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Module 11 Richard > 11.9 Flight Controls > Flashcards

11.9 Flight Controls Flashcards

1
Q

How would you know how flexible a cable is

A

The more wires in a strand the more flexible a wire is

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2
Q

A cable is identified by what 3 characteristics

A
  • The diameter
  • The number of strands
  • The number of wires in each strand
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3
Q

What types of cables are used when several changes of direction occur

A

Extra flexible cables

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4
Q

What is an obvious advantage of a cable flight control system over rods and levers

A

Cables weigh much less

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5
Q

What is an obvious disadvantage of using cable flight control systems over rods and levers

A

Cables cannot transmit push forces

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6
Q

What provides a more reliable control transmission cables or rods

A

Cables

As long as cables are inspected regularly they provide a safer transmission method

Rods will break suddenly with out warning

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7
Q

What must be done to cables on a regular basis

A

They must be cleaned, inspected and lubricated on a regular basis

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8
Q

What can be used to remove old grease, dirt or lubrication from control cables

A

A lint free cloth

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9
Q

Why can’t solvents be used to clean control cables

A

They remove grease and lubrication from inside the cable

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10
Q

How would you detect a broken wire on the outside of a cable

A

Running a lint free cloth along the outside of the cable

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11
Q

How would internal wires in a cable be detected

A

By bending the cable

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12
Q

What is used to protect cables from corrosion

A

They are lightly lubricated

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13
Q

As a cable is only capable of pulling forces, what would be used in the transmission run to close a component after being opened

A

A spring

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14
Q

What do duel cable transmissions use to transmit push and pull rod movements to cables

A

Quadrents

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15
Q

What are the 3 main types of quadrant used

A
  • Normal quadrents
  • Single quadrents
  • Tension quadrents
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16
Q

What ensures that tension in a cable system is kept at a constant even at different temperatures

A

A cable tension regulator

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17
Q

What does a cable tension regulator consist of

A
  • Two quadrent halves mounted on a common axle
  • A spring loaded cross head mounted on a guide
  • Pull rods
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18
Q

What are cable pulleys used for

A

To change direction in the control run

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19
Q

What is used to prevent cables from jumping off pulleys

A

Safety pins and guides

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20
Q

What are used around a cable when it’s being passed through a pressure bulkhead to create an air tight seal

A

Pressure seals

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21
Q

What are fairleads used for

A

To guide and support a cable along its routing

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22
Q

Fairleads allow a maximum cable direction change of how many degrees

A

3 degrees

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23
Q

What is a turnbuckle used for

A

To connect two externally threaded barrel ends

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24
Q

What do adjustable rods consist of

A
  • Inner and outer lock washer
  • A lock nut
  • An inspection hole to check for minimum screw penetration
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25
Q

What are chains used for in a control run

A

To transmit forces to and from a cable system

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26
Q

What are the main components of a chain installation

A
  • The chain
  • The wheel
  • The protection guards
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27
Q

What are torque shafts used for

A

To transmit torque for linear movements

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28
Q

What are torque tubes used for

A

To transmit torque for rotary movements

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29
Q

What are the 4 types or gearbox and gearing that torque tubes use

A
  • Angle gearboxes
  • Offset gearboxes
  • Rotary actuators
  • Differential gearing
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30
Q

What is a rotary actuator used for

A

To transmit torque tube rotation to an output lever

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31
Q

What is a differential gear

A

A differential gear connects one output shaft with two independently operating motors

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32
Q

What are screwjack transmissions used for

A

To convert rotary inputs to linear movements

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33
Q

What are the main components of a screw jack transmission

A
  • The transmission gearbox
  • The screwjack
  • The ball nut
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34
Q

What is used to achieve high torque transmission with less friction

A

A ball screw jack

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35
Q

What is the no- back break used for

A

The no- back break is incorporated in the gearbox to hold the ball screw jack in its last position

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36
Q

What are the main components of a no back break

A
  • A ratchet wheel
  • Pawl
  • A break disk
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37
Q

How is excessive torque prevented

A

A torque limiter

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38
Q

What are the main components of a torque limiter

A
  • A friction break
  • A ball ramp device with input and output members
  • Springs which are preloaded to approx 120% of maximum operating torque
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39
Q

What are override devices sometimes known as

A

Load limiters

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40
Q

What are override devices used for

A

Used to prevent a complete jamming of a flight control system when one component is jammed

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41
Q

What are the 3 main override devices

A
  • Force detents
  • Shear rivets
  • Force limiting struts
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42
Q

What are the main components of a force detent

A
  • A cam
  • A lever
  • A spring loaded roller
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43
Q

