11.2 Aircraft Structures - General Concepts Flashcards

1
Q

when changing a component, what is the responsibility of the engineer?

A

to inspect the surrounding area for corrosion, fretting, cracking, pitting among others

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2
Q

what are aircraft structures designed to carry?

A

load or resist stress

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3
Q

what must every part of the aircraft be planned to carry?

A

loads imposed upon it

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4
Q

what type of analysis is completed to determine loads on aircraft structure?

A

stress analysis

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5
Q

what 3 types of structural design philosophies is there?

A
  • failsafe
  • damage tolerance
  • fatigue
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6
Q

what does the failsafe method rely on?

A

duplication of certain structural members

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7
Q

is the failsafe method purely for structural members?

A

no. (can be used in cabin windows for example)

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8
Q

what is the advantage of damage tolerance over failsafe?

A

damage can be detected during normal inspections before failure

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9
Q

how does the damage tolerance method differ from failsafe?

A

failure of one load member will not degrade structure, loads will transfer to other areas of the member

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10
Q

fracturing from a series of cyclic loading is known as what?

A

fatigue

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11
Q

what is fatigue?

A

ultimate static load the material can take

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12
Q

what is done to verify the fatigue life of aircraft structure?

A

fatigue testing, subjected to various loads. accurate prediction of life

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13
Q

what 3 types of structure is there?

A
  • primary
  • secondary
  • tertiary
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14
Q

what are the definitions for the 3 types of structure?

A
  • primary = critical load-bearing structure, may result in injury or death
  • secondary = not primary load bearing, failure wouldn’t reduce structural integrity,
  • tertiary = not load carrying members, don’t form an integral portion of the airframe
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15
Q

what are the 5 main structural units?

A
  • fuselage
  • wings
  • stabilisers
  • flight control surfaces
  • landing gear
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16
Q

what are airframe components made up of? [5]

A
  • stringers
  • ribs
  • frames
  • bulkheads
  • skins and others
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17
Q

what 6 types of strucural stresses are there?

A
  • tension
  • compression
  • torsion
  • shear
  • bending
  • hoop stress
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18
Q

what is hoop stress?

A

due to presurisation of the aircraft, stretching of aircraft and expansion of the circumference of skin

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19
Q

what is a body station?

A

vertical plane at right angle to the aircraft centre line

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20
Q

where is body station measured from?

A

predetermined position infront of the aircraft nose

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21
Q

what is the body buttock lines? and where do you look to determine this?

A

from the rear of the aircraft

parallel to the aircraft centre line, LBBL and RBBL

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22
Q

what is body water lines?

A

horizontal plane at the right angle to body station

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23
Q

Where is the body waterline measured from?

A

From the underneath the fuselage or the floor from inside the fuselage

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24
Q

What coordinates can be found on the wing? [3]

A
  • Wing reference plane
  • Wing buttock lines
  • Wing stations
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25
Q

How is the wing buttock line plane viewed?

A

Vertical plane at a right angle to the wing reference plane

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26
Q

How is wing station viewed?

A

At a right angle to the rear spar and wing reference plane

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27
Q

What coordinates are found on the nacelles? [3]

A
  • Nacelle stations
  • Nacelle buttock lines
  • Nacelle water lines
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28
Q

How is nacelle station viewed?

A

Vertical plane at a right angle to nacelle centreline

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29
Q

Where is nacelle station zero found on Boeing aircraft?

A

In front of the forward engine mount

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30
Q

What nacelle buttock line relative to?

A

Wing buttock line

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31
Q

What are nacelle waterlines?

A

Parallel to wing reference plane

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32
Q

Where is nacelle water line zero?

A

Below the nacelle

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33
Q

What coordinates are found on the horizontal stabiliser? [4]

A
  • Stabiliser chord plane
  • Buttock line stations
  • Leading edge stations
  • Elevator stations
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34
Q

What other name is there for stabiliser chord plane?

A

Horizontal stabiliser reference plane

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35
Q

What is stabiliser chord plane?

A

Plane through leading and trailing edges

36
Q

What is horizontal stabiliser buttock line?

A

At a right angle to the stabiliser chord plane and parallel to the body centre line

37
Q

What is stabiliser station?

A

Right angle to the stabiliser chord plane and to horizontal stabiliser rear spar

38
Q

What is stabiliser leading edge station?

A

Plane at a right angle to the horizontal stabiliser leading edge

39
Q

What is the elevator station?

A

Plane at a right angle to the elevator hinge centre line

40
Q

What coordinates can be found on the vertical stabiliser? [4]

A
  • Fin stations
  • Waterlines
  • Leading edge stations
  • Rudder stations
41
Q

What is fin station?

