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Hydraulics and landing gear

Which of the following is NOT an advantage of using hydraulic systems on an aircraft?

Greater number of mechanical components

Light weight

Ease of Installation

To what percent are hydraulic systems efficient?

80%

95%

100%

Which law states that, "pressure applied to any part of a confined liquid is transmitted with undiminished intensity to every other part?

Pascals Law

Bernoullis Principle

Newtons third law

Viscosity is defined as?

The mass by volume of a liquid

A fluids internal resistance to flow

The specific gravity of the liquid

What can happen when hydraulic fluid continuously passes through a system hot spot?

The fluid will become contaminated with abrasive particulates

The fluid may ignite and cause a failure in the system

The fluid may carbonize or sludge

What relationship exists between a liquids viscosity and its resistance to heat?

Liquids with a high viscosity have a greater resistance to heat

Liquids with a high viscosity have a reduced resistance to heat

There is no measurable relationship between heat resistance and viscosity

By comparison to the other types of hydraulic fluid discussed, how flammable is MIL-H-5606?

Least Flammable

More flammable than Mil-H-83282, but less flammable than Skydrol

Most flammable

Of what base is skydrol?

Mineral Oil

Phosphate Ester

Polyalphaolefin

How do open center hydraulic systems operate?

Positive displacement pumps and not variable displacement pumps

Idles at full pressure. The relief valve ensure pressure is constant while the users are in operation.

Fluid constantly flows, but no pressure in the system when the actuating mechanisms are idle.

In a closed hydraulic system, the selector valves are installed in?

Paralllel

Series

Either one. The orientation is unimportant

Which is true concerning aircraft that utilize non-pressurized hydraulic reservoirs?

These aircraft fly at lower altitudes and perform advanced aerobatic maneuvers

These aircraft fly at higher altitudes

These aircraft fly at lower altitudes and do not execute extreme maneuvers

Which of the following is NOT a source used to pressurize hydraulic reservoirs

Ram air

Bleed air

Hydraulic

Before servicing a hydraulic system on an aircraft, what should be ensured?

Fluid must be at ambient temperature

Must be in standard configuration

All spoilers are deployed and all flight control surfaces are moved to their max extent

A hydraulic reservoir that has been properly serviced will be?

Full

Partially Filled

Nearly Empty

Typically, micronic filters are

Paper, disposable/non-cleanable

Paper, cleanable

Metal Screen, disposable

What is the purpose of the thermal lockout device in the hydraulic filter differential pressure indicator

Prevents hydraulic fluid from flowing to the pump in the event of extreme overheat

Allows filter to be bypassed when fluid temps are low

Prevents DPI from deploying the flag when temps are low and viscosity is high

Which type of hand pump is NOT used in aviation?

Single action hand pump

Double action hand pump

Rotary hand pump

Which type of powered hydraulic pump is most commonly used in modern aircraft?

Positive displacement

Variable displacement

Vane Type

In a variable displacement hydraulic pump, during normal operation, what factor effects the output volume of the pump

Engine RPM

Pump inlet pressure

Pump outlet pressure

In a hydraulic system, where is the system fluid temperature transducer usually installed?

Reservoir

Pressure Manifold

At the outlet of the pump

A biased ply tire has its angle of the plies arranged in such a fashion that the tire becomes flexible...?

In the sidewall area of the tire

Perpendicular to the sidewall and the direction of rotation

In the bead of the tire area

The designed deflection of an aircraft tire is how many times greater that an automotive tire?

Which of the following is NOT a function of the grooves designed into the tread of an aircraft tire?

To absorb side loads during heavy breaking

To channel water

To assist in cooling of the tire

A tire chine is used to

Anchor the carcass plies to the bead of the tire

Protect the sidewall of the tire from damage due to operation on the unpaved landing surfaces

Deflect water away from in inlet of fuselage mounted engines

When can accurate tire pressures be checked and verified?

When on weight on wheels

Either on or off the aircraft

When the tire is unloaded

What is the cause of Chevron cuts on a tires tread?

