AF Aircraft Landing Gear Systems

Exposure to and/or storage near which of the following is considered harmful to aircraft tires?

Helium, fuel, oil, and low humidity.
Low humidity, helium, and ozone.
Fuel, oil, ozone, electrical equipment, hydraulic fluid, and solvents.

What would be the effect if the piston return spring broke in a brake master cylinder?

The brakes would become spongy.
The brake travel would become excessive.
The brakes would drag.

In brake service work, the term “bleeding brakes” is the process of

withdrawing air only from the system.
withdrawing fluid from the system for the purpose of removing air that has entered the system.
replacing small amounts of fluid in reservoir.

To prevent a very rapid extension of an oleo shock strut after initial compression resulting from landing impact,

various types of valves or orifices are used which restrict the reverse fluid flow.
the metering pin gradually reduces the size of the orifice as the shock strut extends.
the air is forced through a restricted orifice in the reverse direction.

A pilot reports the right brake on an aircraft is spongy when the brake pedal is depressed in a normal manner. The probable cause is

the hydraulic master cylinder piston is sticking.
air in the brake hydraulic system.
the hydraulic master cylinder piston return spring is weak.

Aside from an external leak in the line, what will cause parking brakes to continually bleed off pressure?

An internal leak in the master cylinder.
Insufficient hydraulic fluid in the reservoir.
Glazed brake linings.

Why do most aircraft tire manufacturers recommend that the tubes in newly installed tired be first inflated, fully deflated, and then reinflated to the correct pressure?

To allow the tube to position itself correctly inside the tire.
To eliminate all the air between the tube and the inside of the tire.
To test the entire assembly for leaks.

The metering pins in oleo shock struts serve to

lock the struts in the DOWN position.
retard the flow of oil as the struts are compressed.
meter the proper amount of air in the struts.

What action should be taken whenever maintenance is performed that will affect the landing gear system performance?

A test flight should be performed to conduct an operational check.
A technician with an inspection authorization should perform a visual inspection.
The aircraft should be paced on jacks and a retraction test should be performed.

When working with high-pressure, high-performance tires, why is it recommended to deflate the tires when removing wheels from the axle?

To relieve the strain on the wheel retaining nut and axle threads.
To ensure safety in case of a defective wheel or broken tie bolts.
To reduce the size of the tire for ease of removal.

The braking action of a Cleveland disk brake is accomplished by compressing a rotating brake disk between two opposite brake linings. How is equal pressure on both sides of the rotating disk assured?

By allowing the brake rotor to float to automatically equalize as pressure is applied to the rotor.
By allowing the caliper to float to automatically equalize as pressure is applied to the rotor.
By allowing the brake linings to automatically equalize as pressure is applied to the rotor.

If it is determined that spongy brake action is not caused by air in the brake system, what is the next most likely cause?

Worn brake lining.
Internal leakage in the master cylinder.
Deteriorated flexible hoses.

Many brake types can be adapted to operate mechanically or hydraulically. Which type is not adaptable to mechanical operation?

Single-disk spot type.
single-servo type.
Expander-tube type.

A brake debooster valve is installed in systems, where the high pressure of the hydraulic system (3,000 psi) is used to operate brakes

that are designed to work with lower pressure.
that are used in conjunction with an antiskid system.
that are used on aircraft having high landing speeds.

A stripe or mark applied to a wheel rim and extending onto the sidewall of a tube-type tire is a

slippage mark.
wheel-to-tire balance mark.
wheel weight reference mark.

When bleeding aircraft brakes, one of the indications that the air has been purged from the system is

partial brake pedal travel.
full brake pedal travel.
firm brake pedals.

Overinflated aircraft tires may cause damage to the

brake linings.
wheel hub.
wheel flange.

Debooster valves are used in brake systems primarily to

ensure rapid application and release of the brakes.
reduce brake pressure and maintain static pressure.
reduce the pressure and release the brakes rapidly.

