11.2 Aircraft Structures - General Concepts Flashcards
when changing a component, what is the responsibility of the engineer?
to inspect the surrounding area for corrosion, fretting, cracking, pitting among others
what are aircraft structures designed to carry?
load or resist stress
what must every part of the aircraft be planned to carry?
loads imposed upon it
what type of analysis is completed to determine loads on aircraft structure?
stress analysis
what 3 types of structural design philosophies is there?
- failsafe
- damage tolerance
- fatigue
what does the failsafe method rely on?
duplication of certain structural members
is the failsafe method purely for structural members?
no. (can be used in cabin windows for example)
what is the advantage of damage tolerance over failsafe?
damage can be detected during normal inspections before failure
how does the damage tolerance method differ from failsafe?
failure of one load member will not degrade structure, loads will transfer to other areas of the member
fracturing from a series of cyclic loading is known as what?
fatigue
what is fatigue?
ultimate static load the material can take
what is done to verify the fatigue life of aircraft structure?
fatigue testing, subjected to various loads. accurate prediction of life
what 3 types of structure is there?
- primary
- secondary
- tertiary
what are the definitions for the 3 types of structure?
- primary = critical load-bearing structure, may result in injury or death
- secondary = not primary load bearing, failure wouldn’t reduce structural integrity,
- tertiary = not load carrying members, don’t form an integral portion of the airframe
what are the 5 main structural units?
- fuselage
- wings
- stabilisers
- flight control surfaces
- landing gear
what are airframe components made up of? [5]
- stringers
- ribs
- frames
- bulkheads
- skins and others
what 6 types of strucural stresses are there?
- tension
- compression
- torsion
- shear
- bending
- hoop stress
what is hoop stress?
due to presurisation of the aircraft, stretching of aircraft and expansion of the circumference of skin
what is a body station?
vertical plane at right angle to the aircraft centre line
where is body station measured from?
predetermined position infront of the aircraft nose
what is the body buttock lines? and where do you look to determine this?
from the rear of the aircraft
parallel to the aircraft centre line, LBBL and RBBL
what is body water lines?
horizontal plane at the right angle to body station
Where is the body waterline measured from?
From the underneath the fuselage or the floor from inside the fuselage
What coordinates can be found on the wing? [3]
- Wing reference plane
- Wing buttock lines
- Wing stations
How is the wing buttock line plane viewed?
Vertical plane at a right angle to the wing reference plane
How is wing station viewed?
At a right angle to the rear spar and wing reference plane
What coordinates are found on the nacelles? [3]
- Nacelle stations
- Nacelle buttock lines
- Nacelle water lines
How is nacelle station viewed?
Vertical plane at a right angle to nacelle centreline
Where is nacelle station zero found on Boeing aircraft?
In front of the forward engine mount
What nacelle buttock line relative to?
Wing buttock line
What are nacelle waterlines?
Parallel to wing reference plane
Where is nacelle water line zero?
Below the nacelle
What coordinates are found on the horizontal stabiliser? [4]
- Stabiliser chord plane
- Buttock line stations
- Leading edge stations
- Elevator stations
What other name is there for stabiliser chord plane?
Horizontal stabiliser reference plane