Module 11.2a Airframe structures

Question 1

What are the 5 stresses acting on an aircraft?

Answer 1

• Tension
• Shear
• Torsional
• Compressive
• Bending

Question 2

What are primary structural parts?

Answer 2

They have a critical role in aircraft integrity.

i.e. If they fail people die

Question 3

What are secondary structure parts?

Answer 3

All non-primary structural parts

Question 4

What is the final structure classification?

Answer 4

Tertiary

Question 5

What is hoop stress?

Answer 5

Hoop stress is the circumferential stress caused by the pressurisation of the aircraft on the fuselage

Question 6

The hoop stress will be _____ the value of the longitudinal stress

Answer 6

Twice

Question 7

What is fatigue caused by?

Answer 7

Cyclic or alternating loading

Question 8

What is the failsafe concept?

Answer 8

Duplication of certain structural parts so that if one break the other will bare the load carried by the other

Question 9

If a failure occurs on a failsafe part, is the part still failsafe?

Answer 9

No, not anymore

Question 10

What is the safe life of a component?

Answer 10

The safe life is the number of hours or cycles a part is safe for. This means that within this time period the part should not fail

Question 11

What are the five main structural units?

Answer 11

• Fuselage
• Wings
• Stabilisers
• Flight control surfaces
• Landing gears

Question 12

How does the zonal ident system work?

Answer 12

• 1st major zone
• 2nd sub major zone
• 3rd zone

Question 13

How are panels identified?

Answer 13

Panels have a 3 digit zonal ident followed by two characters

• 1st inbd to oubd, forward to aft, top to bottom
• 2nd Left to right

Question 14

What are body stations/ fuselage stations?

Answer 14

They are sections in the vertical plane that are perpendicular to the centre line

Question 15

What are buttock lines?

Answer 15

Buttock lines are lines in the vertical plane that run parallel to the centre line

Question 16

What are waterlines?

Answer 16

Waterlines are sections that run in the horizontal plane perpendicular to buttock and fuselage stations

Question 17

What are wing stations?

Answer 17

Sections in the vertical plane that run from leading edge to trailing and start at a reference buttock line or wing rib 1

Question 18

How are the horizontal and vertical stabilisers given wing station co-ordinates?

Answer 18

Equal to wing co-ordinates

Question 19

To prevent loss of air during pressurisation what valves are fitted to aircraft?

Answer 19

Bilge-like valves

Question 20

What position are bilge-like valves set too when the aircraft is depressurised?

Answer 20

Set too open

Question 21

Where is ventilation required?

Answer 21

Ventilation is required in areas where moisture or flammable fumes may build up

Question 22

How is fluid directed to drain valves?

Answer 22

Longitudinal and cross drain paths

Question 23

What are the two types of damage from lightning strikes?

Answer 23

Direct and indirect

Question 24

Why is bonding necessary?

Answer 24

For continuity throughout the aircraft and to ensure the is no difference in potential on the fuselage

Question 25

Why are electrical system onboard grounded to the structure?

Answer 25

So current returns on single wire systems, to stop damage if system is overloaded

Question 26

If bonding is correct what should the resistance measurement not exceed?

Answer 26

0.025 ohms

Question 27

What is major zone 100?

Answer 27

Lower half of fuselage

Question 28

What is major zone 200?

Answer 28

Upper half of fuselage

Question 29

What is major zone 300?

Answer 29

Empennage

Question 30

What is major zone 400?

Answer 30

Powerplants and struts

Question 31

What is major zone 500?

Answer 31

Left wing

Question 32

What is major zone 600?

Answer 32

Right wing

Question 33

What is major zone 700?

Answer 33

Landing gear + gear doors

Question 34

What is major zone 800?

Answer 34

Doors