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Aircraft Systems > Landing Gear > Flashcards

Landing Gear Flashcards

1
Q

functions to provide a means of maneuvering the aircraft on the ground

A

landing gear

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2
Q

functions to support the aircraft at a convenient height to give clearance for propellers and to facilitate loading

A

landing gear

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3
Q

functions to absorb the kinetic energy of landing and provide a means of controlling deceleration

A

landing gear

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4
Q

Landing Gear Layout

A

tricycle layout, tailwheel or taildragger

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5
Q

nose wheel unit forward of two main gear units

A

tricycle layout

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6
Q

tail wheel behind the main wheels

A

tailwheel or taildragger

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7
Q

landing gear type fitted for slow, light aircraft, and some larger aircraft on which simplicity is of prime importance

A

fixed (non retractable) landing gear

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8
Q

The reduced performance caused by the drag of the landing gear (fixed landing gear) during flight is offset by the _______, ________, and ________.

A

simplicity, reduced maintenance, low initial cost

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9
Q

landing gear type utilized for higher performance aircraft because of more progressive drag; retracted into wings or fuselage during flight

A

retractable landing gear

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10
Q

downsides of retractable landing gear

A

increased weight, greater complication, additional maintenance

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11
Q

3 main types of fixed landing gear

A

spring steel leg, rubber cord (shock absorber), oleo-pneumatic struts

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12
Q

usually employed at the main undercarriage positions

A

spring steel legs

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13
Q

A spring steel leg consists of a ______ or tapered spring steel.

A

tube

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14
Q

In a spring steel legs, the upper end is attached by _____ to the _______ and the lower end terminating in the ______ on which the wheel and brake are assembled.

A

bolts, fuselage, axle

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15
Q

type of fixed landing gear used as a shock-absorber

A

rubber cord

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16
Q

In a rubber cord, the undercarriage is usually in the form of ________.

A

tubular struts

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17
Q

The undercarriage of a rubber cord is designed and installed so that the landing force is directed against a number of turns of rubber in the form of a ______ or ______.

A

grommet, loop

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18
Q

Some fixed main undercarriages and most fixed nose undercarriages are fitted with this type of fixed landing gear. What is this type of fixed landing gear?

A

oleo-pneumatic struts

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19
Q

In oleo-pneumatic struts, the design of individual struts _____ considerably but the operating principle is _____ for all.

A

varies, same

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20
Q

One point worthy of consideration in oleo-pneumatic struts is the fitting of _____ to oleo-pneumatic strut.

A

spats

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21
Q

an aerodynamic fairing which may be required to minimize the drag of the landing gear structure

A

spats

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22
Q

A simple oleo-pneumatic strut consists of _________, one free to slide inside the other.

A

two concentric cylinders

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23
Q

The cylinders in a simple oleo-pneumatic strut are filled with ________ and _____.

A

hydraulic fluid, gas

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24
Q

The hydraulic fluid and gas in the cylinders of oleo-pneumatic struts are kept apart by a _______.

A

separator piston

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25
Q

In a simple oleo-pneumatic strut, the outer or upper cylinder is attached to the ________.

A

airframe structure

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26
Q

In a simple oleo-pneumatic strut, the outer or upper cylinder houses the _______ and a _______.

A

inner or lower cylinder, piston assembly

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27
Q

In an oleo-pneumatic strut, these are connected to the bottom of the inner cylinder. What are these?

A

wheels, axle

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28
Q

In an oleo-pneumatic strut, the inner cylinder is ______ and move up and down within the outer cylinder.

A

free to rotate

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29
Q

In an oleo-pneumatic strut, _______ and up and down movement is limited by the _______.

A

rotary movement, torque links

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30
Q

In an oleo-pneumatic strut, what connects the inner and outer cylinders together?

A

torque links

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31
Q

What are other terms for torque links?

A

torsion or scissor links

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32
Q

Landing gear is subject to torsion loads during ground maneuvering and these loads are taken by the ________.

A

torque links

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33
Q

The ______ the radius of turn, the ______ will be the load felt by the torque links so all turns should be made as wide as possible.

A

smaller, greater

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34
Q

In an oleo-pneumatic strut, the are on the outer cylinder is filled with ______.

