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Question 32-1 : The inner surface of a heated windscreen is of ? [ Questionnaire LAPL ]
Soft polycarbonate.
It is not the case for all aircraft, but most of the time, the inner surface of a heated windscreen is of soft polycarbonate or an equivalent product. it allows high resistance and very expandable seal, regarding temperature change constraints.
Question 32-2 : The purpose of stringers, used in fuselage construction, is to ?
Assist the skin withstand longitudinal compressive loads.
Question 32-3 : Significant torsion effects in a wing during flight can be caused by ?
Aileron deflection.
Question 32-4 : The two deformation modes that cause wing flutter are ?
Torsion and bending.
Flutter is a divergent oscillatory motion of a control surface caused by the interaction of aerodynamic forces, inertia forces and the stiffness of the structure it is a combination of bending and torsion of the structure... aero elastic coupling affects flutter characteristics.. the risk of flutter increases as ias increases.. if flutter occurs, ias should be reduced.. resistance to flutter increases with increasing wing stiffness.
Question 32-5 : One design method to avoid control surface flutter is ?
Ensuring correct mass distribution within the control surface.
Question 32-6 : A composite structural component consists of ?
A matrix and fibres.
Question 32-7 : The fuselage structure of a pressurised transport aeroplane is an example of a ?
Semi monocoque structure.
An egg is a good example of a monocoque structure. monocoque means 'single shell'...semi monocoque is a compromise which uses longerons stringers to take some of the strain. sandwich structure is a part of the 'shell' of an airframe..semi monocoque fuselage is the standard construction in nowadays. this has solved the problem with the thick of the sheet of the lining of the monocoque structure. this fuselage uses a thinner sheet by the use of structural members between. the members have the function of step up the union, and shape the fuselage.. 811.. 812. semi monocoque structure on a modern pressurised transport aeroplane.
Question 32-8 : When a wing bends downwards, aileron flutter might occur if the aileron deflects ?
Upwards, because the location of the aileron centre of gravity lies behind the hinge line.
Flutter is a dangerous phenomenon encountered in flexible structures subjected to aerodynamic forces. as the airspeed increases, there may be a point at which the structural damping is insufficient to damp out the motions which are increasing due to aerodynamic energy being added to the airfoil. this vibration can cause structural failure and therefore considering flutter characteristics is an essential part of designing an aircraft.. 813.if the cg is aft of the torsional axis, inertia causes the cg of the aileron to lag behind any movement of the axis caused by changes in lift. this lag can cause still further changes in incidence and hence lift making the matter worse..by having the cg on or forward of the hinge the torsion axis now uses the property of inertia to counter the effect.
Question 32-9 : A structure in which the skin takes all of the load is ?
A monocoque structure.
The monocoque design uses stressed skin to support almost all imposed loads. this structure can be very strong but cannot tolerate dents or deformation of the surface. this characteristic is easily demonstrated by a thin aluminum beverage can. you can exert considerable force to the ends of the can without causing any damage..however, if the side of the can is dented only slightly, the can will collapse easily. the true monocoque construction mainly consists of the skin, formers, and bulkheads. the formers and bulkheads provide shape for the fuselage... 657..since no bracing members are present, the skin must be strong enough to keep the fuselage rigid. thus, a significant problem involved in monocoque construction is maintaining enough strength while keeping the weight within allowable limits..due to the limitations of the monocoque design, a semi monocoque structure is used on many of today's aircraft.
Question 32-10 : A cantilever wing is ?
A wing attached to the fuselage at the wing root only.
A good example for a cantilever wing airplane is the cessna 177.. 807
Question 32-11 : A non cantilever wing is ?
A wing supported by braces or a strut connected to the fuselage.
Question 32-12 : A sandwich structural part ?
Consists of two thin sheets separated by a light core material.
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Question 32-13 : To achieve control flutter damping the balance mass must be located ?
In front of the control surface hinge.
Flutter is a dangerous phenomenon encountered in flexible structures subjected to aerodynamic forces. as the airspeed increases, there may be a point at which the structural damping is insufficient to damp out the motions which are increasing due to aerodynamic energy being added to the airfoil. this vibration can cause structural failure and therefore considering flutter characteristics is an essential part of designing an aircraft.. 813.to counteract this phenomenon, the control surface's cg must be as close as possible of the hinge the torsion axis.
Question 32-14 : Which of these statements concerning a sandwich structural part are correct or incorrect.i. the main function of the core material is to stabilise the covering sheets..ii. a sandwich structural part is well suited for absorbing concentrated loads. ?
I is correct, ii is incorrect.
Question 32-15 : When a wing bends upwards, aileron flutter might occur if the aileron deflects ?
Downwards, because the location of the aileron centre of gravity lies behind the hinge line.
