AGK Systems Flashcards
Minor failure conditions ?
May be probable
Major failure conditions ?
Must be no more frequent than remote
Hazardous failure conditions ?
Must be no more frequent than extremely remote
Catastrophic failure conditions ?
Must be extremely improbable
Safe life concept ?
Requires structures to have an explicitly stated lifespan within which no catastrophic structural damage may occur under safe operation
Safe-life concept can be measured in ?
Flight hours
Pressurisation cycles
Landings
Calendar duration
Fail safe design ?
Critical areas have multiple load paths, designed to provide redundancy. This ensures if one fails an alternate path can carry all load through duplicate.
Fail safe design examples
Wing spar attachments
Tail plane attachment
Engine fittings
Cabin windows
Fail safe design disadvantages ?
Weight penalty consumption
Corrosion
Fatigue
Damaged tolerance design?
Some excess weight can be avoided if the are damage tolerant, these structures have crack arresting features.
What is load ?
An external force applied to a component that causes stress, which leads to deformation, know as strain
4 main stress types ?
Tension
Torsion
Compression
Shear
Dynamic loads are ?
Imposed by manoeuvring and can change very fast.
Rapid build up can cause severe stresses on materials.
Static loads … ?
Build up slowly or remain constant
Cyclic loads ?
During flight loads change and alternate rapidly, components experience compression and tension changes.
Can cause metal fatigue which can lead to structural failure
Overstress ?
Can lead to structural failure and any suspected OS must be investigated.
Areas prone to stress ?
Spar lines
Wing horizontal and vertical attachments
Roots
A/C skin
Load limit on transport A/C
2.5 g
Ultimate load limit is (+50%)
So 3.75g
Risk of fatigue increases with ?
Corrosion
High number of flight cycles
Hard manoeuvring
Poor maintenance practices
How is fatigue detected ?
Visual inspection during walk around
Corrosive conditions and steady tensile load can produce metal fatigue, also known as ?
Stress corrosion
Max ramp mass ?
Max mass authorised for manoeuvring on the ground
Max take off mass ?
Mass at which the pilot is allowed to take off
Max zero fuel mass ?
Mass of A/C and all it’s contents excluding the weight of useable fuel onboard