11.2 Damage Tolerance Concepts

Question 1

What must the aircraft be capable of when it comes to passengers?

Answer 1

Transporting them safely and be able to withstand all environmental conditions and stresses it will encounter

Question 2

What is the basic design philosophy of all aircraft manufacturers?

Answer 2

To produce the highest quality aircraft that is feasible, using the best design, materials and manufacturing techniques

Question 3

What testing is used to check if an aircraft structure is safe?

Answer 3

Full scale airframe testing, fatigue analysis and service experience

Question 4

What does the fail safe method rely on?

Answer 4

Structural members to ensure if one member fails the other will take the load of the failed part. The concept is one failure wouldn’t cause structural collapse

Question 5

What is a disadvantage of the fail safe concept?

Answer 5

It adds weight to the aircraft

Question 6

What is the safe life concept?

Answer 6

Based on a prediction of how long a structure can remain in service before reaching the point of fatigue damage

Question 7

What tests are carried out with safe life concepts?

Answer 7

Repeated static, dynamic load, and fatigue testing, where the airframe is taken to the point of fatigue damage and then on to catastrophic failure

Question 8

How can the safe life be calculated?

Answer 8

A number of cycles or operating hours

Question 9

The safe life allotted to the structure is around what of the maximum calculated cycles or operating hours?

Answer 9

1/3

Question 10

What is the damage tolerance concept

Answer 10

Requires an evaluation of the structure

Question 11

What tests are done with damage tolerance?

Answer 11

Repeated static and dynamic load tests

Question 12

What do safe life ensure?

Answer 12

These ensures that if considerable damage occurs, i.e., cracking or partial failure, it remains within the operational life of the aircraft

Question 13

What is the multiple load path concept?

Answer 13

In this method, large, heavy, and highly stressed members are avoided. Small members carry the loads, each supporting only a small percentage of the total. A failure of one load member will not degrade the structure as the other members will take over the support function

Question 14

What is crack limiting joints?

Answer 14

Parts of the structure are designed with special structural joints, which will limit the spread of cracks but will also ensure that these cracks can be detected during normal structural inspection cycles