A

hydraulic fluid

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35
Q

In an oleo-pneumatic strut, the are on the inner cylinder is filled with _______ which may be _______ or _______.

A

compressed gas, air, nitrogen

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36
Q

It is a free-floating piston which keeps the fluid and gas apart.

A

separator piston

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37
Q

The _____ supports the weight of the aircraft on the ground, cushions bump during taxiing, and absorbs the _____ on landing.

A

gas, shock

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38
Q

Its purpose is to dampen oscillations and control the rate of compression and extension of the cylinders.

A

hydraulic fluid

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39
Q

In an oleo-pneumatic strut, the purpose of the hydraulic fluid is to _________ and control the rate of __________ of the cylinders.

A

dampen oscillations, compression and extension

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40
Q

The piston connected to the lower cylinder has _____ in it which restricts the flow of fluid through the piston, thus, dampening the movement between the cylinders.

A

holes

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41
Q

fitted to the lower cylinder piston assembly

A

flutter valve

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42
Q

consists of a free-floating circular plate with a large central hole

A

flutter valve

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43
Q

free to move up and down within its housing

A

flutter valve

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44
Q

In an oleo-pneumatic strut, on the top of the inner cylinder, there is a ________ plus a series of holes around the perimeter.

A

small central orifice

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45
Q

If the fluid is flowing upwards, the strut is ______.

A

extending

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46
Q

If the fluid is flowing downwards, the strut is ______.

A

contracting

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47
Q

If fluid is flowing ________, the plate will be pushed up with it, blocking off the outer holes and allowing a limited flow only through the central orifice.

A

upwards

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48
Q

If fluid is flowing ________, then the plate will be pushed down allowing a greater flow of fluid through all of the holes.

A

downwards

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49
Q

Flutter valve then limits the rate of movement, more restriction when _______, less restriction when ________.

A

extending, contracting

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50
Q

Determine the scenario:
the gas pressure will support the weight of the aircraft with the lower cylinder approximately on the midway of its stroke

A

Aircraft stationary on the ground

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51
Q

Determine the scenario:
cushioned by the gas pressure and dampened by the limited flow of fluid through the orifice

A

bumps during taxiing

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52
Q

Determine the scenario:
gas pressure will cause the lower part of the leg to extend to its fullest extent

A

takeoff

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53
Q

Determine the scenario:
strut shortens, and fluid is forced through the flutter valve

A

landing

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54
Q

As the downward force of the landing ______, the gas pressure acts as a spring and extends the strut.

A

decreases

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55
Q

The flutter valve plate will move with the fluid flow blocking off the outer holes and further reducing the speed of upward movement of the upper cylinder, thus, helping to prevent a ______ on landing.

A

bounce

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56
Q

Wheels to Leg Construction

A

fork, half fork, cantilever, dual wheel, multiwheel (bogie connected)

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57
Q

Employed to improve aircraft performance by reducing drag

A

retractable landing gear

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58
Q

In a retractable landing gear, it is provided to ensure that each undercarriage is locked securely in the retracted and extended positions.

A

mechanical locks

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59
Q

________ are installed by which the landing gear can be extended in the event of failure of the power source.

A

manual means

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60
Q

In a retractable landing gear, systems are provided to prevent ________ with the aircraft on the ground.

A

retraction

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61
Q

_________ are installed to guard against landing with the landing gear retracted.

A

warning devices

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62
Q

The geometrical arrangement and physical location of undercarriage units on aircraft is ___________.

A

by no means standard

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63
Q

The type, size, and position are decided at the _________, having already taken into account the many factors that must be considered.

A

design stage

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64
Q

the two main undercarriage units are positioned just aft of the center of gravity in this layout

A

tricycle layout

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65
Q

Tricycle layout support up to __% of the aircraft’s weight and all initial landing shocks.

A

90

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66
Q

In a retractable landing gear, the leg is attached to the wing spars by a ___________ on which the leg is free to rotate laterally.

A

cylindrical beam or trunnion

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67
Q

In a retractable landing gear, the leg is attached to the _______ by a cylindrical beam or trunnion on which the leg is free to rotate laterally.

