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Aircraft System > Aircraft system hydraulic system > Flashcards

Aircraft system hydraulic system Flashcards

1
Q

The ________in aircraft provide a means for the operation of aircraft components. The
operation of landing gear, flaps, flight control surfaces, and brakes is largely accomplished.

A

hydraulic system

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2
Q

Hydraulic system complexity varies from _____ aircraft that
require fluid only for manual operation of the wheel brakes to______ transport aircraft
where the systems are large and complex.

A

small;large

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3
Q

To achieve the necessary redundancy and
reliability, the system may consist of several subsystems. Each subsystem has a power
generating device (pump), reservoir, accumulator, heat exchanger, filtering system, etc.

A

hydraulic system

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4
Q

It states that pressure applied to any part of a confined liquid is
transmitted with undiminished intensity to every other part. Thus, if a
number of passages exist in a system, pressure can be distributed through all
of them by means of the liquid.

A

Pascal law

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5
Q

USERS OF HYDRAULICS IN A CESSNA AIRCRAFT

A

braking system,

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6
Q

USERS OF HYDRAULIC SYSTEM IN AIRBUS AIRCRAFT

A

flight controls, landing gear, brakes and nose wheel steering, cargo doors, thrust reverser, ram air turbine

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7
Q

ADVANTAGES OF USING HYDRAULICS

A

• Lightweight
• Ease of Installation
• Simplification of Inspection
• Minimum Maintenance Requirements
• Incompressible, and this fact enables movement to be transmitted through pipelines, over great
distances, without loss of time or motion.
• They provide good lubrication of components.
• Their viscosity is low enough to minimize friction in pipelines and to allow high-speed operation
of motors and pumps, but high enough to prevent leakage from components.
• They prevent internal corrosion in the system.
• They have a wide operating-temperature range.

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8
Q

used primarily to transmit and distribute forces
to various units to be actuated. Liquids are able to do this because they are
almost incompressible.

A

hydraulic fluid

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9
Q

IMPORTANT PROPERTIES OF A HYDRAULIC FLUID THAT IS USED IN AVIATION

A

viscosity, chemical stability, flash point, fire point

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10
Q

is the temperature at which a substance gives off vapor in sufficient
quantity to ignite and continue to burn when exposed to a spark or flame., a high ____ is required of desirable hydraulic liquids.

A

fire point

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11
Q

is the temperature at which a liquid gives off vapor in sufficient
quantity to ignite momentarily or flash when a flame is applied. It is desirable for hydraulic liquids because it indicates good resistance to combustion and a low degree of evaporation at normal temperatures.

A

flash point

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12
Q

It is another property that is exceedingly important in selecting a hydraulic
liquid. It is the liquid’s ability to resist oxidation and deterioration for long periods.

A

chemical stability

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13
Q

One of the most important properties of any hydraulic fluid. It is an internal resistance to flow. A liquid such as gasoline that has a low viscosity flows easily,
while a liquid such as tar that has a high viscosity flows slowly. Viscosity increases as
temperature decreases. A satisfactory liquid for a given hydraulic system must have enough body to give a good seal at pumps, valves, and pistons, but it must not be so thick that it offers resistance to flow, leading to power loss and higher operating temperatures. These factors add to the load and to excessive wear of parts. A fluid that is too thin also leads to rapid wear of moving parts or of parts that have heavy

A

viscosity

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14
Q

The instruments used to

measure the viscosity of a liquid is known as

A

viscometers or viscosimeters.

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15
Q

TYPES OF HYDRAULIC FLUIDS USED IN AVIATION

A

MINERAL-BASED FLUIDS, POLYALPHAOLEFIN-BASED FLUID, PHOSPHATE ESTER-BASED FLUID

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16
Q

is processed from petroleum. It has an odor

similar to penetrating oil and is dyed red.

A

mineral based fluids or MIL-H-5606

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17
Q
  • good low temperature fluidity. (-65°F to 274°F)
  • robust wear protection, oxidation and corrosion resistance
  • high degree of flammability
A

mineral based fluids or MIL-H-5606

18
Q

MIL-H-83282 is a fire-resistant hydrogenated _______ based fluid developed in the 1960s to overcome the flammability characteristics of MIL-H-5606.

A

polyalphaolefin or MIL-H- 83282

19
Q

Fire Resistant
• Self-extinguishes when the flame/heat source is removed and has excellent flame propagation
inhibition properties.
• Corrosion Resistant
• Operating temperature limit is -40oF to 401oF

A

polyalphaolefin based fluid or MIL-H- 83282

20
Q

These fluids are used in most commercial transport category aircraft and are extremely
fire-resistant. However, they are not fireproof and under certain conditions, they burn. In
addition, these fluids are very susceptible to contamination from water in the atmosphere.
Progressive development of these fluids occurred as a result of performance requirements
of newer aircraft designs. The airframe manufacturers dubbed these new generations of
hydraulic fluid, such as Skydrol® and Hyjet®, as types based on their performance.

A

PHOSPHATE ESTER-BASED FLUID

21
Q

CHARACTERISTICS OF A PHOSPHATE ESTER BASED
HYDRAULIC FLUID LIKE MODERN SKYDROL
VERSION V AND HYJETVERSION V

A
  • Improved flammability characteristics
  • Low density
  • Excellent corrosion protection
  • Excellent low and high temperature viscosity balance
  • Improved protection against electro-chemical corrosion
22
Q

HYDRAULIC SYSTEM COMPONENTS

A 
HYDRAULIC RESERVIOR
HYDRAULIC PUMP
HYDRAULIC FILTERS
CHECK VALVE
 SHUTOFF VALVES
PRESSURE RELIEF VALVE
PRESSURE REGULATOR
SELECTOR VALVE
HYDRAULIC ACTUATOR
ACCUMULATOR
23
Q

is a steel sphere divided into two chambers by a synthetic
rubber diaphragm. The upper chamber contains fluid at system pressure, while
the lower chamber is charged with nitrogen or air.

