11.11 Flashcards
What psi do large aircraft hydraulics work up to
5000 pai
What psi do large aircraft hydraulics work up to
5000 psi
What advantages are there of hydraulics
They are easy to control and give accurate results.
It is easy to check if there is any leakage in the system.
It has automatic lubrication systems and protects from corrosion.
The hydraulic system does not cause sparks and is safe on flights.
It is easy to repair and maintain.
What disadvantages is hydraulics
Using inappropriate fluids damages the components of the hydraulic system.
Leakage of fluids can cause ignition of fire hazards.
Contamination in the system or fluids affects the performance and even damages the system.
What’s 1 bar in psi
14.5
What psi do civil aircraft hydraulic systems work with
3000 psi
What’s hydrostatic and hydrodynamic pressure what ones used in ac
Hydro static - pressure produced by static or nearly static fluids (this is the type used in ac)
Dynamic- pressure caused by movin liquids
What’s hydrostatic and hydrodynamic pressure what ones used in ac
Hydro static - pressure produced by static or nearly static fluids (this is the type used in ac)
Dynamic- pressure caused by movin liquids
What’s in place for hydraulic redundancy
3 systems
What’s on open centre hydraulic system
One that had fluid flow but no pressure in the system when the actuating members are idle
What’s the difference between the selector valve in the open centre hydraulics system ans the closed centre system
Always connected in a series in open centre systems
What does every hydraulic system need
A mechanical or electric system
What’s the fluid doing in the closed centre hydraulic system
Fluids under pressure whenever pumps operating
What’s the fluid doing in the closed centre hydraulic system
Fluids under pressure whenever pumps operating
What controls the pressure of a closed centre system with a variable displacement pump
Pumps integral pressure mechanism compensator
What regulates the pressure and what acts as a back up device in a closed centre hydraulic system with a constant delivery pump
Pressure regulator
Relief valve
What’s an advantage of the open centre hydraulic system over the closed centre hydraulic system
The continuous pressurisation of the system is eliminated
What does the gradual build up of pressure of the open centre system provide
Smooth actuation of surface but this means it takes a lot longer to move that then the closed system
Are closed or open centre systems more commonly used
Closed due to speed of actuation
What’s a benifit of power boost systems
Reduce weight by eliminating hydraulic lines and quantities of the fluid
What type of characteristics do ac oils need to have
Low flammability
Corrosion resistance
Good lubricating quality
Resistance to freezing
Non-evaporating
Non-foaming
Chemical stability (the ability of the oil to resist oxidation and deterioration for prolonged periods, this reduces the need for frequent oil changes)
Hygroscopic quality
What happens to viscosity as temp decreases
Increases
What’s chemical stability
Liquids resistance to oxidation and deterioration over long periods
What’s a flash point
The point in which a liquid gives off another vapour in sufficient quantity to ignite momentarily or flash when a flames applies