A

Plane at a right angle to the centre line of the vertical stabiliser rear spar

42
Q

What is fin water lines?

A

Horizontal plane parallel to body water line

43
Q

What is vertical stabiliser leading edge station?

A

Plane at a right angle to stabiliser leading edge

44
Q

What is rudder station?

A

Right angle to rudder hinge centre line

45
Q

What do airbus use to as a form of coordinates?

A

X Y Z with relevant axis’

46
Q

Which coordinate for airbus doesn’t have a negative value? Why?

A

X because you would be walking away from the aircraft

47
Q

How is nacelle station measured on airbus aircraft?

A

Zero located aft of body station

48
Q

What station will you find on horizontal and vertical stabilisers on airbus aircraft?

A

Horizontal stabiliser station and vertical stabiliser station

49
Q

How many major zones are there?

A

8

50
Q

Name the 8 major zones with there numbers?

A
100 = lower fuselage.          200 = upper fuselage
300= empennage.               400= left wing
500 = right wing.                  600 = engines
700 = landing gear              800 = doors
51
Q

How do you identify the right and left side of the aircraft in regards to zones?

A

Odd middle number = left hand side ( 110)

Even middle number = right hand side (120)

52
Q

What is required on the lower pressurised fuselage to prevent fluids becoming trapped?

A

Drain holes

53
Q

Where are drain holes fitted?

A

Lowest parts of the lower fuselage

54
Q

In drain holes, What is fitted to prevent loss of air during aircraft pressurisation?

A

Bilge-like valves

55
Q

in drain holes, What position are the valves when the aircraft are pressurised?

A

Closed position

56
Q

What basic protection is there for lightning?

A

Almost all metal external structure

57
Q

What does the external structure protect during lightning strikes?

A

Electrical systems and wiring from electromagnetic interference

58
Q

What 2 damage types may you find in a lightning strike?

A
  • Direct (surface burned)

- indirect (electrical damage)

59
Q

What does bonding provide?

A

Low resistance return path for single wire electrical systems

60
Q

What must be removed to ensure a low resistance connection for bonding leads?

A

Non-conducting paint and anodising films

61
Q

What is the process of connecting shields of shielded cables to the aircraft structure, called?

A

Grounding

62
Q

What is the name of sections of aircraft that are built in individual countries and assembled in one country called?

A

Manufactures joint or production break

63
Q

What two types of fuselage construction is there?

A

Truss type

Monocoque type

64
Q

What structural members does a truss type construction have? [3]

A
  • Beams
  • Struts
  • Bars
65
Q

What type of loads can a truss type fuselage carry? [2]

A
  • Tension

- compression

66
Q

What two types of monocoque construction is there? [2]

A
  • True monocoque

- Semi-monocoque

67
Q

What part of a true monocoque construction carries the primary stresses?

A

The skin

68
Q

What structural members are there within a true monocoque construction? [3]

A
  • Formers
  • frame assemblies
  • bulkhead
69
Q

In addition to Formers, frame assemblies and bulkhead, what else can be found in a semimonocoque construction?

A

Longitudinal members

70
Q

Where might you find steel and titanium in a semi monocoque construction?

A

Areas of high temperature

71
Q

What loads do longerons take?

A

Bending

72
Q

What is the purpose of stringers? [2]

A
  • Giving shape

- for attachment of the skin

73
Q

What will the thickness of the fuselage skin depend on? [2]

A
  • Load carried

- stress sustained

74
Q

What is the main advantage of a semi monocoque construction?

A

May withstand considerably more damage

75
Q

What are floor boards made out of ?

A

Honey comb composite construction

76
Q

What else is done when the floor is laid in “wet areas”?

A

Sealed to prevent corrosion

77
Q

How are the wings attached to the fuselage?

A

Via a wing box

78
Q

What are the wing boxes designed to provide?

A

Support and rigidity to the wings

79
Q

Generally, where is the wing box located?

A

At the strongest part of the fuselage

80
Q

What can the wing box absorb and distribute?

A
  • Stresses

- distribute across the supportive framework

81
Q

How is the horizontal stabiliser attached to the main fuselage?

A

Via Box section

82
Q

How is the vertical stabiliser attached?

A

Attached by large machined fittings

83
Q

What can be found in a nacelle strut assembly? [6]

A

-Torque box,
-Firewall and fire sealing
-Fairings
-Strut drains
-Fan cowl support beam
Engine attach fittings

84
Q

What 3 types of surface protection is there?

A
  • Pretreatment
  • Paint coatings
  • Special coatings
85
Q

What effects does cleaning an aircraft have? [2]

A
  • Decreases drag

- makes it more fuel efficient

86
Q

What must you use when cleaning an aircraft?

A

Water between 7 and 8 ph and a chlorine level of less than 100ppm