A

accumulator

24
Q

FUNCTIONS OF ACCUMULATOR

A

• Dampen pressure surges in the hydraulic system caused by actuation of a unit
and the effort of the pump to maintain pressure at a preset level.
• Aid or supplement the power pump when several units are operating at once
by supplying extra power from its accumulated, or stored, power
• Store power for the limited operation of a hydraulic unit when the pump is
not operating.
• Supply fluid under pressure to compensate for small internal or external (not
desired) leaks that would cause the system to cycle continuously by action of
the pressure switches continually kicking in.

25
Q

It converts hydraulic power to mechanical action. This is
connected to hydraulic system users and actuates the hydraulic
system users.

A

hydraulic actuator

26
Q

This valve allows the changing of direction of the flow of
pressurized hydraulic fluid. This is done by rotation of the
integrated assembly of the valve.

A

selector valve

27
Q

This is used in a Hydraulic System that is driven by engine driven pumps
(referring to the modern commercial airliners).
• One of its purpose is to manage the output of the pump
to maintain system operating.
• The other purpose is to permit the pump to turn without resistance (termed
unloading the pump) at times when pressure in the system is within normal
operating range.

A

pressure regulator

28
Q

This is used in a Hydraulic System that is driven by engine driven pumps
(referring to the modern commercial airliners).
• One purpose of the pressure regulator is to manage the output of the pump
to maintain system operating.
• The other purpose is to permit the pump to turn without resistance (termed
unloading the pump) at times when pressure in the system is within normal
operating range.

A

pressure regulator

29
Q

Pressure relief valves cannot be used as pressure regulators in large hydraulic
systems that depend on engine-driven pumps for the primary source of
pressure because the pump is constantly under load and the energy expended
in holding the pressure relief valve off its seat is changed into heat. This heat is
transferred to the fluid and, in turn, to the packing rings, causing them to
deteriorate rapidly.

A

NOTE

30
Q

Hydraulic pressure must be regulated in order to use it to perform the desired
tasks. It is used to limit the amount of pressure being
exerted on a confined liquid. This is necessary to prevent failure of components
or rupture of hydraulic lines under excessive pressures.

A

PRESSURE RELIEF VALVE

31
Q

are used to shut off the flow of fluid to a particular system or
component. In general, these types of valves are electrically powered. are also used to create a priority in a hydraulic system and are controlled
by pressure switches.
• In case of emergency (leaks, fire, pumps malfunction) these valves are used
to cutoff the flow of hydraulic fluid.

A

shut off valves

32
Q

allows the flow of fluid in one direction only.

It prevents the backflow of hydraulic fluid.

A

check valve

33
Q

designed to prevent the passage of solids greater than 10

microns (0.0003 94 inch) in size

A

micron element

34
Q

is a screening or straining device used to clean the hydraulic fluid,
preventing foreign particles and contaminating substances from remaining in
the system.
• It may be located within the reservoir, in the pressure line, in the return
line, or in any other location the designer of the system decides that they are
needed to safeguard the hydraulic system against impurities.

A

hydraulic filter

35
Q

This device is responsible in delivering hydraulic power into the
users of hydraulic system.
• Hydraulic power output 3000 psi.

A

hydraulic pump

36
Q

is a tank in which supply of hydraulic fluid for the system is
stored.
• It furnishes a place for the fluid to purge itself of air bubbles
that may enter the system. Foreign matter picked up in the system may also
be separated from the fluid in the reservoir or as it flows through line filters.

A

HYDRAULIC RESERVIOR

37
Q

Hydraulic Fluids like Phosphate esters are good solvents and
dissolve away some of the fatty materials of the skin. Repeated or
prolonged exposure may cause drying of the skin, which if
unattended, could result in complications, such as dermatitis or
even secondary infection from bacteria. Phosphate ester-based
fluids could cause itching of the skin but have not been known to
cause allergic-type skin rashes.

A

HEALTH AND HANDLING IN WORKING ON

HYDRAULICS

38
Q

aircraft maintenance safety

A

COVERALLS, NITRILE GLOVES AND POLYMERIC GLOVES,SAFETY GOGGLES

39
Q

ATA 29 - HYDRAULIC POWER
(AIRBUS)
The Aircraft has three independent hydraulic systems:

A

green, yellow, blue,

40
Q

The three hydraulic system supply hydraulic power at

3000 psi to the users:

A
  • Flight controls
  • Landing gear
  • Brakes
  • Nose wheel steering
  • Cargo doors
  • Thrust reverser operation
41
Q

Hydraulic fluid cannot be transferred from transferred from one system to another.
- A reservoir in each hydraulic system is pressurized with air to prevent cavitation.
- A power transfer unit enables the green system to be pressurized by the yellow
system and vice versa.
- Fire shutoff valves are located between the reservoirs and EDPs. They isolate the system
incase of fire.

A

Hydraulic fluid cannot be transferred from transferred from one system to another.
- A reservoir in each hydraulic system is pressurized with air to prevent cavitation.
- A power transfer unit enables the green system to be pressurized by the yellow
system and vice versa.
- Fire shutoff valves are located between the reservoirs and EDPs. They isolate the system
incase of fire.

Aircraft System (11 decks)

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