Module 11.2a Airframe structures Flashcards
What are the 5 stresses acting on an aircraft?
- Tension
- Shear
- Torsional
- Compressive
- Bending
What are primary structural parts?
They have a critical role in aircraft integrity.
i.e. If they fail people die
What are secondary structure parts?
All non-primary structural parts
What is the final structure classification?
Tertiary
What is hoop stress?
Hoop stress is the circumferential stress caused by the pressurisation of the aircraft on the fuselage
The hoop stress will be _____ the value of the longitudinal stress
Twice
What is fatigue caused by?
Cyclic or alternating loading
What is the failsafe concept?
Duplication of certain structural parts so that if one break the other will bare the load carried by the other
If a failure occurs on a failsafe part, is the part still failsafe?
No, not anymore
What is the safe life of a component?
The safe life is the number of hours or cycles a part is safe for. This means that within this time period the part should not fail
What are the five main structural units?
- Fuselage
- Wings
- Stabilisers
- Flight control surfaces
- Landing gears
How does the zonal ident system work?
- 1st major zone
- 2nd sub major zone
- 3rd zone
How are panels identified?
Panels have a 3 digit zonal ident followed by two characters
- 1st inbd to oubd, forward to aft, top to bottom
- 2nd Left to right
What are body stations/ fuselage stations?
They are sections in the vertical plane that are perpendicular to the centre line
What are buttock lines?
Buttock lines are lines in the vertical plane that run parallel to the centre line
What are waterlines?
Waterlines are sections that run in the horizontal plane perpendicular to buttock and fuselage stations
What are wing stations?
Sections in the vertical plane that run from leading edge to trailing and start at a reference buttock line or wing rib 1
How are the horizontal and vertical stabilisers given wing station co-ordinates?
Equal to wing co-ordinates
To prevent loss of air during pressurisation what valves are fitted to aircraft?
Bilge-like valves
What position are bilge-like valves set too when the aircraft is depressurised?
Set too open
Where is ventilation required?
Ventilation is required in areas where moisture or flammable fumes may build up
How is fluid directed to drain valves?
Longitudinal and cross drain paths
What are the two types of damage from lightning strikes?
Direct and indirect
Why is bonding necessary?
For continuity throughout the aircraft and to ensure the is no difference in potential on the fuselage
