11.2

Question 1

What defines a primary structure?

Answer 1

If damaged or broken it could cause
- loss of control of the aircraft
- catastrophic structural collapse
- harm to occupants
- failure of the power unit
- unintended operation
- incapability to perform a service

Question 2

What do (PSEs) principle structural elements do?

Answer 2

Bear the loads associated with flight

Question 3

What defines a secondary structure?

Answer 3

Any non primary structure which poses intrinsic structural significance

Question 4

What is tertiary structure?

Answer 4

All remaining framework under light stresses

Question 5

What is a fail safe method?

Answer 5

A component which has a “backup” component or shares the load

Question 6

What is the safe life concept?

Answer 6

How long the component can remain safely in service

Question 7

What are the ATA zones

Answer 7

100 - lower fuselage
200 - upper fuselage
300 - empennage
400 - power plant and struts
500 - left wing
600 - right wing
700 - landing gear and their doors
800 - doors

Question 8

How are sub zero zones denoted?

Answer 8

The third digit

Question 9

How are co ordinates categorised?

Answer 9

Body, fuselage, water, and butt lines

Question 10

How is the body station/ fuselage station shown and measured?

Answer 10

Right angle planes measured from a point in front of the nose

Question 11

How are buttock lines shown and measured?

Answer 11

Measured from 0 at the midpoint parallel to the fuselage

Question 12

How are water lines measured?

Answer 12

Right angle to body stations and buttock lines horizontal with the centre being 0

Question 13

How are wing lines measured/ placed?

Answer 13

Measured from butt lines or wing rib one parallel to the fuselage

Question 14

What is hoop stress?

Answer 14

Circumferential tensile stress from pressurisation

Question 15

What is strain?

Answer 15

The ratio of the amount of deformation of a material caused by stress

Question 16

What is one Damage tolerance concept to minimise damage to large structural components?

Answer 16

Multiple path loads which put force through multiple smaller components

Question 17

How is pressure loss prevented on drain holes?

Answer 17

Bilge like valves which are open on the ground and closed in the air

Question 18

When is ventilation required?

Answer 18

When any vapour can build up

Question 19

What are the fuselage members?

Answer 19

• frame
• longeron
• skin
  -stringer

Question 20

What are frames/ formers?

Answer 20

Lateral fuselage or nacelle members giving a cross sectional shape often circular

Question 21

What was developed in terms of structure to limit strength to weight ratio issues?

Answer 21

Semi monocoque design with stringers etc to transfer weight

Question 22

What are the uses of bulkheads?

Answer 22

Give shape to fuselage and close of or partition an area

Question 23

What are longerons?

Answer 23

Main longitudinal members they take on primary bending loads supplemented by stringers

Question 24

What are stringers?

Answer 24

Smaller and lighter than longerons they stiffen sheet metals mainly used for giving shape they are clipped or cleated in

Question 25

What are doublers?

Answer 25

Doubled skin to increase strength found around apertures eg windows and doors

Question 26

What else are doublers made for?

Answer 26

Crack stoppers placed at right angles to prevent potential cracks or stop the advance of one

Question 27

What are struts?

Answer 27

Load bearing components that primarily handle compression typically transferring force from one part of the fuselage to another

Question 28

What are ties?

Answer 28

AKA tie rods/ tension members
Handle tension forces in fuselage often in addition to struts

Question 29

What are beams or floor members constructed of?

Answer 29

Honey comb composite

Question 30

How are wings constructed?

Answer 30

Spars reinforced with ribs covered with stressed skin

Question 31

What are the types of fuselage construction?

Answer 31

Truss, monocoque, semi monocoque

Question 32

How is truss type constructed?

Answer 32

Members such as beams, struts and bars often covered with fabric

Question 33

How is monocoque constructed?

Answer 33

Skin carries primary stress with formers

Question 34

How is semi monocoque constructed?

Answer 34

It is a stressed skin structure reinforced by longitudinal members and formers primarily made with aluminium

Question 35

What is the main advantage of semi monocoque?

Answer 35

It can sustain damage and not fail

Question 36

What is the maximum bonding resistance that should be measured on bonding leads?

Answer 36

0.025 ohms

Question 37

When grounding how many terminals can there be per stud?

Answer 37

No more than 4

Question 38

What must be installed in fuel vapour areas in terms of bonding?

Answer 38

Dual grounds