The repair for an out-of-tolerance toe-in condition of main landing gear wheels determined not to be the result of bent or twisted components consists of

shimming the axle in the oleo trunnion.
inserting, removing, or changing the location of washers or spacers at the center pivotal point of the scissor torque links.
placing shims or spacers behind the bearing of the out-of-tolerance wheel or wheels.

On an air valve core start, what indicates high-pressure type?

An embossed letter “NP.”
An embossed letter “HP.”
An embossed letter “H.”

The primary purpose for balancing aircraft wheel assemblies is to

prevent heavy spots and reduce vibration.
distribute the aircraft weight properly.
reduce excessive wear and turbulence.

Power boost brake systems are used on aircraft that have

high landing speeds.
low normal hydraulic system pressure.
more than one brake assembly per axle.

On all aircraft equipped with retractable landing gear, some means must be provided to

retract and extend the landing gear if the normal operating mechanism fails.
extend the landing gear if the normal operating mechanism fails.
prevent the throttle from being reduced below a safe power setting while the landing gear is retracted.

An automatic damping action occurs at the steering damper if for any reason the flow of high-pressure fluid is removed from the

outlet of the steering damper.
inlet of the steering damper.
replenishing check valve.

What is the purpose of the torque links attached to the cylinder and piston of a landing gear oleo strut?

Limit compression stroke.
Hold the strut in place.
Maintain correct wheel alignment.

The removal, installation, and repair of landing gear tires by the holder of a private pilot certificate on an aircraft owned or operated is considered to be

a violation of the Federal Aviation Regulations.
a minor repair.
preventive maintenance.

Aircraft brakes requiring a large volume of fluid to operate the brakes generally

use independent master cylinder systems.
do not use brake system accumulators.
use power brake control valves.

What is one event a restricted compensator port of a master cylinder will have on a brake system?

The brakes will operate normally.
The reservoir will be filled by reverse flow.
The restriction will cause slow release of the brakes.

When an airfoil type of landing gear shock strut is used, the initial shock of landing is cushioned by

compression of the air charge.
the fluid being forced through a metered opening.
compression of the fluid.

Internal leakage in a brake master cylinder unit can cause

fading brakes.
slow release of brakes.
the pedal to slowly creep down while pedal pressure is applied.

A sleeve, spacer, or bumper ring is incorporated in a landing gear oleo shock strut to

limit the extension of the torque arm.
limit the extension stroke.
reduce the rebound effect.

The purpose of a sequence valve in a hydraulic retractable landing gear system is to

prevent heavy landing gear from falling too rapidly upon extension.
provide a means of disconnecting the normal source of hydraulic power and connecting the emergency source of power.
ensure operation of the landing gear and gear doors in the proper order.

The pressure source for power brakes is

the main hydraulic system.
the power brake reservoir.
a master cylinder.

Which statement is true with respect to an aircraft equipped with hydraulically operated multiple disk type brake assemblies?

There are no minimum or maximum disk clearance checks required due to the use of self-compensating cylinder assemblies.
Do not set parking brake when brakes are hot.
No parking brake provisions are possible for this type of brake assembly.

What type of valve is used in the brake actuating line to isolate the emergency brake system from the normal brake control valve system?

A bypass valve.
An orifice check valve.
A shuttle valve.

When servicing an air/oil shock strut with MIL-5606 the strut should be

collapsed and fluid added at the filter opening.
fully extended and fluid added at the filter opening.
partially extended and fluid added at the filter opening.

Instructions concerning the type of fluid and amount of air pressure to be put in a shock strut are found

on the airplane data plate.
in the aircraft operations limitations.
in the aircraft manufacturer’s service manual.

The purpose of a relief valve in a brake system is to

reduce pressure for brake application.
prevent the tire from skidding.
compensate for thermal expansion.

Aircraft tire pressure should be checked

using only a push on stick-type gauge having one-pound increments.
at least once a week or more often.
as soon as possible after each flight.

If the extended longitudinal axis of the main landing gear wheel assemblies intersects aft of the aircraft, the wheels can be termed as having

toe-out.
toe-in.
negative camber.

