11.2 Airframe Structures - General Flashcards

1
Q

What must be done if a defect is found on an aircraft

A

It must be noted in the logbook so it can be rectified with an approved drawing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What type of loads do structural members usually carry

A

End loads rather than side loads

Tension or compression rather than bending

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Rather than taking structural loads what qualities are required from fairings and cowlings

A

They need to have a neat appearance and streamlined shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Every part of the aircraft must be planned to take the load to be imposed on it what is this process called

A

Stress analasys

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

To ensure the aircraft structure is capable of taking all of the stresses it will experience in flight what is done in the initial design phase

A

Fail safe load transfer, damage tolerance and fatigue indexing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does the fail safe method rely on

A

Duplication of certain structural members. If one fails the other will take the load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the damage tolerance method

A

Requires an assessment to see if the damage sustained will lead in failure

This method is old and outdated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a further method of damage tolerance

A

By using crack limited joints. The joints will limit the spread of cracks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is fatigue known as

A

Fracturing after a series of cyclic loads, may be much less than the ultimate load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 3 categories of aircraft structure

A
  • Primary structure
  • Secondary structure
  • Tertiary structure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the characteristics of the primary structure

A

Critical load baring structure. Requires immediate repair if damaged as it can affect the structural integrity of the aircraft

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the characteristics of the secondary structure

A

Not load baring and the failure of a secondary structure would not affect the structural integrity of the aircraft

These consist of things like access panels and require repair as soon as possible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the characteristics of a tertiary structure

A

Not load baring and do not make up an integral part of the airframe. They consist of things like wing root fairings and landing gear fairings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 5 main structural units of an aircraft

A
  • The fuselage
  • The wings
  • The stabilisers
  • Flight control surfaces
  • The landing gears
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What main structural members make up an aircrafts structure

A

Stringers, frames, bulkheads, ribs, skin and other members

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How are structural members fixed together

A

With brackets, rivets, bolts, screws and nuts which add strength to the fuselage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are structural members designed to do

A

Carry a load or resist stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How is stress created

A

By the internal force of a substance which opposes or resists deformation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the 6 major types of stress that can effect aircraft structure

A
  • Tension
  • Compression
  • Torsion
  • Shear
  • Bending
  • Hoop stress
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Give the definition of tension

A

Stress that resits the forces trying to pull it apart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How do you calculate tensile strength

A

Divide the load (in pounds) with by the cross sectional area

The result is PSI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the definition of compression

A

Stress that resists a crushing force. Causes aircraft parts to be squeezed together

Usually measured in PSI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What type of stress is torsion

A

A twisting stress. For example when the rudder is deflected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is shear stress

A

Unaligned forces pushing one part of a body in one direction and another part in the opposite direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is bending stress

A

A combination between compression and tension.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

When an aircraft is pressurised what type of load is it under

A

Differential loading

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the two side effects of differential loading

A

One causes the compartment to stretch longitudinally and the other causes the circumference of the compartment to expand

This is known as hoop stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are the zones of the aircraft

A

Primary areas of aircraft such as the fuselage, wings and engines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

In what units do Boeing measure their zones

A

Imperial in inches

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are the reference lines called on Boeing aircraft

A

Body stations, body buttock lines and body water lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Where is the body station

A
  • A vertical plane at right angle to the body centreline

- Measured from a point in front of the aircraft (jig)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the abbreviation of body station

A

BS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What are the body buttock lines

A

Vertical planes parallel to the fuselage centreline

Body buttock line 0 is the body centreline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the abbreviation of Body Buttock line

A

BBL
For right - R BBL
For left - L BBL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What are the body water lines

A

Water lines are horizontal planes at right angles to the body stations and body buttock lines

Body waterline 0 is bellow the fuselage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Where is the reference line used for installation on components and equipment used by the manufacturer

A

Along the top surface of the floor beams

37
Q

On Boeing aircraft what are the wing coordinates used

A
  • The wing reference plane
  • Wing buttock lines
  • Wing stations
38
Q

On Boeing aircraft what are nacelle coordinates divided in to

A
  • Nacelle stations
  • Nacelle buttock lines
  • Nacelle water lines
39
Q

Where is nacelle station 0 on Boeing aircraft

A

In front of each forward engine mount

40
Q

On Boeing aircraft what are the horizontal stabiliser coordinates

A
  • The stabiliser chord plane
  • Buttock lines stations
  • Leading edge stations
  • Elevator stations
41
Q

What is the horizontal stabiliser reference plane

A

The plane through the leading edge and trailing edges of the stabiliser aerofoil

42
Q

On Boeing aircraft what coordinates is the vertical stabiliser split in to

A
  • Fin stations
  • Waterlines
  • Leading edge stations
  • Rudder stations
43
Q

How are the vertical and horizontal stabiliser stations identified on Airbus

A

They are called horizontal stab stations and vertical stab stations

44
Q

What zone is 100

A

Bottom of the fuselage

45
Q

What zone is 200

A

Top half of fuselage

46
Q

What zone is 300

A

Vertical and horizontal stabiliser

47
Q

What zone is 400

A

Power plant and struts

48
Q

What zone is 500

A

Left wing

49
Q

What zone is 600

A

Right wing

50
Q

What zone is 700

A

Landing gear and landing gear doors

51
Q

What zone is 800

A

Doors

52
Q

What is done to make a more accurate description of an object rather than just zone number