Operation of unpaved runway. Remove from service

Operation of grooved landing surface. Acceptable as long as they do not cause chunking of the tread

Operation of a grooved landing surface and cause for tire to be deemed unserviceable

The primary purpose pf the tire bead is to

Tightly hold the tire to the wheel, ensuring an airtight fit and preventing wheel slippage

Transfer impact loads from the tread to the sidewall

Provide an anchor point for the carcass plies

Is it permissible to store aircraft tires in the horizontal orientation?

Yes, Indefinitely

Yes, but for no longer than 6 months

How can you determine the shelf life of an aircraft tire tube?

No mandatory shelf life

5 years

Indicated on the packaging and designated by the manufacturer

What is the purpose of tire talc?

To lubricate the tire bead to aid in the wheel mounting process

To ensure easy mounting and free movement between the tube and tire a they inflate

Its used to prevent ozone from damaging tires left in long term storage

What is the purpose of a shuttle valve

To delay the actuation of a hydraulic system from an alternate or emergency system

To isolate the normal hydraulic system from an alternate or emergency system

To transfer hydraulic fluid from one hydraulic system to another

Which of the following is NOT a function of the hydraulic accumulator

Transfer power from an adjacent system in the event of pump failure

Provide a cushioning effect for large demands placed on the pump

Provide an additional source of fluid under pressure for emergency operation

Hydraulic accumulators are typically charged with

Shop air

Oxygen

Nitrogen

What returns the piston of a single acting actuator once hydraulic pressure is removed

Hydraulic fluid, under pressure, being ported to the retract side of the actuator

A spring

A negative pressure that is created, by the hydraulic pumps, on the extend side of the actuator

Which of the following is NOT a function of a hydraulic shutoff valve?

To shut off the flow of a hydraulic fluid to and engine driven pump in the event of an engine fire

To create the hydraulic lock in a flight control actuator to provide for gust lock protection

To stop the flow of fluid to an engine driven pump in the event of a hydraulic system overheat

What component of a shutoff valve is most likely to fail?

The physical shutoff component

The electric actuating motor

Either, they are fixed together and must be replaced as one single unit

What should be done prior to disassembling a hydraulic accumulator?

Must be cycled to prevent trapped fluid

The hydraulic pump on the aircraft should be cycled to ensure the accumulator is free of air

The gas charge should be relieved from the system

In a single acting actuator, two ports exist; one supplies fluid under pressure to the fluid side of the actuator. What is the purpose of the other port.

Where hydraulic pressure is applied

To vent the spring controlled chamber of the actuator of air

As an inspection point

What type of actuator uses hydraulic fluid to power it to both the extend and retract positions?

Single acting actuator

Double acting actuator

Hydraulically balanced actuator

A rotory actuator can also be called what?

A rack and pinion actuator

A hydraulic motor

A non-linear actuator

Of the following, which aircraft systems are not operated by a high pressure pneumatic system?

Wheel brakes

Flap actuation systems

Thrust reversers

High pressure pneumatic systems operate at pressures ranging from

500-1000 psi

1000-3000 psi

3000-5000 psi

What is the main disadvantage to pneumatic systems that use a high pressure bottle?

The high heat generated by the system

As an incompressible fluid, the gas in the system imparts too much mechanical shock upon the system and its compnents

Operation is limited by the small supply of bottled air

What is the purpose of a restrictor installed in a high pressure pneumatic system

To reduce the pressure downstream of the restrictor

To reduce the speed of actuation of the pneumatic components, downstream of the restrictor

The limit the flow of fluid in only one of two directions

In a pneumatic system, where is the moisture separator always installed?

Downstream of the compressor

Upstream of the compressor

Between the storage bottle and the compressor

How can you know that a chemical drier is serviceable?

When serviceable the cartridge should be blue in color

When serviceable the cartridge should be red in color

When serviceable the cartridge should be green in color

At what pressures do medium pressure pneumatic systems operate?

1000-3000 psi

500-1000 psi

50-150 psi

What is the most common source of pneumatic power for a medium pressure system?

Vane type compressor pump

A pressurized storage bottle

The engine bleed air system

Which of the following systems are operated by a medium pressure pneumatic system?

Wheel brakes

Engine starting

Opening and closing doors

Which of the following systems are operated by a low pressure pneumatic system?

Air conditioning and pressurization

Instruments

Wing and cowl anti-icing

For what reason are a single piece aircraft wheels NO LONGER used on modern aircraft?

