12.70.8(c) . fabric covering. 

12.70.8(b) . composite; 

12.70.8(a) . aluminium; 

12.70.8. Describe the indications of damage or failure of airframes constructed of;Sub Topic Syllabus Item 

12.70.6(c) . fabric covered. 

Structural integrity:
– lift and drag generated by the aircraft will be transmitted by the fabric through those areas where it is attached to the ribs and other parts of the airframe
– the suction force on the upper wing surface is borne by the fabric covering where it is unattached between the ribs
– at slower speed and lighter aircraft weights the lift required for flight can be generated with small pressure changes over the wings
– fabric applicationust therefore be restricted to use on relatively low never exceed speeds and low wing loadings
Indicated damage:-
– all seams and lapped joints must be inspected
– make sure surface tapes securely doped into place
– lacing cords checked for failure and tightness
– drain holes unobstructed
– no cuts, tears or other damage
– dope separation, whorls cracks and splits checked

12.70.6(b) . composite; 

Structural integrity
– behaves differently under normal loads than equivalent structures made of metal
– lighter than equivalent metal structure
– stiffer and less prone to fatigue and corrosion
– more resistant to damage from hail or small stones

Indicated damage:
– common casue of failoure is delamination
– dull areas or those with a whitish colour could indicate delamination
– slight bubble or depression
– External surface cracked or crazed
– areas of exposed fibres ie impact damage , lightning strike, areas fretted or abraded by rubbing toigether friction or subjection to high heat

12.70.6(a) . aluminium; 

Structural integrity
– this provides a significant portion of the structural strength of the aircraft
– designed to be fail-safe

Indicated damage
– designed and constructed in such a way that overstressing will result in gradual failure of a part of a structure and not a sudden and catastrophic failure of the whole thing
– indications of potential danage are: cracks in the skin, popped, loose or missing rivets, ontoward movement between airframe components, Also unusual buckling of the skin, or distortion or twisting of componenets of the airframe

12.70.6. Describe the precautions required to preserve the structural integrity of thefollowing airframes: 

12.70.4(b) . in the air, and state the function of spars and struts in opposing these loads. 

12.70.4(a) . on the ground;