(6) Jet fuel
4
What is the component that converts hydraulic pressure into linear motion? (Pressure regulator / jack / hydraulic pump / accumulator)
Jack
What is cavitation?
Air bubbles
A constant delivery hydraulic pump provides (1) _____ and (2) _____.
(Constant/varying pressure - constant/varying volume)
Varying P - constant V
The hydraulic device, which functionality is comparable to a diode in an electrical circuit, is a… blank valve
Check
What becomes damaged if a mineral based hydraulic oil is used in in a system designed for synthetic hydraulic oil?
Seal