A

wing spars

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68
Q

In a retractable landing gear, the upper part of the leg forms the ______ cylinder of the oleo-pneumatic strut.

A

outer

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69
Q

The strut inner cylinder is connected to the _______ or _______.

A

wheel bogie, truck beam

70
Q

It is able to pivot about its central point in a controlled way.

A

truck beam

71
Q

There is an _____ connected to a pair of _________ at each end of the truck beam.

A

axle, break wheels

72
Q

The _________ prevent rotation between the shock strut inner and outer cylinders without affecting their reciprocating action during normal operation of the strut.

A

wing gear torque links

73
Q

The ______ supports the leg in fore and aft direction.

A

drag strut

74
Q

The __________ support the leg laterally.

A

upper and lower side struts

75
Q

The upper and lower side struts fold out when the gear is lowered and are then held in place by the _______ which also folds out during extension.

A

jury strut

76
Q

It is pulled over center by the down lock actuator geometrically locking the gear down.

A

jury strut

77
Q

The jury strut is pulled over center by the _______ geometrically locking the gear down.

A

down lock actuator

78
Q

If the gear is lowered without hydraulic power, then the over centering action will be performed by an internal spring in the _________.

A

down lock actuator

79
Q

With no ______ available, provision has to be made for locking the undercarriage up and down.

A

geometric lock

80
Q

Depending on wheel layout, each wheel may require its own ________, and possibly even a steering motor.

A

shock absorber unit

81
Q

Depending on wheel layout, each wheel may require its own shock absorber unit, and possibly even a _______.

A

steering motor

82
Q

_________ to the undercarriage in flight allows manual lowering of the undercarriage in emergency.

A

ease of access

83
Q

Loads sustained by the landing gear

A
  • compressive loads
  • rearward bending loads
  • side loads
  • forward loads
  • torsional loads
84
Q

Determine the load:
landing and static on ground

A

compressive loads

85
Q

Determine the load:
during breaking

A

rearward bending loads

86
Q

Determine the load:
during cross wind landings, takeoffs, and taxiing

A

side loads

87
Q

Determine the load:
during push back

A

forward loads

88
Q

Determine the load:
ground maneuvering

A

torsional loads

89
Q

It is usually a lighter structure than a main unit since it carries less weight and is usually subject only to direct compression loads.

A

Nose Landing Gear

90
Q

It carries the attachment for the towing equipment and so must withstand shear loads as well.

A

Nose Landing Gear

91
Q

The design of a nose landing gear is complicated by several requirements which are:

A
  • castoring
  • self-centering
  • steering
  • anti-shimmy
  • can withstand shear loads
92
Q

the ability of the nose wheel to turn to either side in response to the results of differential braking, thrust, or aerodynamic forces on the rudder, and to return back to its central position when the forces are removed

A

castoring

93
Q

enables the aircraft to be maneuvered about the airfield

A

castoring

94
Q

___________ of the nose wheel is essential prior to landing gear retraction.

A

automatic self centering

95
Q

If the nose gear is not in a central position prior to its retraction, the restricted space available for its stowage will not be sufficient and severe damage may be caused to the aircraft structure as the hydraulic system forces the gear upwards.

A

wala lang, intindihin mo lang, pero sa nose wheel self-centering siya

96
Q

achieved by either a cam system or by hydraulic power through steering actuators

A

centering

97
Q

A method of steering is required to enable the pilot to maneuver the aircraft safely on the ground. Early methods involved the use of ________.

A

differential breaking

98
Q

_________ using hydraulic systems are now common to most large commercial aircraft, allowing the engines to be set at the minimum thrust for taxiing, thereby saving fuel, an important consideration with large jet engines.

A

powered steering

99
Q

A hydraulically powered system may include a cockpit __________, a _________ steering cylinders to hold the nose gear, and a ______________ to hold the nose wheel at the selected angle.

A

steering wheel or tiller, control valve, mechanical feedback device

100
Q

Steering is controlled depending on the type of aircraft by either the tiller or the operation of the __________.

A

rudder pedals

101
Q

In hydraulically controlled nosewheel steering systems, the operating pressure is derived from the _________.

