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Validation > Marking : Which of these statements about structural design principles are correct or ?

Question 17-1 : I is incorrect ii is incorrect i is correct ii is correct i is correct ii is incorrect i is incorrect ii is correct

In a 'fail safe' construction the components were designed in a way that the loads are shared among adjacent components.if one component fails the adjacent components take up the load for a limited period of time enough to allow the detection at the next periodic inspection.the philosophy of 'fail safe' is to anticipate a possible failure with a minimum of harm .in a 'safe life' construction the components are given for a time period and/or number of cycles x landings x engine starts and must be removed from service when the appropriate criteria are met.the 'safe life' design technique is employed in critical systems which are either very difficult to repair or may cause severe damage to life and property.statement ii is incorrect because you can not guarantee that a part will definitely not will never fail within its calculated number of cycles or its period

Which of these statements about structural design principles are correct or ?

Question 17-2 : I is correct ii is correct i is correct ii is incorrect i is incorrect ii is incorrect i is incorrect ii is correct

Damage tolerant components will not have a specfied life continued operation is based on frequent inspections and takes cracking of the structure into account.in a 'safe life' construction the components are given for a time period and/or number of cycles x landings x engine starts and must be removed from service when the appropriate criteria are met exemple 121 i is correct, ii is correct.i is correct, ii is correct.

Which of these statements about structural design principles are correct or ?

Question 17-3 : I is incorrect ii is correct i is correct ii is incorrect i is incorrect ii is incorrect i is correct ii is correct

Damage tolerant components will not have a specfied life continued operation is based on frequent inspections and takes cracking of the structure into account.in a 'safe life' construction the components are given for a time period and/or number of cycles x landings x engine starts and must be removed from service when the appropriate criteria are met exemple 125 i is incorrect, ii is correct.i is incorrect, ii is correct.

Which of these statements about structural design principles are correct or ?

Question 17-4 : I is incorrect ii is correct i is incorrect ii is incorrect i is correct ii is incorrect i is correct ii is correct

In a 'fail safe' construction the components were designed in a way that the loads are shared among adjacent components .if one component fails the adjacent components take up the load for a limited period of time enough to allow the detection at the next periodic inspection .the philosophy of 'fail safe' is to anticipate a possible failure with a minimum of harm.in a 'safe life' construction the components are given for a time period and/or number of cycles x landings x engine starts and must be removed from service when the appropriate criteria are met .the 'safe life' design technique is employed in critical systems which are either very difficult to repair or may cause severe damage to life and property.statement i is incorrect because you can not guarantee that a part will definitely not will never fail exemple 129 i is incorrect, ii is correct.i is incorrect, ii is correct.

According jar/cs 25 the worst effect of a minor failure on the occupants of an ?

Question 17-5 : Physical discomfort inconvenience serious or fatal injury to a small number of passengers or cabin crew physical distress possibly including injuries

. certification specifications for large aeroplanes cs 25 book 2 acceptable means of compliance .click here see table on last page .pdf652 exemple 133 physical discomfort.physical discomfort.

According jar/cs 25 the worst effect of a major failure on the occupants of an ?

Question 17-6 : Physical distress possibly including injuries inconvenience serious or fatal injury to a small number of passengers or cabin crew physical discomfort

. certification specifications for large aeroplanes cs 25 book 2 acceptable means of compliance .click here see table on last page .pdf652 exemple 137 physical distress, possibly including injuries.physical distress, possibly including injuries.

According jar/cs 25 the worst effect of a catastrophic failure on the aeroplane ?

Question 17-7 : Hull loss large reduction in functional capabilities or safety margins significant reduction in functional capabilities or safety margins slight reduction in functional capabilities or safety margins

. certification specifications for large aeroplanes cs 25 book 2 acceptable means of compliance .click here see table on last page .pdf652 exemple 141 hull loss.hull loss.

According jar/cs 25 the allowable quantitative average failure probability per ?

Question 17-8 : Between 10^ 7 and 10^ 9 extremely remote less than 10^ 9 extremely improbable between 10^ 5 and 10^ 7 remote between 10^ 3 and 10^ 5 probable

. certification specifications for large aeroplanes cs 25 book 2 acceptable means of compliance .click here see table on last page .pdf652 exemple 145 between 10^ -7 and 10^ -9. (extremely remote)between 10^ -7 and 10^ -9. (extremely remote)

According jar/cs 25 the worst effect of a minor failure on the flight crew ?

Question 17-9 : A slight increase in workload no effect on flight crew physical distress or excessive workload impairs ability to perform tasks physical discomfort or a significant increase in workload

. certification specifications for large aeroplanes cs 25 book 2 acceptable means of compliance .click here see table on last page .pdf652 exemple 149 a slight increase in workload.a slight increase in workload.

