Chapter 4 - Aiframe Symmetry Flashcards
What parts are part of the primary and what happens if there is a failure?
Roof assembly supporting main rotor gear box (MRGB) and engine change unit(ECU), any failure causes structural collapse.
What are the parts that are part of secondary, and what can it fail?
Floors and stressed panels. It has a high reserve factor and is resistant to failure.
What parts are part of tertiary?
Doors and fairings. Non stressed panels.
What does the structure classification system aim for?
Aims to reduce the number of repair scheme references.
What are the factors affecting structural integrity?
Overstressing Operational hazards Corrosion Stress corrosion cracking Metal fatigue Damage tolerance Operator/maintainer damage
What are the four procedural errors?
Design error
Manufacturing error
Maintenance error
Supply error
What is airframe distortion caused by?
Ageing
Heavy landing
Over stressing
What are the effects of distortion?
Shaft alignment
Rotor thrust line
Rigging problems
Flying characteristics
What are the checks to determine distortion?
Rigging
Symmetry check
Triangulation
What terms are associated with airframe distortion?
Bending and twisting
What are longitudinal references?
They are given as stations, measured forward (F) and aft (A) of the vertical datum (station 0). The unit of measure can change between manufacturers I.e. Mm or inches. This is found on the x axis (datum).
What is a vertical reference?
These are measured above and below the horizontal datum (cabin floor level HO). Measurements below the HO reference are shown with a minus sign (-) before the datum I.e. ( -H1000). This reference is also known as the y datum.
What is the lateral reference?
Measured either side of the centre line.
What are the three structural classifications?
Primary, secondary and tertiary.