A

Major zones are broken down in to sub major zones for more precise location

53
Q

If two or more access panels are in the same zone what is done to identify each one

A

A letter is used after zone numbers

54
Q

How is the lower half of the pressurised fuselage drained

A

By using a system of valved drain holes

55
Q

How are fluids directed to the drain holes in the lower pressurised fuselage

A

Through a system of longitudinal and cross-drain paths through the stringers and frame shear clips

56
Q

What is used to prevent the loss of pressure through drain holes

A

Bilge- like valves are fitted

They are spring loaded

57
Q

What is the most basic form of lightning protection

A

The exterior almost all metal structure. It acts as a shield protecting internal areas from lightning and electrical systems from electromagnetic interference

58
Q

What must be done after a lightning strike has happened

A
  • General walk around and find out damaged area and discharge
  • If damage is found a detailed inspection is required and must be documented
59
Q

What two types of damage do lightning strikes usually result in

A

Direct damage - Surface is burned or melted or shows signs of metalic distortion at two or more points

Indirect damage - Large electrical transients on the wiring which may cause damage to the electrical systems equipment

60
Q

What type and size of mark will a lightning strike usually cause

A

A small circular melt mark approx 1/8 inch diameter

61
Q

What might other signs of lightning strike be

A

Burned or discoloured skin or rivets

62
Q

What are the lightning strike conditional inspection examines these areas

A
  • External surfaces
  • Static discharges
  • Fuel system valves
63
Q

What are the most likely places for lightning strikes to occur

A

Fuselage nose section and the aerofoil trailing edge tips

64
Q

What components could a high intensity lightning strike damage

A
  • Fuel valves
  • Generators
  • Power feeds
  • Electrical distribution systems
65
Q

Why are aircraft bonded

A
  • To minimise radio and radar interference
  • To eliminate fire hazard by preventing spark between two metallic components at different potentials
  • To minimise damage from lightning strikes
  • To provide a low resistance return path for single wire electrical systems
  • To aid effectiveness of shielding
66
Q

As long as protective coatings have been removed from components which bonding leads are attached what should the resistance not exceed when checked

A

A resistance no greater than 0.025 Ohms

67
Q

What conditions apply when installing grounds

A
  • Grounds must be separated AC, DC shields
  • There must be no more than 4 terminals on 1 stud
  • In a fuel vapour area dual grounds must be installed
68
Q

What is grounding

A

Grounding is the process of connecting systems and the shields of shielded cables to the aircraft metallic structure at pre-designated points

69
Q

What is a longeron

A

Main longitudinal member of a fuselage or nacelle

70
Q

What is a tie rod (tension rod)

A

Member taking a tensile load

71
Q

What is a strut

A

A member taking a compression load

72
Q

What is a spar

A

The main spanwise member of an aerofoil. Frequently consists of an upper and lower boom separated by a web

73
Q

What is a stringer

A

A stiffener which assists with sheet materials to carry loads along their length.

With integral construction they are machined or etched out of the skin panel

74
Q

What is ‘safe life’

A

The period in which It is considered that a failure of a component is extremely unlikely.

75
Q

What is a crack stopper

A

A reinforcing member usually placed at right angles to the path of an anticipated crack which will reduce the rate of further propagation

76
Q

What is static loading

A

Loads imposed on an aircraft when stationary

77
Q

What are the two types of fuselage construction

A
  • Truss Type

- Monocoque type

78
Q

What is truss type

A

Rigid framework made up from members such as beams, struts and bars to resist deformation by applied loads.

Usually light aircraft covered in fabric. Tubular fame welded

79
Q

What is the biggest problem with monocoque constructions

A

Since no bracing members are present the skin has to be strong enough to take all of the stress.

Strength the weight is the issue

80
Q

What is the main advantage of the semi monocoque construction

A

The structure can take a lot of stress or damage and still maintain enough strength to hold together

81
Q

What are floorboards constructed from

A

A honeycomb composite construction

82
Q

What is the empennage attachment

A

Similar to the wing box but for the horizontal and vertical stabilisers

83
Q

What is the purpose of engine nacelles

A

The contain the engine components and provide a streamlined enclosure

84
Q

When are bolts most commonly used on aircraft

A

When high strength is needed. If high strength is not needed then screws are used as a replacement

85
Q

What are the 3 main types of surface protection

A
  • Pretreatment
  • Paint coatings
  • Special coatings
86
Q

What would a pretreatment consist of

A
  • Increase corrosion resistance of the metal by chemical or electrochemical procedures
  • Give a good surface for paint coatings
87
Q

What would paint coatings consist of

A
  • Primer: Increases corrosion resistance

- Top coat: Adds to the surface protection and then provides good finishing qualities

88
Q

Why are special coatings used and what are used

A

They are used on materials or places that require extra or more intensive corrosion resistance

  • Type 1: Water repellant coating usually made from silicone free materials
  • Type 2: Heavy duty corrosion preventative compound, i.e. Greases available in various grades
89
Q

What is the purpose of surface cleaning

A

To remove dirt or oil for inspection and maintenance purposes