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