What is the simplest form of load limiter

A

Shear rivets

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44
Q

How would you inspect a shear rivet

A

An inspection hole

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45
Q

What is a feel unit

A

In a hydraulic transmission the pilot cannot feel the force on the air directly so the feel unit is installed

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46
Q

Typically how many servo control units power each flight control

A

2 independently controlled units

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47
Q

What is used to restrict flight controls from flapping around in the wind whilst on the ground with no power

A

A dampening mode and restricted orifice

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48
Q

What is the advantage of a EHA (Electro Hydraulic Actuator)

A

The power for the EHA does not come from an external system but from an electric motor inside the unit, this saves weight as there is no need for heavy plumbing and fluid

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49
Q

What ATA chapter is flight controls

A

ATA 27

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50
Q

What does a hydraulic system require to provide the pilot with an artificial feel of the air load and to bring a deflected surface back to a neutral position

A

A feel unit

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51
Q

What are the two different feel unit designs

A
  • A spring design

- A cam design

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52
Q

Why would a feel unit be required

A

With out a feel unit the pilot would be able to achieve full deflection of a control surface and could overstress the aircraft

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53
Q

What does the trim unit consist of

A

A electronic motor operated screw jack

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54
Q

When rigging an aircraft flight control, what is used to help determine the control surface is in the correct position

A

Rigging pins

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55
Q

As cable tension varies with temperature, how long must the aircraft temperature be stable for before the cable system is checked

(When rigging)

A

At least 1 hour

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56
Q

In transmission systems with out a tension regulator what must be used to measure the tension

A

A tensiometer

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57
Q

How are control cables adjusted

A

By adjusting the turnbuckles

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58
Q

Where would the correct tension for control cables be found

A

AMM

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59
Q

When adjusting turnbuckles how many threads is the limit from being exposed outside the terminal

A

3

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60
Q

When rigging a hydraulic operated surface what must be done first

A

The system must be pressurised

61
Q

What is the minimum amount of control surfaces that is required to test flight control around all 3 aircraft axis

A

Minimum of 2 systems

62
Q

How is hydraulic power supplied to the control surfaces

A

Through shut off valves

63
Q

What is used to give priority to flight controls when there are many users

A

Priority valves

64
Q

When would you see a stabiliser config warning

A

Usually before take off. Due to the stabiliser not being in the correct position for flight

65
Q

When can you do a take off warning test and why would you do one

A

With the aircraft on the ground without the engines running.

The test simulates engines at full power

66
Q

There are two aileron control wheels in the cockpit, of for f/o and one for captain, what are they connected by

A

Cables known as bus cables and a load limiter

67
Q

What are the two aileron trim switches

A

One for arm and one for the controlling movement

68
Q

What system is aileron position shown

A

EICAS (Engine Indication and Crew Alerting System)

69
Q

What is the purpose of a load limiter

A

Allows control wheels to be disconnected if one gets jammed

70
Q

What does CLCP stand for

A

Central Lateral Control Package

71
Q

What is the purpose of CLCPs

A

The convert electrical inputs from the autopilot to hydraulically powered outputs to the aileron programmers

72
Q

What is a lost motion device used for

A

To prevent undesired feedback from the right body cable to the control wheels

Up to 6 degrees either way is permitted

73
Q

What do the aileron programmers do

A

Control the relationship between the control wheels and deflection of the ailerons

74
Q

What problems does differential ailerons prevent

A

Avoids negative turning movement

75
Q

What is the basic function of the rudder

A

To control the aircraft around the vertical axis and control yaw movement

76
Q

On large aircraft what are the 3 main functions of the rudder

A
  • Trim the aircraft
  • For turning along with ailerons and spoilers
  • For Dutch roll damping
77
Q

How is the rudder operated

A

With the rudder pedals, pilots and co pilots are interconnected

78
Q

What do the rudder pedals operate on the ground

A

Nose wheel steering and the brakes

79
Q

What controls rudder trim

A

It is controlled electronically via the rudder trim computer

80
Q

Where is the rudder position shown

A

One the EICAS (Engine Indication and Crew Alerting System)

81
Q

What is different about the elevator feel system compared to other aircraft feel systems

A

The elevator system is a bit more complicated and required information on airspeed and aircraft loading from the FMC to prevent any dangerous manoeuvres

82
Q

Where is the elevator feel unit found

A

In the tail section of the aircraft

83
Q

The elevator feel unit needs to send signals to the control column depending on the speed and loading what is used to modulate this

A

It is supplied with a feel pressure by the elevator feel computer which depends on aircraft speed and loading

84
Q

What does the electronic feel computer do when it detects a change in dynamic air pressure on the control surface

A

It controls hydraulic pressure inputs to the feel actuator

85
Q

What are the main components of a Electrical Flight Control System (EFCS) also known as fly by wire