According jar/cs 25 the worst effect of a major failure on the flight crew ?

Question 17-10 : Physical discomfort or a significant increase in workload no effect on flight crew physical distress or excessive workload impairs ability to perform tasks a slight increase in workload

. certification specifications for large aeroplanes cs 25 book 2 acceptable means of compliance .click here see table on last page .pdf652 exemple 153 physical discomfort or a significant increase in workload.physical discomfort or a significant increase in workload.

According jar/cs 25 the worst effect of a minor failure on the aeroplane could ?

Question 17-11 : Slight reduction in functional capabilities or safety margins no effect on operational capabilities or safety large reduction in functional capabilities or safety margins significant reduction in functional capabilities or safety margins

. certification specifications for large aeroplanes cs 25 book 2 acceptable means of compliance .click here see table on last page .pdf652 exemple 157 slight reduction in functional capabilities or safety margins.slight reduction in functional capabilities or safety margins.

According jar/cs 25 the worst effect of a catastrophic failure on the flight ?

Question 17-12 : Fatalities or incapacitation physical distress or excessive workload impairs ability to perform tasks physical discomfort or a significant increase in workload a slight increase in workload

. certification specifications for large aeroplanes cs 25 book 2 acceptable means of compliance .click here see table on last page .pdf652 exemple 161 fatalities or incapacitation.fatalities or incapacitation.

The principle of damage tolerance in structural design of an aircraft is based ?

Question 17-13 : Capability to withstand a certain amount of weakening of the structure without catastrophic failure replacement of parts after a given number of cycles or hours of use fact that there is no need to inspect the structure monitoring of critical parameters and the replacement of parts if a limit value is exceeded

Damage tolerant components will not have a specified life continued operation is based on frequent inspections and takes cracking of the structure into account exemple 165 capability to withstand a certain amount of weakening of the structure without catastrophic failure.capability to withstand a certain amount of weakening of the structure without catastrophic failure.

The principle of 'on condition maintenance' is based on the ?

Question 17-14 : Monitoring of critical parameters and the replacement of parts if a limit value is exceeded replacement of parts after a given number of cycles or hours of use redundancy of the structure or equipment capability to withstand a certain amount of weakening of the structure without catastrophic failure

On condition maintenance is a preventative process in which an item is monitored either continuously or at specified periods the item's performance is compared to an appropriate standard in order to determine if it can continue in service exemple 169 monitoring of critical parameters and the replacement of parts if a limit value is exceeded.monitoring of critical parameters and the replacement of parts if a limit value is exceeded.

The principle of 'fail safe' design of an aircraft is based on the ?

Question 17-15 : Redundancy of the structure or equipment replacement of parts after a given number of cycles or hours of use capability to withstand a certain amount of weakening of the structure without catastrophic failure monitoring of critical parameters and the replacement of parts if a limit value is exceeded

In a 'fail safe' construction the components were designed in a way that the loads are shared among adjacent components .if one component fails the adjacent components take up the load for a limited period of time enough to allow the detection at the next periodic inspection .the philosophy of 'fail safe' is to anticipate a possible failure with a minimum of harm exemple 173 redundancy of the structure or equipment.redundancy of the structure or equipment.

According jar/cs 25 the worst effect of a catastrophic failure on the occupants ?

Question 17-16 : Multiple fatalities serious or fatal injury to a small number of passengers or cabin crew physical distress possibly including injuries physical discomfort

. certification specifications for large aeroplanes cs 25 book 2 acceptable means of compliance .click here see table on last page .pdf652 exemple 177 multiple fatalities.multiple fatalities.

A safe life aircraft structural component ?

Question 17-17 : May be used during a declared number of cycles or flight hours should have enough strength during the whole lifetime of an aircraft is so strong that it never will fail during a declared time period has parallel load paths

In a 'safe life' construction the components are given for a time period and/or number of cycles x landings x engine starts and must be removed from service when the appropriate criteria are met .the 'safe life' design technique is employed in critical systems which are either very difficult to repair or may cause severe damage to life and property

Whilst stationary on the ground in a hangar the most important loads on a ?

Question 17-18 : Tension in the upper surface compression in the lower surface tension in both the upper and the lower surfaces compression in the upper surface tension in the lower surface compression in both the upper and the lower surfaces

Howarthson .stationary on the ground the wings are drooping under gravity stretching the top skin and compressing the bottom skin in flight lift is pulling the wings up stretching the bottom and compressing the top exemple 185 tension in the upper surface, compression in the lower surface.tension in the upper surface, compression in the lower surface.