A

aircraft hydraulic system

102
Q

Steering is only available when the gear is selected down. What gear?

A

landing gear

103
Q

There are two ________ which steer the nose gear.

A

steering actuators

104
Q

In some aircraft, a limited emergency supply may be provided by a __________.

A

hydraulic accumulator

105
Q

The _______ in the pipelines between the steering actuators provide dampening for the steering operation and help to prevent nose wheel shimmy.

A

restrictors

106
Q

The steering wheel or tiller is mechanically linked to the ________.

A

steering control valve

107
Q

The _________ is mechanically linked to the steering control valve.

A

steering wheel or tiller

108
Q

A _________ from the nose undercarriage gradually resets the control valve as the nose wheel turns.

A

follow-up linkage

109
Q

When the tiller is turned, it moves the ________ away from its central position.

A

control valve

110
Q

When the nosewheel reaches the selected angle, the _________ will centralize the control valve shutting off a fluid to the actuators.

A

follow-up linkage

111
Q

fitted between the two sides of the steering actuators

A

safety bypass valve

112
Q

normally held closed by hydraulic pressure

A

safety bypass valve

113
Q

purpose is to allow the nosewheel to castor if there is a hydraulic failure

A

safety bypass valve

114
Q

If the hydraulic system should fail, the spring will push open the valve allowing fluid to flow freely between the actuators thus allowing the nose wheel to _______.

A

castor

115
Q

Some systems have the facility to bypass the system during _______.

A

towing operations

116
Q

When operated, it opens the steering bypass valve.

A

bypass lever

117
Q

When the bypass lever is operated by ground operator at the nose gear location, it opens the valve allowing fluid to flow freely between the _______.

A

steering actuators

118
Q

A ______ with a flag attached is fitted to hold the lever in the valve open position.

A

bypass pin

119
Q

A bypass pin with a flag attached is fitted to hold the lever in the valve open position. The ______ can now tow the aircraft and turn the nosewheel as necessary.

A

tractor

120
Q

Large aircraft with ______ main gears have a problem with the main gears sliding sideways in turns.

A

multiwheel

121
Q

problem with the main gears sliding sideways in turns; can quickly damage tires

A

scrubbing

122
Q

o help improve the turning circle and reduce tire scrubbing, some aircraft have ________.

A

steerable body gear

123
Q

operates automatically in the opposite direction to the nose gear when the nose gear steering is operated

A

steerable body gear

124
Q

Due to the flexibility of tire sidewalls, an unstable rapid sinusoidal oscillation or vibration can happen into the nose undercarriage. What is the phenomenon called?

A

shimmy

125
Q

Worn or broken torque links, wear in the wheel bearings, and uneven tire brushes can all increase the tendency to _______.

A

shimmy

126
Q

_________ especially at high speeds can set up vibrations throughout the aircraft and can be dangerous.

A

excessive shimmy

127
Q

Best Ways to Keep Shimmy to a Minimum

A
  • maintain landing gear correctly
  • replacing worn-out parts
  • maintaining correct tire pressures
128
Q

A hydraulic or ________ can be attached between the upper and lower oleo-pneumatic strut cylinders.

A

spring shimmy damper

129
Q

Many larger aircraft use _______ to help reduce shimmy while _______ have been found to be effective in minimizing tail wheel shimmy.

A

double nose wheels, twin contact tires

130
Q

It is used to provide a positive indication to the crew of the operation of the locks and the position of the landing gear.

A

electrical indicating system

131
Q

The indicating system usually consists of _______ or _________ monitoring the up and down locks.

A

micro switches, proximity sensors

132
Q

These make or break electrical circuits when the locks operate causing indications to change on the landing gear position indicator on the instrument panel.

A

electrical indicating system

133
Q

________are simple mechanically operated electrical switches which are operated by a _______ when the gear reaches the required position.

A

micro switches, striker plate

134
Q

______ are electronic devices with no moving parts.

A

proximity switches

135
Q

Each proximity switch consists of two components which are:

A

sensor, target

136
Q

It is based on the proximity of the target and the sensor.

A

signal

137
Q

The sensors are usually duplicated for _________.

