11.2 Flashcards
(38 cards)
What defines a primary structure?
If damaged or broken it could cause
- loss of control of the aircraft
- catastrophic structural collapse
- harm to occupants
- failure of the power unit
- unintended operation
- incapability to perform a service
What do (PSEs) principle structural elements do?
Bear the loads associated with flight
What defines a secondary structure?
Any non primary structure which poses intrinsic structural significance
What is tertiary structure?
All remaining framework under light stresses
What is a fail safe method?
A component which has a “backup” component or shares the load
What is the safe life concept?
How long the component can remain safely in service
What are the ATA zones
100 - lower fuselage
200 - upper fuselage
300 - empennage
400 - power plant and struts
500 - left wing
600 - right wing
700 - landing gear and their doors
800 - doors
How are sub zero zones denoted?
The third digit
How are co ordinates categorised?
Body, fuselage, water, and butt lines
How is the body station/ fuselage station shown and measured?
Right angle planes measured from a point in front of the nose
How are buttock lines shown and measured?
Measured from 0 at the midpoint parallel to the fuselage
How are water lines measured?
Right angle to body stations and buttock lines horizontal with the centre being 0
How are wing lines measured/ placed?
Measured from butt lines or wing rib one parallel to the fuselage
What is hoop stress?
Circumferential tensile stress from pressurisation
What is strain?
The ratio of the amount of deformation of a material caused by stress
What is one Damage tolerance concept to minimise damage to large structural components?
Multiple path loads which put force through multiple smaller components
How is pressure loss prevented on drain holes?
Bilge like valves which are open on the ground and closed in the air
When is ventilation required?
When any vapour can build up
What are the fuselage members?
- frame
- longeron
- skin
-stringer
What are frames/ formers?
Lateral fuselage or nacelle members giving a cross sectional shape often circular
What was developed in terms of structure to limit strength to weight ratio issues?
Semi monocoque design with stringers etc to transfer weight
What are the uses of bulkheads?
Give shape to fuselage and close of or partition an area
What are longerons?
Main longitudinal members they take on primary bending loads supplemented by stringers
What are stringers?
Smaller and lighter than longerons they stiffen sheet metals mainly used for giving shape they are clipped or cleated in