Flutter is a dangerous phenomenon encountered in flexible structures subjected to aerodynamic forces. as the airspeed increases, there may be a point at which the structural damping is insufficient to damp out the motions which are increasing due to aerodynamic energy being added to the airfoil. this vibration can cause structural failure and therefore considering flutter characteristics is an essential part of designing an aircraft.. 813.if the cg is aft behind of the torsional axis, inertia causes the cg of the aileron to lag behind any movement of the axis caused by changes in lift. this lag can cause still further changes in incidence and hence lift making the matter worse..by having the cg on or forward of the hinge the torsion axis now uses the property of inertia to counter the effect.
Question 32-16 : Which of these statements regarding cockpit windows are correct or incorrect.i. on some aeroplanes the cockpit windows have an additional speed restriction, related to bird impact, when window heating is inoperative..ii. cockpit side windows are always provided with a de icing system. ?
I is correct, ii is incorrect.
The force from a bird impact increases with the square of the speed. a hot windshield is more pliable and less likely to shatter if it gets hit.. 815.bird strike example on a challenger...on modern aircraft example for the boeing 737 800 and max windows l1, r1 and l2, r2 have a conductive coating on the outer pane that permits electrical heating to prevent the build up of ice and fogging..for those models of the aircraft without electric heat to window l3 and r3, cabin air is circulated around the windshield to prevent fogging of the window.. 816
Question 32-17 : Which of these statements concerning a sandwich structural part are correct or incorrect. i. the main function of the core material is sound insulation.. ii. a sandwich structural part is well suited for absorbing concentrated loads. ?
I is incorrect, ii is incorrect.
Question 32-18 : Which of these statements regarding cockpit windows are correct or incorrect.i. cockpit windows never have an additional speed restriction, related to bird impact, when window heating is inoperative..ii. cockpit side windows are usually defogged only. ?
I is incorrect, ii is correct.
The force from a bird impact increases with the square of the speed. a hot windshield is more pliable and less likely to shatter if it gets hit.. 815.bird strike example on a challenger...on modern aircraft example for the boeing 737 800 and max windows l1, r1 and l2, r2 have a conductive coating on the outer pane that permits electrical heating to prevent the build up of ice and fogging..for those models of the aircraft without electric heat to window l3 and r3, cabin air is circulated around the windshield to prevent fogging of the window.. 816
Question 32-19 : Which of these statements about sandwich structural parts are correct or incorrect.i. a sandwich structural part consists of fibres and a resin..ii. a sandwich structural part is suitable for absorbing concentrated loads. ?
I is incorrect, ii is incorrect.
Question 32-20 : Which of these statements regarding cockpit windows are correct or incorrect.i cockpit windows never have an additional speed restriction, related to bird impact, when window heating is inoperative..ii cockpit side windows are always provided with a de icing system. ?
I is incorrect, ii is incorrect.
The force from a bird impact increases with the square of the speed. a hot windshield is more pliable and less likely to shatter if it gets hit.. 815.bird strike example on a challenger...on modern aircraft example for the boeing 737 800 and max windows l1, r1 and l2, r2 have a conductive coating on the outer pane that permits electrical heating to prevent the build up of ice and fogging..for those models of the aircraft without electric heat to window l3 and r3, cabin air is circulated around the windshield to prevent fogging of the window.. 816
Question 32-21 : Which of these statements regarding cockpit windows are correct or incorrect.i. on some aeroplanes the cockpit windows have an additional speed restriction, related to bird impact, when window heating is inoperative..ii. cockpit side windows are usually defogged only. ?
I is correct, ii is correct.
The force from a bird impact increases with the square of the speed. a hot windshield is more pliable and less likely to shatter if it gets hit.. 815.bird strike example on a challenger...on modern aircraft example for the boeing 737 800 and max windows l1, r1 and l2, r2 have a conductive coating on the outer pane that permits electrical heating to prevent the build up of ice and fogging..for those models of the aircraft without electric heat to window l3 and r3, cabin air is circulated around the windshield to prevent fogging of the window.. 816
Question 32-22 : Which of these statements about composite and metal structures are correct or incorrect.i. for a structural component with given dimensions composite materials enable a structural component's strength to be tailored to the direction of the load..ii. ?
I is correct, ii is correct.
Question 32-23 : Which of these statements about composite and metal structures are correct or incorrect.i. in a structural component with given dimensions constructed of composite materials, the strength is the same in all directions..ii. ?
I is incorrect, ii is incorrect.
For a structural component with given dimensions composite materials enable a structural component's strength to be tailored to the direction of the load..composite materials enable structures with higher strength/weight ratio than metal structures.