In straight and level flight the most important loads on a cantilever wing are ?

Question 17-19 : Compression in the upper surface tension in the lower surface tension in the upper surface compression in the lower surface compression in both the upper and the lower surfaces tension in both the upper and the lower surfaces

The most important loads on a cantilever wing in flight are compression in the upper surface tension in the lower surface. 809..on the ground it's the opposite

Define the term 'fatigue' ?

Question 17-20 : If a material is continually loaded and unloaded it will eventually break even though the load remains the same a one off loading that breaks the material a loading on the material but it returns fully to its former state when the load is removed the material suffers progressively more permanent damage each time that it is loaded and unloaded

The life of an airframe is limited by fatigue caused by the load cycles imposed during takeoff landing and pressurisation this life has been calculated over the years by using different design philosophies these being 'safe life' 'fail safe' and 'damage tolerant' exemple 193 if a material is continually loaded and unloaded it will eventually break even though the load remains the same.if a material is continually loaded and unloaded it will eventually break even though the load remains the same.

Which of these statements about structural design principles are correct or ?

Question 17-21 : I is correct ii is incorrect i is incorrect ii is incorrect i is correct ii is correct i is incorrect ii is correct

.in a 'fail safe' construction the components were designed in a way that the loads are shared among adjacent components .if one component fails the adjacent components take up the load for a limited period of time enough to allow the detection at the next periodic inspection .the philosophy of 'fail safe' is to anticipate a possible failure with a minimum of harm .in a 'safe life' construction the components are given for a time period and/or number of cycles x landings x engine starts and must be removed from service when the appropriate criteria are met .the 'safe life' design technique is employed in critical systems which are either very difficult to repair or may cause severe damage to life and property.statement ii is incorrect because you can not guarantee that a part will definitely not will never fail within its calculated number of cycles or its period exemple 197 i is correct, ii is incorrect.i is correct, ii is incorrect.

At point 1 the load moment is . 2760 ?

Question 17-22 : Tension shear compression torsion

exemple 201 tension.tension.

On modern transport aircraft cockpit windows are protected against icing by ?

Question 17-23 : Electric heating anti icing fluid vinyl coating rain repellent system

.on boeing 777 for example the windshield consists of three plies of glass with exterior surface anti icing and exterior and interior surface anti fogging protection the plies are comprised of chemically tempered glass separated by interlayers of polyvinyl butyral and urethane the glass and interlayer materials are bonded together in an autoclave under specific time temperature and pressure conditions.the window is designed to withstand fail safe pressure loads with a single glass ply failed and normal pressure loads with multiple glass plies failed the windshield heat system is normally powered whenever the aircraft electrical system is powered.the anti ice and anti fog elements are connected to separate power and sensor terminal blocks located on the upper and lower edges of the windshield exemple 205 electric heating.electric heating.

In flight a cantilever wing of an aeroplane containing fuel is subjected to ?

Question 17-24 : Highest at the wing root equal to the zero fuel weight multiplied by the span equal to half the weight of the aircraft multiplied by the semi span lowest at the wing root

A good example for a cantilever wing airplane is the cessna 177 . 807.on the ground and in flight the highest bending moment is at the wing root since there is no external supports as for a cessna 172 for example . 808 exemple 209 highest at the wing root.highest at the wing root.

The purpose of static wick dischargers is to ?

Question 17-25 : Dissipate static charge of the aircraft in flight thus avoiding radio interference as a result of static electricity dissipate static charge from the aircraft skin after landing provide a path to ground for static charges when refuelling be able to fly higher because of less electrical friction

The goal is to maintain the electrical airframe potential at around 10000 volts via the static dischargers by providing a path for the electrons.example of static dischargers on a wing . 810..without static dischargers the electrical airframe potential would rise up to a value 10 times higher and would disturb and/or damage the onboard equipment exemple 213 dissipate static charge of the aircraft in flight thus avoiding radio interference as a result of static electricity.dissipate static charge of the aircraft in flight thus avoiding radio interference as a result of static electricity.

Electrical bonding of an aircraft is used to .1 protect the aircraft against ?

Question 17-26 : 1 3 and 4 1 2 and 3 3 and 4 2 and 4

Good electrical bonding will reduce the damage to the airframe structure in the event of a lightning strike.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 exemple 217 1, 3 and 41, 3 and 4

One indication of inadequate bonding of aircraft components may be ?

Question 17-27 : Static noises can be heard on the radio there is interference on the vor receiver a circuit breaker pops out there is heavy corrosion on the fuselage skin mountings

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 exemple 221 static noises can be heard on the radio.static noises can be heard on the radio.

