Question 31-1 : Loads on the cylindrical part of the fuselage during pressurisation are carried by the ? [ License IFR ]

Question 31-2 : The bending loads on a cantilever wing due to lift are carried by the 1 upper skin surface2 lower skin surface3 wing root fairing4 spar or sparsthe combination that regroups all of the correct statements is ?

1 2 4.

A good example for a cantilever wing airplane is the cessna 177 807whilst stationary on the ground in a hangar the most important loads on a cantilever wing are tension in the upper surface compression in the lower surface 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 topthe wing structure elements which take up the vertical bending moments mx are the spars

Question 31-3 : Which of these statements about structural design principles are correct or incorrect i in structural design fail safe implies redundant load pathsii a safe life structure is based on a declared number of cycles or time period ?

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 componentsif 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 inspectionthe philosophy of fail safe is to anticipate a possible failure with a minimum of harmin a safe life construction the components are given for a time period andor number of cycles x landings x engine starts and must be removed from service when the appropriate criteria are metthe 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

Question 31-4 : 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 materialii a sandwich structural part is not suitable for absorbing concentrated loads ?

I is correct ii is correct.

A sandwich structural part is composed of two thin sheets and a light core material 814the mechanical properties of a sandwich structural part are not suitable for bending the honeycomb structure will break or undergo a permanent deformation 814

Question 31-5 : 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 sheetsii a sandwich structural part is unsuitable for absorbing concentrated loads ?

I is correct ii is correct.

A sandwich structural part is composed of two thin sheets and a light core material 814the mechanical properties of a sandwich structural part are not suitable for bending the honeycomb structure will break or undergo a permanent deformation 937

Question 31-6 : According jarcs 25 the worst effect of a hazardous failure on the occupants of an aeroplane excluding flight crew could be ?

Serious or fatal injury to a small number of passengers or cabin crew.

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Question 31-7 : For safe life designed structural components 1 there is more than one load carrying component2 one load carrying component is sufficient for a given load provided it is strong enough3 the component is removed at the end of the calculated life time or number of cycles4 the design is based on the ?

2 3.

The safe life principle is based on the replacement of parts after a given number of cycles or time period in structural design safe life implies the structure will shouldn't fail during a declared time period or number of cyclesthe safe life design technique is employed in critical systems which are either very difficult to repair or may cause severe damage to life and propertysafe life structures are employed when the cost or infeasibility of inspections outweighs the weight penalty and development costs associated with safe life structuresan example of a safe life component is the helicopter rotor blade due to the extremely large numbers of cycles endured by the rotating component an undetectable crack may grow to a critical length in a single flight and before the aircraft lands result in a catastrophic failure that regular maintenance could not have prevented

Question 31-8 : According jarcs 25 the allowable average failure probability per flight hour probability for a major failure should be on the order of ^ means to the power of ?

Between 10^ 5 and 10^ 7 remote.

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Question 31-9 : According jarcs 25 the allowable average failure probability per flight hour for a 'minor' failure should be on the order of means to the power of ?

Between 10^ 3 and 10^ 5 probable.

Certification specifications for large aeroplanes cs 25 book 2 acceptable means of compliance pdf652

Question 31-10 : According jarcs 25 the allowable quantitative average failure probability per flight hour for a catastrophic failure should be on the order of ^ means to the power of ?

Less than 10^ 9 extremely improbable.

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Question 31-11 : According jarcs 25 the worst effect of a hazardous failure on the flight crew could be ?

Physical distress or excessive workload impairs ability to perform tasks.

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

Question 31-12 : According jarcs 25 the worst effect of a hazardous failure on the aeroplane could be ?

Large 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

Question 31-13 : Which of these statements about structural design principles are correct or incorrect 1 in structural design fail safe implies the structure will never fail2 in structural design safe life implies the structure will never fail during a declared time period or number of cycles ?

I is incorrect ii is incorrect.

In a fail safe construction the components were designed in a way that the loads are shared among adjacent componentsif 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 inspectionthe philosophy of fail safe is to anticipate a possible failure with a minimum of harmin a safe life construction the components are given for a time period andor number of cycles x landings x engine starts and must be removed from service when the appropriate criteria are metthe safe life design technique is employed in critical systems which are either very difficult to repair or may cause severe damage to life and propertystatement 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

Question 31-14 : Which of these statements about structural design principles are correct or incorrect 1 the damage tolerance principle takes cracking of the structure into account2 the safe life principle is based on the replacement of parts after a given number of cycles or flight hours ?

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 accountin a safe life construction the components are given for a time period andor number of cycles x landings x engine starts and must be removed from service when the appropriate criteria are met

Question 31-15 : Which of these statements about structural design principles are correct or incorrect 1 the damage tolerance principle assumes cracks in the structure will never occur2 the safe life principle is based on the replacement of parts after a given number of cycles or time period ?

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 accountin a safe life construction the components are given for a time period andor number of cycles x landings x engine starts and must be removed from service when the appropriate criteria are met

Question 31-16 : Which of these statements about structural design principles are correct or incorrect 1 in structural design fail safe implies the structure will never fail2 a safe life structure is based on a declared time period or number of cycles ?

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 componentsif 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 inspectionthe philosophy of fail safe is to anticipate a possible failure with a minimum of harmin a safe life construction the components are given for a time period andor number of cycles x landings x engine starts and must be removed from service when the appropriate criteria are metthe safe life design technique is employed in critical systems which are either very difficult to repair or may cause severe damage to life and propertystatement i is incorrect because you can not guarantee that a part will definitely not will never fail

Question 31-17 : According jarcs 25 the worst effect of a minor failure on the occupants of an aeroplane excluding flight crew could be ?

