11.2 A Airframe Structures Flashcards
What 3 provisions are made in the initial design phase?
. Fail safe load transfer
. Damage tolerance
. Fatigue indexing
What is the fail safe method?
Duplication of certain structural members to ensure that if one member failed, the other would take the load
What is the main disadvantage of fail safe?
Additional weight required
Explain what damage tolerance is
The structure is designed so that damage can be detected in normal inspections before failure occurs
What is the ultimate static load?
A value of load at which the material fractures
What are the three aircraft classifications?
. Primary structure
. Secondary structure
. Tertiary structure
Define primary structure
A critical load bearing structure that causes failure of structural integrity
Define secondary structure
Not a primary load carrying structure
And failure would not reduce the structural integrity, but need to be repaired asap.
Define tertiary structure
Not load carrying and does not form any integral portion
What is an aircraft 5 main structural points?
. Fuselage
. Wings
. Stabilisers
. Flight control surfaces
. Landing gears
What are the 6 stresses that affect an aircraft structure?
. Tension
. Compression
. Torsion
. Shear
. Bending
. Hoop stress
What causes hoop stress?
Due to pressurisation
. Compartment stretches longitudinally
. Circumference expands
What measurement do airbus vs boeing use in reference planes?
. Boeing = inches
. Airbus = cm/mm
What three aircraft axis do the body coordinates run along for AIRBUS.
. Vertical
. Lateral
. Longitudinal
What three body coordinates do BOEING use?
. Body station
. Body buttock lines
. Body waterlines
What is the definition of the body station?
A vertical plane at a right angle to the body centreline
What is the definition of the body buttock lines?
Vertical planes parallel to the body centreline
What is the defection of the body waterline?
Horizontal planes at a right angle to the body station and buttock lines
On a Boeing aircraft what are the 3 wing coordinates?
. Wing reference plane
. Wing buttock lines
. Wing stations
Where is the wing reference plane?
The same as the dihedral of the wing
Where is the wing buttock line?
A vertical plane at a right angle to the wing reference plane
Where is the wing station?
A vertical plane at a right angle to the wing reference plane and the rear spar
What am I describing… a horizontal plane, parallel to the body waterline
The fin waterline
Where a you find the rudder station?
At a right angle to the rudder hinge centreline
Why do we have major, sub major and zones?
To locate assemblies and sub assemblies, doors and panels
How many major zones are there?
8
Zone 100?
Lower half of fuselage
Zone 200?
Upper half fuselage
Zone 300?
Empennage
(Aft fuselage and horiz and vertical stab)
Zone 400?
Power plants and struts
Zone 500?
Left wing
Zone 600?
Right wing
Zone 700?
Landing gear and landing gear doors
Zone 800?
The doors
If I had a zone or 631, hay does the individual numbers mean?
600= major zone . right wing
30= sub major zone
1 = zone
How does aircraft lower drain valves work?
Spring load
When aircraft is depressurised = open
When pressurised = closed
What is the basic protection on the aircraft from a lightening strike?
All metal structure
Protects from EMF
What are the steps you must take when your aircraft is struck with lightening?
. General walk around
. If damage is found the a detailed inspection
What are the two types of lightening damage?
. Direct . Burns, distortion etc
. Indirect . Electrical damage
What is the size of a normal lightening burn?
1/8 inch
What is the size of a high intensity lightening burn?
1/4 inch
Do lightening strikes travel from the front to the back or back to the front?
Front to back
What is the purpose of bonding an aircraft?
Keep the aircraft and all components at the same electrical conductivity
And provides a low resistance return path
If binding is done correctly what should be the measurement of resistance?
No higher than 0.025 ohums
What is the process of grounding?
Connects single wire electrical systems to the aircraft metallic structure
(Direct line for electricity to escape safety)
When grounding how many terminals can be on one stud?
No more than 4
In vapour areas how many grounds just be installed?
2
How must grounds be separated?
By AC, DC and shields