Do not provide an adequate structure to contain the high pressures of modern aircraft tires

The strength and robustness of modern aircraft tires makes it impossible to install them on to single piece wheels.

Single piece wheels are unable to sufficiently disburse heat during heavy breaking.

What is the purpose of a thermal plug on aircraft wheels?

To prevent the wheel and tire from bursting due to excessively high temperatures

To prevent an assembly from damage due to erroneous over-inflation

To fuse minor air leaks in the wheel

What is the purpose of the over-inflation safety plug

To prevent the wheel and tire from bursting due to excessively high temps

To prevent an assembly from damage due to erroneous over-inflation

To fuse minor leaks in the wheel

Other than protecting the bearing cavity from FOD, what additional purpose may a hub cap be designed to facilitate?

Hydraulic fluid, under pressure, being ported to the retract side of the actuator

It provides a redundant means to hold the wheel onto the axle in the event that the axle nut becomes unserviceable

The hub cap engages the wheel speed transducer to provide electronic wheel speed data

What is the effect upon a component that experiences galling?

Metal welds and surface metal is destroyed as the motion continues and pulls the metal apart in the direction of motion

Tiny particles contaminate the bearing surface and produce a less than smooth surface

Corrosion occurs as a result of water penetrating the protective coating of the metal part

What is the best method for inspecting for cracks in aluminum aircraft wheels?

Die penetrant inspection

Visual Inspecion

Eddy current inspection

In a single disk brake system, from where does the energy to apply the brakes come?

From the aircraft hydraulic system, regulated by the input from the pilot's rudder pedals

From the pilot and combined with hydraulic pressure from the aircraft hydraulic system

From the pilot, transitted through a closed hydraulic system

What is the purpose of the keyways in the rotor disks if a multiple disk brake?

To engage and be rotated by the wheel

To provide a mounting point for the brake caliper

To allow the alignment of the brake caliper and rotor disks

What is the benefit of using segmented disk brakes in a multi-disk break vs standard disks?

Superior cooling characteristics

Increased strength and cooling characteristics

Segmented rotors provide ease in maintenance because they can be installed without removing the aircraft wheel tire assembly

In a floating disk brake, what component adjusts for brake lining wear during operation?

The return spring

The adjusting pin grip

The pressure plate lining puck

An independent brake system differs from the other types because?

It is the only system that does not utilize hydraulic fluid under pressure from the aircraft hydraulic system

It is the only system that uses hydraulic fluid under pressure from the aircraft hydraulic system

It is the only system that uses no hydraulics to operate; only pilot strength through push pull rods

If an airplane has no nosewheel steering system, what allows the aircraft to maneuver on the ground?

The aircraft turns by taxiing at a rapid pace and using the rudder to cause angular deflection

These aircraft utilize rigid landing gear systems and must be towed to and from the runway

Differential braking

What is the purpose of the compensating port in a master cylinder actuator?

It allows the fluid to expand safely without causing extension of the actuator

It account for operation during cold temperatures when the fluid is highly viscous

It provides a return path for the anti-skid system

In a boosted brake system, when does the airframe hydraulic system pressure act upon the brake units?

Any time the pilot presses the brake pedals. The brakes are entirely operated by the airframe hydraulic system which is only regulated by the varying application of the brake pedals, by the pilot.

Only during heavy braking

A boosted brake system does not use airframe hydraulic system pressure to operate

In power brake system, what regulates the fluid pressure sent to the brake units (excluding ant-skid operations)?

Actuation of the brake master cylinder, based on pilot input

The brake control valve in response to pilot input on the rudder pedals

Corrosion occurs as a result of water penetrating the protective coating of the metal part

In power brake systems what provisions help to supply the pilots with the control sensations lost through the use of power brake systems

Artificial feel systems

Visual braking indicators on the instrument panel

Adjustable friction locks on the rudder pedals

What is the purpose of the brake accumulator?

To dampen pressure surges from the hydraulic system while brakig

To ensure the bootstrap circuit will remain pressuerized in the event that both the hydraulic system pumps fail

To prvide enough hydraulic fluid, under pressure, to operate the brakes a set number of times, in the case of an emergency

What are the three components of the anti-skid system

Brake control valve, anti-skid control unit, and anti-skid control valves.