Physical discomfort.

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

Question 31-18 : According jarcs 25 the worst effect of a major failure on the occupants of an aeroplane excluding flight crew could be ?

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

Question 31-19 : According jarcs 25 the worst effect of a catastrophic failure on the aeroplane could be ?

Hull loss.

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Question 31-20 : According jarcs 25 the allowable quantitative average failure probability per flight hour for a hazardous failure should be on the order of ^ means to the power of ?

Between 10^ 7 and 10^ 9 extremely remote.

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

Question 31-21 : According jarcs 25 the worst effect of a minor failure on the flight crew could be ?

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

Question 31-22 : According jarcs 25 the worst effect of a major failure on the flight crew could be ?

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

Question 31-23 : According jarcs 25 the worst effect of a minor failure on the aeroplane could be ?

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

Question 31-24 : According jarcs 25 the worst effect of a catastrophic failure on the flight crew could be ?

Fatalities or incapacitation.

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

Question 31-25 : The principle of damage tolerance in structural design of an aircraft is based on the ?

Capability to withstand a certain amount of weakening of the structure without catastrophic failure.

Damage tolerant components will not have a specified life continued operation is based on frequent inspections and takes cracking of the structure into account

Question 31-26 : The principle of on condition maintenance is based on the ?

Monitoring of critical parameters and the replacement of parts if a limit value is exceeded.

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

Question 31-27 : The principle of fail safe design of an aircraft is based on the ?

Redundancy of the structure or equipment.

In a fail safe construction the components were designed in a way that the loads are shared among adjacent componentsif 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 inspectionthe philosophy of fail safe is to anticipate a possible failure with a minimum of harm

Question 31-28 : A safe life aircraft structural component ?

May be used during a declared number of cycles or flight hours.

In a safe life construction the components are given for a time period andor number of cycles x landings x engine starts and must be removed from service when the appropriate criteria are metthe 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

Question 31-29 : Whilst stationary on the ground in a hangar the most important loads on a cantilever wing are ?

Question 31-30 : In straight and level flight the most important loads on a cantilever wing are ?

Compression in the upper surface tension in the lower surface.

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

Question 31-31 : Define the term 'fatigue' ?

If a material is continually loaded and unloaded it will eventually break even though the load remains the same.

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

Question 31-32 : Which of these statements about structural design principles are correct or incorrect i in structural design fail safe implies parallel structural partsii in structural design safe life implies the structure will never fail during a declared time period or number of cycles ?

I is correct ii is incorrect.

In a fail safe construction the components were designed in a way that the loads are shared among adjacent componentsif 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 inspectionthe philosophy of fail safe is to anticipate a possible failure with a minimum of harmin a safe life construction the components are given for a time period andor number of cycles x landings x engine starts and must be removed from service when the appropriate criteria are metthe safe life design technique is employed in critical systems which are either very difficult to repair or may cause severe damage to life and propertystatement 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

Question 31-33 : At point 1 the load moment is 2760 ?

Tension.

Question 31-34 : On modern transport aircraft cockpit windows are protected against icing by ?

Electric heating.

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 conditionsthe 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

Question 31-35 : In flight a cantilever wing of an aeroplane containing fuel is subjected to vertical loads that produce a bending moment which is ?

Highest at the wing root.

A good example for a cantilever wing airplane is the cessna 177 807on 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

Question 31-36 : The purpose of static wick dischargers is to ?

Dissipate static charge of the aircraft in flight thus avoiding radio interference as a result of static electricity.

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 810without static dischargers the electrical airframe potential would rise up to a value 10 times higher and would disturb andor damage the onboard equipment

Question 31-37 : Electrical bonding of an aircraft is used to 1 protect the aircraft against lightning effects2 reset the electrostatic potential of the aircraft to a value approximating 0 volt3 reduce radio interference on radio communication systems4 set the aircraft to a single potentialthe combination regrouping ?

1 3 and 4.

Good electrical bonding will reduce the damage to the airframe structure in the event of a lightning strikebonding is the electrical interconnection of metallic aircraft parts normally at earth potential for the safe distribution of electrical charges and currentsbonding 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 endangeredbonding reduces the possibility of electric shock from the electrical supply system reduces interference with the functioning of essential services eg radio communications and navigational aids and provides a low resistance electrical return path for electric current in earth return systems

Question 31-38 : One indication of inadequate bonding of aircraft components may be ?

Static noises can be heard on the radio.

Bonding is the electrical interconnection of metallic aircraft parts normally at earth potential for the safe distribution of electrical charges and currentsbonding 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 endangeredbonding reduces the possibility of electric shock from the electrical supply system reduces interference with the functioning of essential services eg radio communications and navigational aids and provides a low resistance electrical return path for electric current in earth return systems

Question 31-39 : The reason for the fact that an aeroplane designed for long distances cannot simply be used for short haul flights at higher frequencies is that ?

The lifetime of the fatigue sensitive parts has been based on a determined load spectrum.

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 a320note once at cruise level the fatigue remains the same it is not time related it is cycle relatedall 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 routesthe 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

Question 31-40 : Engine compartment decking and firewalls are manufactured from ?

Stainless steel or titanium sheet.