11.2 - Basic Structures

Question 1

Where are the body stations measured from?

Answer 1

A point in front of the nose of the aircraft

Question 2

Major zones are divided into sub zones. how are these identified?

Answer 2

By the second digit of the number code

Question 3

How is the skin re-enforced in a semi monocoque airframe?

Answer 3

Longitudinal members(longerons, stringers), frames/formers

Question 4

On airbus aircraft, which kind of value has a position right of the center line?

Answer 4

negative Y value

Question 5

What is a body station?

Answer 5

A plane passing vertically through the fuselage from the referance point in front of the aircraft

Question 6

Which areas of the aircraft is most prone to lightning strikes?

Answer 6

Extremities (wing tips, fin tips etc)

Question 7

What types of loads are imposed on an aircraft when stationary?

Answer 7

Static loading

Question 8

What are the body coordinates called on an airbus?

Answer 8

Body Station
Body Buttock Line
Body Waterline

Question 9

Where are body waterlines measured from?

Answer 9

A parallel imaginary plane, body waterline 0, below aircraft fuselage

Question 10

What is meant by indirect lightning strike damage?

Answer 10

Damage to electrical systems

Question 11

Which types of loads are floor beams designed to carry?

Answer 11

Tensional loads

Question 12

What is the main function of the door mode selector lever?

Answer 12

To arm and disarm the emergency mechanism dependant upon which mode is selected

Question 13

What is the purpose of the vent hole in the inner pane of a cabin window?

Answer 13

To equalise the pressure between the two panes and the cabin

Question 14

What does the fuselage centre section provide?

Answer 14

It provides part of the cabin and the attachment structure for the wing centre box and the main landing gear

Question 15

What is the function of a fuselage stringer?

Answer 15

It gives shape to the fuselage shell and can carry bending, shear, torsion and cabin pressure loads

Question 16

What is the failsafe concept?

Answer 16

Duplication of certain parts to ensure that if one part fails, the other part assumes the load

Question 17

During a Symmetry check of a large aircraft, how are the measurements usually taken?

Answer 17

They suspend a plumb bob from the checkpoints and marking the floor. Then the measurements are taken from between the markings

Question 18

What are buttock lines?

Answer 18

Vertical planes parallel to the body (fuse). Buttock line 0 is the body centre line.

Question 19

What are wing stations?

Answer 19

The wing reference plane or wing stations extend left and right and are measured in either inches or millimetres from either a butt line reference point or from wing rib 1.

Question 20

What are drain valves for and how do they operate?

Answer 20

They are spring loaded to the open position when the cabin is depressurised, to drain condensation. They are “blige like” and close when the cabin pressurises

Question 21

How are the major zones numbered?

Answer 21

From 100 to 800

Question 22

What is zone number 400?

Answer 22

Powerplants

Question 23

What is zone number 700?

Answer 23

Landing gear and landing gear doors

Question 24

What zone are the left wing and what zone is the right wing?

Answer 24

500 and 600

Question 25

What is lightning strike direct damage?

Answer 25

Surface is burned, melted or shows sign of metal distortion. ##Footnote VISIBLE DAMAGE

Question 26

With direct lightning damage how are high intensity strikes measured?

Answer 26

Holes with a diameter of 6mm or more ##Footnote A regular strike is around 3mm

Question 27

What is the difference between bonding and grounding?

Answer 27

Bonding is the act of joining two electrical conductors together to ensure they carry the same electrical potential. Grounding is electrically connecting conductive objects to either a conductive structure or some other conductive return path

Question 28

What are the conditions of grounding?

Answer 28

They must be separated (AC, DC and shields) No more then 4 terminals on one stud Dual grounds must be installed in fuel vapour areas

Question 29

What is the difference between direct bonding and indirect bonding?

Answer 29

Direct: Exposing the mesh (ground plate) and the mounting equipment directing onto the conductive path Indirect: Exposing the mesh and installing a bonding wire and connector.

Question 30

If bonding is done correctly, measurements are not higher than…?

Answer 30

0.025 ohms

Question 31

What are struts?

Answer 31

Load bearing components to handle compression forces

Question 32

What are doublers?

Answer 32

Additional sections of materials used to reinforce areas of skin. Can also be used as “crack stoppers”

Question 33

What are ties?

Answer 33

Tie rods or tension members, used to handle tension forces

Question 34

What is the main issue with monocoque designs?

Answer 34

Strength/weight. Keeping enough strength while keeping weight within allowable limits. ##Footnote This is why we use semi monocoque, which uses stringers etc to transfer loads

Question 35

What is the main load bearing component in a wing construction?

Answer 35

Spars - Longitudinal members

Question 36

What is used to connect the spars?

Answer 36

Ribs - used to maintain the contour (aerodynamic shape) of the wing

Question 37

What is used to support spars?

Answer 37

Stringers and skin

Question 38

What is a truss type?

Answer 38

A rigid framework made up of members such as beams, struts and bars to resist deformation

Question 39

What are monocoque designs?

Answer 39

More common then semi, uses formers/frames and bulkheads to give shape, but the skin carries the primary stresses. ##Footnote Drawbacks include weight/strength. Needing a thicker skin, and if damage occurs to the fuse, it will be substantial.

Question 40

What are semi monocoque?

Answer 40

Uses longitudinal members such as longerons and stringers, to share the stresses. As the fuse can use manufacturers joints, to prevent damage from causing a total fuse collapse.