What is the purpose of a compensating port or valve in a brake master cylinder of an independent brake system?

Permits the fluid to flow toward or away from the reservoir as temperature changes.
Assists in the master cylinder piston return.
Prevents fluid from flowing back to the reservoir.

If an aircraft shock strut (airfoil type) bottoms upon initial landing contact, but functions correctly during taxi, the most probable cause is

low fluid.
low air charge.
a restricted metering pin orifice.

What is the function of a cam incorporated in a nose gear shock strut?

Provides an internal shimmy damper.
Straightens the nosewheel.
Provides steering of aircraft during ground operation.

Extension of an oleo shock strut is measured to determine the

amount of oil in the strut.
physical condition of the strut itself.
proper operating position of the strut.

Debooster cylinders are used in brake systems primarily to

reduce brake pressure and maintain static pressure.
relieve excessive fluid and ensure a positive release.
reduce the pressure to the brake and increase the volume of fluid flow.

If a shock strut bottoms after it has been properly serviced, the

strut should be disassembled and the metering pin orifice plate replaced.
air pressure should be increased.
strut should be removed, disassembled, and inspected.

A high-speed aircraft tire with a sound cord body and bead may be recapped

a maximum of three times.
only by the tire manufacturer.
an indefinite number of times.

If an airplane equipped with master cylinders and single-disk brakes has excessive brake pedal travel, but the brakes are hard and effective, the probable cause is

the master cylinder one-way cup is leaking.
worn brake linings.
worn brake disk causing excessive clearance between the notches on the perimeter of the disk and the splines or keys on the wheel.

The correct inflation pressure for an aircraft tire can be obtained from

tire manufacturer’s specifications.
the aircraft service manual.
the information stamped on the aircraft wheel.

What should be checked when a shock struct bottoms during a landing?

Air pressure.
Packing seals for correct installation.
Fluid level.

How is it determined in a master cylinder brake system that all of the air has been purged from the system?

By operating a hydraulic unit and watching the system pressure gauge for smooth, full scale deflection.
By depressing the brake and noting that the brake is firm and not spongy.
By measuring the amount of fluid return to the master cylinder upon brake release.

The left brake is dragging excessively on an airplane on which no recent brake service work has been performed. The most probable cause is

foreign particles stuck in the master cylinder compensating port.
excessively worn brake linings.
low fluid supply in the brake system reservoir.

If a brake debooster is used in a hydraulic brake system, its position in the system will be

between the pressure manifold of the main hydraulic system and the power brake control valve.
between the brake control valve and the brake actuating cylinder.
in the brake pressure line between the brake pedal and the brake accumulator.

The hydraulic packing seals used in a landing gear shock strut are

generally designed to be compatible with more than one type of fluid.
kept from direct contact with fluid by Teflon or nylon backup rings.
used only with a specific type of fluid.

Lockout deboosters are primarily pressure reducing valves that

allow full debooster piston travel without fluid from the high pressure side entering the low pressure chamber.
cannot allow full debooster piston travel without fluid from the high pressure side entering the low pressure chamber.
must be bled separately after brake bleeding has been completed.

A close inspection of a fusible plug reveals the core has experienced some deformation. What is the appropriate maintenance procedure?

Replace all the fusible plugs.
Replace the affected fusible plugs.
Replace with new wheel assembly.

Chines are used on some aircraft nose wheel tires to help

nose gear extension at higher air speeds.
reduce the possibility of hydroplaning.
deflect water away from the fuselage.

The best safeguards against heat buildup in aircraft tires are

proper tire inflation, minimum braking, and ground rolls into the wind.
short ground rolls, slow taxi speeds, minimum braking, and proper tire inflation.
minimum braking, proper tire inflation, and long ground rolls.

The fusible plugs installed in some aircraft wheels will

indicate tire tread separation.
prevent overinflation.
melt at a specified elevated temperature.

What action, if any, should be taken when there is a difference of more than 5 pounds of air pressure in tires mounted as duals?

Replace both tires.
Correct the discrepancy and enter in the aircraft records.
Replace the tire with the lowest pressure.

