Airplane system(现代飞机系统与结构复习题)

Airplane system

1.What is the purpose of the wing main spar?

To withstand bending and torsional loads.

2.What is the purpose of wing ribs?

To shape the wing and support the skin.

3. what is the purpose of stringers?

To prevent buckling and bending by supporting and stiffening the skin.

4.the airframe structure must remain substantially intact after

experiencing:

the design limit load times a 1.5 factor of safety

5. in the construction-of airframes the primary purpose of frames or formers is to:

Oppose hoop stresses and provide shape and form to the fuselage.

6.how can wing bending moments be reduced in flight?

By using aileron up-float and using the fuel in the wings last

7.regarding a safe life structure:

should not fail until a predicted number of fatigue cycles has been achieved.

Has a programmed inspection cycle to detect and rectify faults.

Is changed before its predicted life is reached.

8.A fail safe structure:

Has a programmed inspection cycle to detect and rectify faults.

Has redundant strength which will tolerate a certain amount of structural damage.

9.The skin of a modern pressurized aircraft: is primary load bearing

structure carrying much of the structural loads.

10.T he primary purpose of the fuselage is to house the crew and payload.

11.S tation numbers and water lines are a means of locating airframe

structure and components.

12.F light deck windows are constructed from strengthened glass with

shock absorbing clear vinyl interlayers and rubber pressure seals.

13.A cantilever wing is supported at one end only with no external bracing.

14.A torsion box is a structure formed between the sing spars, skin and

ribs to resist bending and twisting loads.

15.A lightening hole in a rib collects and disposed of electrical charges.

16.C ontrol surface flutter is a means of predicting the critical safe life of

the wing.

17.C ontrol surface flutter is minimized by mass balance of the control

surface.

18.A damage tolerant structure has degree of structural strength

redundancy spread over a large area.

19.A ircraft structures consists mainly of aluminium alloy sheets and rivets

with titanium or steel materials at points requiring high strength. 20.T he maximum zero fuel mass(MZFM) of an aircraft is the maximum

permissible mass of an aircraft with zero payload.

Chapter two

1.A force of 100N is applied to 2 separate jacks, the area of one is

0.02m2d the other is 0.04m2: the smaller jack will exert a pressure

of 5000pa and the larger 2500pa.

2.A pre charge pressure of 1000bar of gas is shown on the

accumulator gauge. The system is then pressurized to 1500bar, so the accumulator will read 1500bar.

3.The pressure gauge of an hydraulic system provides information

regarding the pressure of the hydraulic fluid in the system.

4.A shuttle valve allows two supply sources to operate one uint.

5.Def.stan 91/48 is red and is mineral baded.

6.A restrictor valve controls the rate of movement of a service.

7.With a hyd lock there is no flow, jack is stationary.

8.The hydraulic fluid is changed, but the wrong fluid is replaced. This

would lead to system failure from leaks and blocked filters, high temp and possible corrosion.

9.Accumulator floating piston provides a seal between the gas and

fluid.

10.A relief valve relives at its designed pressure.

11.T he primary purpose of a hydraulic reservoir is to compensate for

leaks, displacement and expansion.

12.W ith air in the hydraulic system you should bleed the air out of the

system.

13.T he pressure filter in a hydraulic system is fitted down stream of the

pump.

14.P ascal’s law states that applied force acts equally in all directions.

15.A constant pressure hydraulic pump is governed by a control

piston.

16.A high pressure hydraulic pump needs a positive fluid supply.

17.C ase drain filters are to enable pump lubricating fluid to be used to

monitor pump condition.

18.T he purpose of an accumulator is to store fluid under pressure.

19.W ith a one way check valve(NRV) flow stops when input pressure is

less than output pressure.

20.A restrictor valve is physically fitted in the u/c up line and flap up

line.

21.I n the case of a failure of a cut-out valve a full flow relief valve is

fitted down stream of it.

22.H ydraulic pressure of 3000pa is applied to an actuator, the piston

area of which is 0.02m2and the same pressure is exerted on actuator whose area is 0.04m2. the smaller jack will exert a force of 60N and the larger 120N.

23.A separator in an accumulator isolate the gas from the fluid.

24.I n an operating hydraulic actuator the pressure of the fluid will be

the same at all points.

25.T he contents of the hydraulic fluid reservoir are checked. They

indicate that the reservoir is at fall below the “full” mark.

26.A pressure maintaining or priority valve is used to ensure available

pressure is directed to essential services.