Wheel speed transducer, anti-skid contrl unit, and anti-skid control valves

Wheel speed transducer, anti-skid control unit, and brake accumulator

How are anti-skid control valves controlled

Electrically

Mechanically

Hydraulically

When inspecting brake wear pin indicators for brake lining serviceability, should the brakes be applied or released?

Released

Applied

Either

Which of the following is not a factor in the number of wheels and tires designed on an aircraft?

The max number of passengers the aircraft is designed to carry

The type of surface the aircraft is designed to land upon

The gross weight of the aircraft

What term is used to describe the drag associated with the extended landing gear, protruding into the slipstream?

External fairing drag

Component aero drag

Parasite drag

Which of the following is not one of the two ways the landing gear control the landing impact energy?

The shock is absorbed by converting the energy into heat energy

The shock energy is altered and transferred throughout the airframe at a different rate

The shock is absorbed by the pneumatic tires and refocused and transferred back to the landing surface

Identify the two types of shock absorbing landing gear used on aircraft?

Shock strut type and pneumatic tube type

Flexible leaf type and schock strut type

Flexible leaf type and hydraulic tube type

To which category do the landing skids of a helicopter belong?

Rigid gear

Leaf-type

Bungee type

In an air/oil shock strut, which camber contains the air or nitrogen charge?

Upper chamber

Lower chamber

Air charge moves between upper and lower chamber.

In an air/oil shock strut, upon landing, does the fluid flow past the metering pin increase or decrease as the strut further collapses?

Increases

Decreases

The flow is metered and regulated to remain constant

What compels the strut to extend after the initial impact, and corresponding collapse, of landing?

A large return spring integral to the shock absorber assembly

The gas charge in the upper cylinder that has become compress by the collapsing of the strut

The metering pin forces fluid to flow to the lower chamber, causing the strut to extend to the normal extension

What is the purpose of the nosewheel centering cams installed in the NLG shock strut?

To mechanically straighten the nosewheel when the shock strut is fully extended

To mechanically return the nosewheel to the centered position after a nosewheel steering command is removed

To provide alignment indication for reconnecting the torque links

In a MS28889 strut servicing valve, what must the technician do to bleed the gas charge from the strut during servicing

The technician must remove the valve core from the servicing valve

The technician must depress the valve core plunger

The technician must rotate the swivel nut sufficiently to allow the air to escape.

Which of the following describes the condition/alignment that would cause an aircrafts wheels to show a tendency to track toward the center of the fuselage as the aircraft moves forward?

Toe in

Toe out

Positive camber

Which of the following describes the condition/alignment whereby the tops of the wheels, when mounted on the aircraft, lean in to the fuselage?

Toe out

Negative camber

Positive camber

What is the name of the component, in retractable type landing gear systems, that is located on the top of the upper shock strut cylinder and attaches the strut to the airframe structures?

Torque mount

Trunnion

Integral landing gear mount

What is the purpose of the drag brace in a retractable type landing gear system?

It is used to restrain against the pivot action built into the trunnion attachment

It is used to prevent landing gear shimmy when in transit on the ground

It is used to ensure that the nosewheel is straight before retracting it into the wheel well

What device is used in landing gear systems that provides position indications without mechanical contact?

Microswitch

Transformer switch

Proximity sensor

What of the following is NOT a purpose of the NLG torque links?

Provides an attachment point for the tow bar

It prevents the shock strut from overextending during takeoff

It transfers the rotational input from the nosewheel steering NWS system to the nosewheel

What is the most common type of nosewheel steering system in small aircraft?

Electric

Mechanical

Electro-Hydraulic

Landing gear shimmy is described as

The tendency to oscillate rapidly, or shimmy, while extending and/or retracting the gear

The tendency to oscillate rapidly, or shimmy, under braking

The tendency to oscillate rapidly, or shimmy, at certain speeds

In a NWS system on a large transport category aircraft, from what two sources can the steering system receive input?

The yoke and rudder pedals

The steering tiller and rudder pedals

The steering tiller and yoke

If the NWS system fails, the system is said to revert to

Free-castering mode

Hydraulic lock mode

Standby mode

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