How long should you wait after a flight before checking tire pressure?

At least 2 hours (3 hours in hot weather).
At least 3 hours (4 hours in hot weather).
At least 4 hours (5 hours in hot weather).

What is the minimum amount of time to wait for tires to cool before checking tire pressure?

3 hours.
2 hours.
1 hour.

Excessive wear in the shoulder area of an aircraft tire is an indication of

overinflation.
excessive toe-in.
underinflation.

Excessive wear in the center of the tread of an aircraft tire is an indication of

misalignment.
underinflation.
overinflation.

When servicing an empty shock strut with fluid, the strut should be completely compressed and extended several times to ensure

the piston rod and wiper are lubricated with hydraulic fluid.
all excess hydraulic fluid is forced out of the strut.
proper packing ring seating and removal of air bubbles.

In shock struts, chevron seals are used to

absorb bottoming effect.
prevent oil from escaping.
serve as a bearing surface.

On most aircraft, the oil level of an air and oil shock strut is checked by

removing the oil filter plug and inserting a gauge.
measuring the length of the strut extension with a certain air pressure in the strut.
releasing the air and seeing that the oil is to the level of the filter plug.

A pilot reports that the brake pedals have excessive travel. A probable cause is

weak return springs.
lack of fluid in the brake system.
oil or some foreign matter on the brake rotors and linings.

When will a continuous horn provide a warning in the cockpit?

When the throttle is retarded and gear is not down and locked.
When the throttle is advanced and gear is down and locked.
When the throttle is retarded and gear is down and locked.

An electric motor used to raise and lower a landing gear would most likely be a

shunt field series-wound motor.
split field shunt-wound motor.
split field series-wound motor.

When installing a chevron-type seal in an aircraft hydraulic cylinder, the open side of the seal should face

opposite the direction of fluid pressure.
up or forward when the unit is installed in a horizontal position.
the direction of fluid pressure.

Nose gear centering cams are used in many retractable landing gear systems. The primary purpose of the centering device is to

align the nosewheel prior to touchdown.
engage the nosewheel steering.
center the nosewheel before it enters the wheel well.

What device in a hydraulic system with a constant-delivery pump allows circulation of the fluid when no demands are on the system?

Pressure relief valve.
Shuttle valve.
Pressure regulator.

A fully-charged hydraulic accumulator provides

air pressure to the various hydraulic-components.
a source for additional hydraulic power when heavy demands are placed on the system.
positive fluid flow to the pump inlet.

A hydraulic system referred to as a “power pack” system will

have an engine-driven pump for greater pressure.
have all hydraulic power components located in one unit.
have a pressurized reservoir.

A flexible hydraulic hose identified as MIL-H-8788 will have a stripe running the length of the hose. This stripe is

installed without excessive twisting.
for high pressure fluids with a flexing range.
suitable for a wide temperature range.

An O-ring intended for use in a hydraulic system using MIL-H-5606 (mineral base) fluid will be marked with

a blue stripe or dot.
one or more white dots.
a white and yellow stripe.

What condition would most likely cause excessive fluctuation of the pressure gauge when the hydraulic pump is operating?

Accumulator air pressure low.
Inadequate supply of fluid.
System relief valve sticking closed.

A filter incorporating specially treated cellulose paper is identified as a

sediment trap.
CUNO filter.
Micronic filter.

The purpose of an orifice check valve is to

relieve pressure to a sensitive component.
restrict flow in one direction and allow free flow in the other.
relieve pressure in one direction and prevent flow in the other direction.

Refer to Figure 10. The trunnion nut on an aircraft landing gear requires a torque of 320 inch-pounds. To reach the rut, a 2-inch straight adapter must be used on an 18-inch torque wrench. How many foot-pounds will be indicated on the torque wrench when the required torque of the nut is reached?

24.
28.8.
22.

A special bolt in a landing gear attachment requires a torque value of 440 inch-pounds. How many foot-pounds are required?

36.8.
38.
36.6.

AF Aircraft Landing Gear Systems

Jon K

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