A
  • Electrical Flight Control computes

- Sensors and wires for the input and output signals

86
Q

What are the components in a conventional flight control system

A
  • The cockpit controls
  • The transmission system with cables and quadrents
  • The hydraulic actuator and the flight control surface
87
Q

What is the purpose of a fly by wire system

A

Saves weight and makes maintenance easier

88
Q

What additional information along with the control I put would the electronic flight computers need to calculate the output order and ensure a smooth, economic and safe operation

A
  • Aircraft roll and pitch attitude
  • Airspeed
  • Accelerations
  • Angle of attack
  • Flight/Ground status
89
Q

What happens to the electronic flight control system when the aircraft is in autopilot rather than manual

A

The autopilot provides the inputs to the computers rather than the side stick

90
Q

What turns electrical signals from electronically controlled flight computers to a mechanical motion

A

Hydraulically operated servo controlled actuators

91
Q

Two independent servo controlled actuators are used for each rudder and aileron, what is the second used for

A

As a redundancy and provides a damping function

92
Q

What is the white cross on the primary flight display for on Airbus

A

Allows the pilot to test the side sticks during pre flight check

93
Q

The EFCS computers for fill safety requirements in what 3 ways

A
  • A minimum of 2 different types of computers are used. Each have completely different software and hardware
  • Calculations are done independently on 2 different channels
  • There is only an output signal if both channels have the same result
94
Q

What happens if there is a complete failure of the EFCS

A

There will be a mechanical backup to land the aircraft safely

95
Q

How many of the EFCS computers are connected to a backup source of power

A

Minimum of 3

96
Q

What changes in the EFCS when the aircraft is on the ground compared to being in the air

A

On the ground the computer uses direct law and in the air it uses normal law

97
Q

How can the aircraft be operated with the flight computers in normal mode rather than in the ground in direct mode

A

Normal mode in the air the aircraft can be controlled on all 3 axis and and is in flight mode whereas on the ground only the ailerons, spoilers and elevators can be operated

98
Q

What are the three groups of protection circuits are there which prevent wrong flight control orders being imputed and causing a dangerous situation

A
  • Attitude limits
  • Airspeed limits
  • G load limits
99
Q

How much g load is a typical aircraft structure designed to resist

A

+2.5g and -1g

100
Q

Does the amount of g load that the aircraft airframe is able to resist change when the flaps are extended.

A

Yes to +2 and 0g

101
Q

How would you be able to tell if a protection circuit is active

A

A double green line is shown on the primary flight display

102
Q

What is alpha protection

A

At low speeds alpha protection prevents the angle of attack becoming too great for the speed of the aircraft and creating a stall even in the yolk is moved backwards

103
Q

What special functions do the electronic flight control computers have apart from their normal operational functions and protections

A
  • Auto ground spoiler control
  • Yaw damping
  • Rudder Tavel limitation
  • Load alleviation
104
Q

What does the load alleviation function do

A

Stops the wings from being bent beyond operational limits. Increases life of the aircraft

105
Q

What large surface is used for pitch trim

A

The horizontal stabiliser

106
Q

Why would the whole horizontal stabiliser need to move instead of just the elevators

A

As there is a greater imbalance on the longitudinal axis and it is more economical to use the horizontal stabiliser

107
Q

How is the horizontal stabiliser controlled from the cockpit

A

There is one set on each control wheel, and the set comes as a arm and control switch. Once the arm switch has been activated then the control valve will open and allow the hydraulic pressure to move the control one the second switch is then pressed.

Both need to be pressed for a movement to occur

108
Q

What are the main components of a trimmable horizontal stabiliser drive mechanism

A
  • A screw jack with a ball nut
  • A differential gear
  • Two hydraulic motors
  • A primary and a secondary brake
109
Q

What prevents the stabiliser from moving up and down due to aerodynamic loads

A

An irreversible pawl controlled ratchet

110
Q

What are the purpose of the stabiliser trim control modules

A

There are two completely identical independent modules.

They send hydraulic pressure to the drive mechanism.

111
Q

What prevents the stabiliser from going out of range of safe flight

A

Limit switches and mechanical stops

112
Q

What are the stabiliser pitch trims wheels connected to help carry out their command

A

They are connected to gears and chains which as then connected to cables below the pedestal.

The input from the wheels is transmitted via the cables to the aft chain and from the aft chain to the input shaft on the actuator

113
Q

How does the ball nut of the screw jack transmit the motion of the drive mechanism to the attachment fittings which will deflect the surface

A

Via a gimble

114
Q

How is the stabiliser position shown on the displays in the cockpit

A
  1. Electronic Centralised Aircraft Monitor (ECAM) system display
  2. On a scale with a pointer adjacent to the pitch trim wheels
  3. On a moving scale on the pedestal
  4. On the aircraft body adjacent the stabiliser leading edge
115
Q

What is tuck under

A

The centre of lift moves forward as the MACH no increases.