Question 32-24 : Which of these statements about composite and metal structures are correct or incorrect.i. for a structural component with given dimensions composite materials enable a structural component's strength to be tailored to the direction of the load..ii. ?
I is correct, ii is incorrect.
For a structural component with given dimensions composite materials enable a structural component's strength to be tailored to the direction of the load..composite materials enable structures with higher strength/weight ratio than metal structures.
Question 32-25 : What are the three elements of the fuselage structure of a large transport aeroplane ?
Skin, frames, stringers.
Question 32-26 : Which of these statements about composite and metal structures are correct or incorrect.i. in a structural component with given dimensions constructed of composite materials, the strength is the same in all directions..ii. ?
I is incorrect, ii is correct.
For a structural component with given dimensions composite materials enable a structural component's strength to be tailored to the direction of the load..composite materials enable structures with higher strength/weight ratio than metal structures.
Question 32-27 : A sandwich type structure is often used in aircraft because of its ?
Low mass and high stiffness.
Question 32-28 : A wing spar typically consists of ?
A web and girders.
A typical metal spar in a general aviation aircraft usually consists of a sheet aluminium spar web and girders, with 'l' or 't' shaped spar caps being welded or riveted to the top and bottom of the sheet to prevent buckling under applied loads.
Question 32-29 : A semi monocoque aircraft fuselage structure usually consists of ?
Skin, frames ,stringers.
Question 32-30 : A sandwich structural part is unsuitable for absorbing ?
Concentrated loads.
Question 32-31 : Which of these statements concerning a sandwich structural part are correct or incorrect.i. the main function of the core material is sound insulation..ii. a sandwich structural part is unsuitable for absorbing concentrated loads. ?
I is incorrect, ii is correct.
Question 32-32 : Which of these statements about sandwich structural parts are correct or incorrect.i. a sandwich structural part consists of two thin sheets enclosing a light core material..ii. a sandwich structural part is suitable for absorbing concentrated loads. ?
I is correct, ii is incorrect.
Question 32-33 : Which of these statements about sandwich structural parts are correct or incorrect.i. a sandwich structural part consists of fibres and a resin..ii. a sandwich structural part is not suitable for absorbing concentrated loads. ?
I is incorrect, ii is correct.
.composite materials, such as sandwich structural parts, are made from fibres generally embedded in epoxy resin, covered with a skin of aluminium, kevlar or nomex..sandwich structural parts need additional provisions to carry concentrated loads.
Question 32-34 : The function of ribs in a wing is to ?
Give the wing the desired aerodynamic shape.
Question 32-35 : The pressurisation load on the skin of a fuselage is ?
Tension.
Question 32-36 : When the wing skin is not able to carry loads, the structural elements of the wing, which carry the bending moment, are ?
The spars.
The spars are able to carry the upward resulting from the wing lift force that supports the fuselage in flight and downward whilst stationary on the ground due to the weight of the structure, fuel carried in the wings, and wing mounted engines if used bending moments.
Question 32-37 : Which of these statements about the wing structure is correct ?
A torsion box is formed by wing spars, ribs and wing skin reinforced by stringers.
Question 32-38 : The purpose of bonding the metallic parts of an aircraft is to.1 prevent electrolytic corrosion between mating surfaces of similar metals.2 ensure zero voltage difference between aircraft components.3 isolate all components electrically.4 provide a single earth for electrical devices. ?
2, 4.
.bonding is the electrical interconnection of metallic aircraft parts normally at earth potential for the safe distribution of electrical charges and currents..bonding provides a means of protection against charges as a result of the build up of precipitation, static and electrostatic induction as a result of lightning strikes so that the safety of the aircraft or its occupants is not endangered..bonding reduces the possibility of electric shock from the electrical supply system, reduces interference with the functioning of essential services e.g. radio communications and navigational aids and provides a low resistance electrical return path for electric current in earth return systems.
Question 32-39 : Which sequence correctly places the fuselage shapes illustrated in order of decreasing structural strength. 818 ?
2, 3, 4, 1.
N°1 is clearly the weakest, and would only be used on an unpressurised aircraft twin otter for example..n°2 is geometrically the strongest from a pressurisation point of view, as the hoop stresses can be uniform on the whole cross section...n°3 'double bubble' type, where two circles intersect, connected via a floor not the best choice but clearly better than n°4...n°4 the pressurization constraints will not be optimal on an oval format...this question also exists with the statement 'from the following fuselage profile, sort them from the worst to the best one concerning the pressurization '.answer 1, 4, 3, 2
Question 32-40 : Hydraulic fluids must have the following characteristics..1 thermal stability.2 low emulsifying characteristics.3 corrosion resistance.4 good resistance to combustion.5 high compressibility.6 high volatility.7 high viscosity..the combination regrouping all the correct statements is ?
1, 2, 3 and 4.
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