A

safety reasons

138
Q

________ may also be provided in some aircraft to show that the landing gear is down and locked if the electrical indicating system fails for the main gear.

A

mechanical indicators

139
Q

These are often just buttons which pop up on the top of the wing when the gear is locked down.

A

mechanical indicators

140
Q

The nose gear will often have some sort of ________ in the cockpit floor through which the down lock can be seen.

A

periscopic viewer

141
Q

Some aircraft don’t have mechanical indicators, instead they have ____________.

A

duplicated electrical down lock sensors

142
Q

is displayed when the undercarriage is locked down

A

green light

143
Q

is displayed when the undercarriage is in transit

A

red light

144
Q

are visible when the undercarriage is locked up

A

no lights

145
Q

are usually duplicated to avoid the possibility of false indications as a result of bulb failures

A

bulbs

146
Q

Many large aircraft also have ________ to indicate that the hydraulically operated doors are closed and locked.

A

main gear door lock indicators

147
Q

color of lights of main gear door lock indicators

A

red or amber

148
Q

The gear actuator and door actuator are _______.

A

double acting unbalanced actuators

149
Q

The gear is locked down by a ________.

A

geometric lock mechanism

150
Q

______ is hydraulically opened and closed.

A

door

151
Q

Door is ______ when the gear is locked up and _______ when the gear is locked down.

A

closed, opened

152
Q

It is a disagreement light; it illuminates at any time the gear and the lever are in disagreement so when the gear is selected up, the first thing that happens is that it illuminates. However, the gear is still locked down so the _______ remains.

A

gear red-light, green gear down light

153
Q

The _________ controlled by the gear lever will send _________ to the door actuator. The door now begins to open, and the door open light illuminates.

A

selector valve, pressure fluid

154
Q

The ________ will begin to retract breaking the geometric lock, the gear is now unlocked so it’s green gear down light will go out.

A

down lock actuator

155
Q

The gear actuator can now raise the gear when the gear is fully up the _____.

A

up lock

156
Q

Once the gear is locked up the _______ will go out.

A

red gear light

157
Q

Valve will direct the hydraulic fluid to the ________ and the door closes.

A

door actuator

158
Q

Once door is fully closed, the _________ will go out with the gear up and doors closed. There will be _____ lights on the indicator.

A

amber door open light, no

159
Q

Once the gear is up and locked and the door is closed, the gear lever is placed to the ________ leaving the gear unpressurized for the period of the cruise so extending the life of the landing gear components and preventing unwanted leakage of hydraulic fluid.

A

off position

160
Q

The sequence when the gear is selected down is basically the __________.

A

up sequence in reverse

161
Q

When the lever is selected down the red gear light comes on to indicate a ______ between the lever and the gear.

A

disagreement

162
Q

When the door is fully open, the valve will redirect the hydraulic fluid to the ________ and the _______. The gear actuator will now lower the gear assisted by the weight of the gear.

A

gear up lock actuator, gear actuator

163
Q

To control the speed of lowering, the returned fluid from the gear actuator passes through a _________ in the restricted flow direction.

A

one-way restrictive valve

164
Q

When the gear approaches the fully down position, a powerful spring in the lockdown actuator will push the geometric lock on the center, locking the gear ______. Red gear light goes out and the green light comes on.

A

down

165
Q

Once the gear is locked down, the door sequence valve directs fluid to the _______, door closes, and the door light ______.

A

door actuator, goes out

166
Q

When the gear is locked down, there are green down pointing triangles on both the undercarriage indicator and on the ________.

A

Electronic Centralized Aircraft Monitor (ECAM) screen

167
Q

What model of aircraft equips an ECAM and what does ECAM stand for?

A

Airbus A320, Electronic Centralized Aircraft Monitor

168
Q

When the gear is neither locked up nor down, the triangles on the ECAM screen are ____ and _______ is displayed on the landing gear indicator.

A

red, unlocked

169
Q

When the gear is up and locked, the displays on an ECAM screen are ______.

A

blank

170
Q

Door positions symbols on an ECAM screen are ______ when the doors are locked and closed, and _____, when they are not.

A

green, amber

Aircraft Systems (9 decks)

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