The result is a pitch down effect which would increase the Mach number. As this is an unstable condition it must be avoided

116
Q

What is the purpose of the Mach trim sub system

A

Counteracts or prevents the tuck under effect by moving the stabiliser leading edge down when the Mach number increases

117
Q

What computer supplies the Mach number and what would then calculate the necessary trim command to prevent tuck under

A

The air data computer would supply the Mach number and then the trim computer calculates the required deflection depending on the aerodynamic characteristics of the aircraft

118
Q

What are considered as high lift devices

A

Flaps and slats

119
Q

How do flaps contribute to being high lift devices

A

They change the camber of the wing and some also increase the surface area

120
Q

What high lift flaps are normally found on Airbus aircraft

A

Fowler flaps

121
Q

What high lift flaps are mostly used on Boeing aircraft

A

Triple slotted flaps

122
Q

What are the 4 different types of leading edge high lift devices

A
  • Leading edge flaps (Kruger flaps)
  • Variable camber flaps
  • Slats
  • Droop nose
123
Q

What are Krueger flaps also known as

A

Leading edge flaps

They are the upper side of the wing when retracted

124
Q

What does the variable camber flap consist of

A
  • A fibre glass panel
  • A folding nose
  • Many rods and levers
    Operated via a drive arm of a rotary actuator
125
Q

When the slats are extended it creates a slot, what does this do to the air

A

It allows air from the high pressure area under the wing to come up and flow over the wing

126
Q

How does a droop nose work

A

A rotary actuator moves the complete leading edge of the wing so increase the camber

127
Q

Why does the flap lever have gates at detents 1 and 20

A

T prevent the handle being moved past these detents with out stopping

128
Q

What happens to the slats and flaps in the landing position

A

They are both fully extended and full extension

129
Q

What are the effects of slots in the flaps

A

High pressure air from underneath the wing is able to travel through the slot to the top of the wing re energising airflow and delaying flow separation

130
Q

How does the drive system operate the flaps

A

Via torque tubes, rotary actuators and tracks

131
Q

If one electronic flap slat computer fails can it also take on the work of another

A

Yes but only at 50% of the speed

132
Q

If all 3 flap slat computers fail and there is no hydraulic supply how can they still be extended and retracted

A

Via an electric motor

133
Q

What two variations of independent power systems do the flaps and leading edge devices have

A
  • Two independent hydraulic systems
  • One hydraulic and one electric
  • One Pneumatic and one electric
134
Q

What is a PCU

A

Power control unit

For flaps and slats

135
Q

If there is a single failure in the flap slat system will it continue to operate

A

Yes but with only 50% of normal speed

136
Q

What angle of attack gives maximum lift

A

14 degrees

137
Q

What is alpha lock

A

A system to prevent the flaps being retracted to prevent stall

If the angle of attack is 10 degrees with flaps deployed, the angle would go higher if they are retracted hence why with alpha lock engaged they cannot retract and thus cannot stall

138
Q

What is the load relief system/ overload protection

A

Flaps retract automatically from the full position to the take off position if the airspeed is too high. This prevents damage to the flaps

139
Q

What is important regarding flaps and slats before turning hydraulic power on

A

The handle must be in the same position os the flaps the selfs

140
Q

Why should flaps not be operated too much during maintenance

A

To prevent the electric motors overheating

141
Q

What are the 3 main functions of the spoilers

A
  • Used as speed brakes during flight
  • As roll spoilers to assist ailerons
  • As ground spoilers after touch down
142
Q

Why do the spoilers never go to full deflection during flight

A

To prevent disturbing the airflow to the horizontal stabiliser

143
Q

What are the spoilers powered by

A

Actuators which as electrically controlled by flight control computers

144
Q

What are the speed brakes 3 positions

A
  • Down
  • In flight
  • Up
145
Q

How can the speed brakes be operated from the cockpit

A

Manually via the speed brake leaver or automatically via the auto spoiler actuator

146
Q

What is necessary to have on the speed brake lever to prevent dangerous situations during flight

A

He lever is limited by a energised lock lever solenoid and the extended stop

147
Q

What must be done to the speed brake lever on the ground during maintenance

A

A locking device must be installed to prevent unintended injury

148
Q

What are the three operating modes of servo control actuators for the spoilers

A
  1. Active mode - Used to extend or retract the spoilers with hydraulic pressure
  2. Blow down mode - Used in the event of pressure loss
  3. The locked mode - Used to prevent spoiler extension with out pressure

Module 11 Richard (19 decks)

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