The reason for the fact that an aeroplane designed for long distances cannot ?

Question 17-28 : The lifetime of the fatigue sensitive parts has been based on a determined load spectrum the procedures and checklists for this kind of aeroplanes will take too much time these aeroplanes often consume too much fuel on short haul flights in that case some fuel tanks remain empty during the whole flight which stresses the aeroplane's structure in an unacceptable way

Take for example the pressurization depressurizations cycles .the more cycles you do short flights the more fatigue the structure gets if you use an airbus a340 for short hauls as the aircraft has not been designed for that it is more susceptible to 'low cycle fatigue damages' compared to an airbus a320 .note once at cruise level the fatigue remains the same it is not time related it is cycle related.all nippon airways and japan airlines are the best known users for the special boeing 747 400d domestic a high density seating model developed for short haul domestic japanese flights the aircraft is capable of seating a maximum of 568 passengers in a 2 class configuration or 660 passengers in a single class configuration the 400d lacks the wing tip extensions and winglets included on other variants allowing for increased number of takeoffs and landings by lowering wing stresses the benefits of winglets would be minimal on short routes..the 747 400d is also unusual in having more windows on both sides of the upper deck than the basic 400 series this allows for additional seating all the way down the upper deck where a galley is situated on most international models exemple 225 the lifetime of the fatigue sensitive parts has been based on a determined load spectrum.the lifetime of the fatigue sensitive parts has been based on a determined load spectrum.

Engine compartment decking and firewalls are manufactured from ?

Question 17-29 : Stainless steel or titanium sheet composite materials such as carbon kevlar and fibre glass aluminium alloy sheet asbestos blankets

exemple 229 stainless steel or titanium sheet.stainless steel or titanium sheet.

The inner surface of a heated windscreen is of ?

Question 17-30 : Soft polycarbonate triplex glass hard perspex

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 exemple 233 soft polycarbonate.soft polycarbonate.

The purpose of stringers used in fuselage construction is to ?

Question 17-31 : Assist the skin withstand longitudinal compressive loads withstand shear stresses provide sound and thermal isolation carry the loads due to pressurisation and convert them into tensile stress

exemple 237 assist the skin withstand longitudinal compressive loads.assist the skin withstand longitudinal compressive loads.

Significant torsion effects in a wing during flight can be caused by ?

Question 17-32 : Aileron deflection wing tip vortices propwash wing dihedral

The two deformation modes that cause wing flutter are ?

Question 17-33 : Torsion and bending torsion and shearing bending and elongation shearing and elongation

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 exemple 245 torsion and bending.torsion and bending.

One design method to avoid control surface flutter is ?

Question 17-34 : Ensuring correct mass distribution within the control surface through the correct use of balance tabs through the correct use of trim tabs providing the wing structure with sufficient flexibility

A composite structural component consists of ?

Question 17-35 : A matrix and fibres two thin metal sheets and a light core material aluminium alloy with a covering layer of pure aluminium two metal sheets bonded together

exemple 253 a matrix and fibres.a matrix and fibres.

The fuselage structure of a pressurised transport aeroplane is an example of a ?

Question 17-36 : Semi monocoque structure truss type structure pure monocoque structure sandwich 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 exemple 257 semi-monocoque structure.semi-monocoque structure.

When a wing bends downwards aileron flutter might occur if the aileron deflects ?

Question 17-37 : Upwards because the location of the aileron centre of gravity lies behind the hinge line upwards because the location of the aileron centre of gravity lies in front of the hinge line downwards because the location of the aileron centre of gravity lies behind the hinge line downwards because the location of the aileron centre of gravity lies in front of 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 exemple 261 upwards, because the location of the aileron centre of gravity lies behind the hinge line.upwards, because the location of the aileron centre of gravity lies behind the hinge line.

A structure in which the skin takes all of the load is ?

Question 17-38 : A monocoque structure a semi monocoque structure a semi braced structure a box 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 exemple 265 a monocoque structure.a monocoque structure.

A cantilever wing is ?

Question 17-39 : A wing attached to the fuselage at the wing root only a wing planform other than rectangular a high wing configuration a low wing configuration

A good example for a cantilever wing airplane is the cessna 177. 807 exemple 269 a wing attached to the fuselage at the wing root only.a wing attached to the fuselage at the wing root only.

A non cantilever wing is ?

Question 17-40 : A wing supported by braces or a strut connected to the fuselage a wing planform other than rectangular a high wing configuration a low wing configuration

exemple 273 a wing supported by braces or a strut connected to the fuselage.a wing supported by braces or a strut connected to the fuselage.

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