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Groundschool : Module 1 > AGK Systems - Airframe design and material introduction > Flashcards

AGK Systems - Airframe design and material introduction Flashcards

1
Q

Certification Standard for small / large planes

A

CS-23 Smaller a/c

CS-25 Larger a/c

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2
Q

Minor Failure

A

Conditions may be Probable

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3
Q

Major Failure

A

Conditions must be no more frequent than remote

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4
Q

Hazardous Failre

A

Conditions must be no more frequent than Extremely Remote

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5
Q

Catastrophic Failure

A

Conditions must bear Extremely Improbable

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6
Q

Safe Life Concept

A

A/C which can comfortably sustain safe operations within its designed life span - its safe life

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7
Q

Safe life principles…

A

Explicitly stated design life

No catastrophic structural damage

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8
Q

Safe life may be measured in…

A

Flights Hours

Pressurisation Cycles

Landings or,

Calendar Duration

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9
Q

Fail safe concept

A

Multiple load paths

Designed to provide redundancy

Critical areas are built with fail safe multiple loads
~Ensures in one path fails, an alternate load path can carry all the loads through the duplicate structure

‘Where loss of components could lead to a/c loss

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10
Q

Damage tolerance concept

A

Some excess weight can be avoided by designing structures to be ‘Damage Tolerant’

These structures have crack-arresting features which limit extent to which a crack can spread

Surrounding paths carry all the load until the crack is detected

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11
Q

Redundancy concept

A

Is the duplication of vital components of systems for use in the event of a failure

Very useful tool for reducing probability of a major fault affecting a/c and passenger safety

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12
Q

Stress

Strain

A

Internal force per unit area
~Tension
~Compression
~Torsion
~Shear

Strain is the deformation of a component

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13
Q

Dynamic vs Static Loads

A

Dynamic
~Change quickly, rapid build up of load can cause serve stresses on materials

Static
~Build up slowly
~E.g. when a/c parked, its weight imposes load on wing spars from the landing gear

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14
Q

What is a Cyclic Load?

A

During flight loads can change and alternate rapidly

Components experience changes from compression to tension

Lead to Metal Fatigue

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15
Q

Why are the wind tanks used on t/o

A

Because there centre tanks have fresh fuel so by using wing tanks, you know the fuel is useable as yule just flown on it

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16
Q

What is the design load limit?

A

2.5g

Ultimate load 3.75g (1.5g x 2.5g)

17
Q

Fatigue Life

A

Based on cycles

Great mass will cause greater stress
~leads to fewer cycles before fatigue

Increase the weight by 1%, you increase the fatigue by 5%

18
Q

Operational Factors affecting Fatigue life

A

Max Ramp Mass (Taxiing/Towing)

Max Take-off Mass

Max Zero Fuel Mass

Max Landing Mass

19
Q

How to reduce Operational Factors effecting Fatigue Life

A

Reduce loads by:
~Avoiding coarse manoeuvring
~Avoiding Turbulence
~Not flying with excess fuel/payloads

These will increase the number of cycles before fatigue failure

20
Q

Corrosion Factors effecting Fatigue Life?

A

Corrosion destroys the smooth surface of metal

Tis exposes the metals underlying sharp crystalline structure

Ehen corrosion occurs, it provides a natural starting point for fatigue cracks

21
Q

What is Elasticity and Plasticity

A

Elasticity is the tendency of a material to return to its original shape after external load is removed

Plasticity is the tendency of a material to permanently deform when subjected to external load
~When. retrial is easily deformed, its said to have plastic properties and is susceptible to plastic deformation

22
Q

Reinforcing fibres can be made of?

A

Glass

Boron

Carbon

Aramid (aka Kevlar)

23
Q

Matrix is…

A

The material that supports the fibres, bonds them together and holds them in the desired orientation

Usually a type of thermosetting resin

24
Q

What’s a core (composite materials)

A

A material sometimes used in conjunction with fibre mats to create a strong sandwich-type laminate

25
Q

The stronger the component needs to be the … fibre mats are used

A

more

can make a component stronger one end than the other by using more/less fibre mats

26
Q

Composite Materials - Advantages

A

Fibres can be aligned to provide the best load qualities

Make complex shapes

Lighter

High Strength

High Stiffness

Resistant to corrosion

GOOD STRENGTH TO WEIGHT RATIO

27
Q

Composite Materials - Disadvantages

A

Hard to inspect for flaws

May absorb water, which can freeze and cause delamination

Can be expensive

Less damage tolerant

Requires immediate repair

Does not conduct electricity so requires electrical bonding

28
Q

What do carbon composite a/c have to avoid lightening strikes?

A

It has an metallic mesh

as the composite material has a low conductivity

29
Q

Corrosion defintion

A

Disintegration of an engineered material into its constituent atoms

30
Q

Types of Corrosion?

A

Oxidisation

Chemical reaction of metal with air causing a break down of metal surface

Electrolytic

Corrosion resulting from electric current between two metals coupled in an electrolytic environment

Stress Corrosion

Interaction of fatigue & corrosion that occurs in materials under high tensile loads

31
Q

What is Delamination?

A

Problem affecting composite structures

If structure is over stressed, the layers begin to separate

This process reduces the strength of the structure

Can be difficult to detect

32
Q

What process do you use to detect Delamination?

A

Ultrasound

Infrared Thermal Images

Radiography

33
Q

Two types of Maintenance

A

Hard Time Maintenance

On Condition Maintenance

34
Q

Hard Condition Maintenance

A

Definitive time limit on component

Failure preventative be removal from service before safe life expires

Service inspected on the last service before expiry

Time period based on:
Calendar time
Landings
Operating cycles
Flight hours
Block times

E.g. Landing Gear

35
Q

On Condition Maintenance

A

Periodic Inspection of component, checking against known standard or wear limit

Post check, the component either continues in service or is replaced

Components that fail the check must be overhauled

36
Q

What is Condition Monitoring?

A

Process of monitoring a parameter of condition in a a/c system (E.g. vibration, temp etc) in order to identify changes with could lead to faults

It allows maintenance to be scheduled as the a/c sends data to maintenance team
~Maintenance could be moved forward if it looks like a component will fail sooner than the actual maintenance time slot

Groundschool : Module 1 (38 decks)

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