Airframe Design and Materials

Question 1

CS 23 Certification?

Answer 1

Normal, utility aerobatic and commuter a/c.

Question 2

CS 25 Certification?

Answer 2

Applies to large aircraft

Question 3

Fail Safe

Answer 3

Multiple Load Paths, often duplicated allowing for redundancy within the structure. Can take the structure for limited amount of time.

Question 4

Disadvantage to Fail Safe

Answer 4

Heaver aircraft, increases cost and reduces performance/economy

Question 5

Damage Tolerance

Answer 5

• Crack arresting features
• Surrounding load paths designed to carry all the loads until faulty component detected and replaced

Question 6

Stress

Answer 6

Can’t see, leads to strain. Internal force per unit area inside a structural part as a result of external loads. Always present

Question 7

Strain

Answer 7

Deformation caused by the action of stress on a material. Can change shape of a component. Always present

Question 8

Signs of buckling/damage

Answer 8

• Wrinkling of the a/c skin
• Caused by excessive compression
• Loose/pulled rivets

Question 9

Static loads vs Dynamic Loads

Answer 9

Static Builds up over time slowly/remain constant, dynamic builds up and subsides quickly.

Question 10

Cyclic Loads

Answer 10

Loads experienced by an aircraft according to the flight phase. Alternating compression and tension can lead to metal fatigue.

Question 11

Vertical Loads

Answer 11

Caused by lift/weight

Question 12

A load equivalent to ______ of the most extreme forces expected in flight is applied to the wing structure which has to withstand it for __ seconds

Answer 12

150%, 3.

Question 13

Design limit load

Answer 13

Maximum anticipated load condition in flight

Question 14

Ultimate Load

Answer 14

1.5* DLL, known as the factor of safety.

Question 15

Maximum Structural Taxi Mass (MSTM) or Maximum Ramp Mass (MRM)

Answer 15

Maximum total mass at which the a/c can taxi

Question 16

Maximum Structural Take-off Mass (MSTOM)

Answer 16

In the name. Less than MRM.

Question 17

Max Zero Fuel Mass (MZFM)

Answer 17

Max mass of an a/c with no useable fuel.

Question 18

What is metal fatigue

Answer 18

Small cracks caused by many external factors

Question 19

A _% increase in weight leads to a _% increase in fatigue life consumption

Answer 19

1%, 5%

Question 19

A _% increase in weight leads to a _% increase in fatigue life consumption

Answer 19

1%, 5%

Question 20

Corrosion Types

Answer 20

Oxidisation, Electrolytic and Exposure to corrosive materials.

Question 21

Corrosion

Answer 21

The disintegration of an engineered material into its constituent atoms due to chemical reactions within it’s surroundings.

Question 22

Stress Corrosion

Answer 22

Caused by a combination of corrosive conditions and a steady tensile load

Question 23

Symptoms of corrosion

Answer 23

Pitting, discolouration.

Question 24

Hard Time Maintenance

Answer 24

Sets a definite time limit for individual components. Item is removed, overhauled or discarded. Based on landings, calendar, hours or cycles. For example some landing gear components.

Question 25

On condition maintenance

Answer 25

Allows for periodic inspection/testing of components against prescribed standards and limits. Part can fail or pass and is only used components which can be readily tested.