27.A hydraulic lock occurs when flow is stopped and the actuator is not

able to move.

28.I n an enclosed system pressure is felt the same at both ends

between the piston and the cylinder head.

29.A non return valve close fi inlet pressure ceased.

30.L ow gas pressure in accumulator causes rapid pressure fluctuations

while system is operating.

31.H ammering in system is detrimental to the system.

32.T he specification of hydraulic fluids, mineral, vegetable or ester

based is cannot be distinguished by colour alone.

33.A n ACOV will provide an idling circuit when the accumulator is fully

charged.

34.T he purpose of a hydraulic fuse is to prevent total loss of system

fluid if the brake pipeline is ruptured.

35.A shuttle valve will allow two independent pressure sources to

operate a system component.

36.T he purpose of a reservoir is to compensates for small leaks,

expansion and jack displacement.

37.W hen the hydraulic system pressure is released reservoir fluid

contents will rise if reservoir is lower than other components in the system.

38.H ydraulic pressure in a closed system.

39.S kydrol hydraulic fluid is flame resistant but is harmful to skin, eyes

and some paints.

40.S kydrol hydraulic fluid can be used to replenish hydraulic systems

that have butyl rubber seals only.

41.A variable displacement pump on system startup will be at

maximum stroke.

42.T he purpose of a reservoir is to allow for fluid displacements,small

leaks, thermal expansion and contents.

43.H ydraulic thermal relief valves are fitted in isolated lines only to

relieve excess caused by temperature rises.

44.A main system hydraulic pump always needs a positive fluid supply

in order to prevent cavitation.

45.D ifferent diameter actuators supply with the same pressure at same

rate exert different forces.

46.A force of 1500 N is applied to a piston of area 0.002m2and

generates a force of 2250N,a piston of area 0.003 m2, the pressure generated is 750000pa and if the smaller piston moves 0.025m, the work done is 37.5j.

47.T he following statements relate to hydraulic accumulators. The

function of a accumulator is to :

Store fluid under pressure;

Dampen pressure fluctuations;

Allow for fluid expansion

Allow for thermal expansion.

Prolong the period between pump cut-in and cut out.

Provide an emergency reserve of pressure in the event of pump failure.

48.T he seal materials used with hydraulic fluids to DFF/STAN 91-48 and

SKYDROL 700 specification are respectively neoprene and butyl.

49.T o prevent cavitation of the pump a hydraulic reservoir may be all

of the above.

50.A hand pump is usually fitted for ground servicing purposes.

Chapter three.

1.Oil is in an oleo strut to limit the speed of extension and compression

of the strut.

2.The nose wheel assembly must be centered before retraction because

there is lilmited space in nose wheel bay.

3.The movement of the gear on lowering is normally damped to

counteract the force of gravity which would bring the gear down too fast.

4.Inadvertent retraction of the landing gear on the ground is always a

danger after the ground is always a danger after the ground locks have been removed.

5.Creep(slippage): can rip out the inflation valve on tubed tyres, and

deflate the tyre.

6.Tyre wear when taxying can be reduced taxying at less than 40kph.

7.To prevent srubbing the tyres while taxying, you should turn to sharper

than the minimum specified radius.

8.The best extinguishant to use on a wheel or brake fire is dry powder.

9.When inflating a tyre fitted to an aircraft, the tyre pressure reading on

the gauge should be modified by 4%.

10.T he most likely cause of brake fade is the brake pads overheating.

11.T he pressure needed to operate the wheel brakes on a large aircraft

comes from the aircraft main hydraulic system.

12.W hich of the following statements will produce the shortest landing

run:

Crossing the threshold at the correct height and speed;

Applying full anti-skid braking as quickly as possible after touchdown.

Application of reverse thrust as early in the landing run.

Deployment of the lift dumpeers/speed brakes as early as possible in the landing run.

13.T he formula which gives the minimum speed at which aquaplaning

may occur is vp=9x.

14.A n aircraft has a tyre pressure of 225psi, its minimum aquaplaning

speed will be 135knots.

15.L anding gear ground locking pins are removed prior to flight and

stowed on the aircraft where they are visible to the crew.

16.T he most likely cause of brake unit dragging is incorrect operation of

the adjuster assemblies.

17.A likely cause of nose wheel shimmy is a torque link is worn or

damaged.

18.C reep can be measured by painting marks on the tyre and wheel rim.

19.T he anti-skid system would be used for both take off and landing runs.

20.A hydraulic gear extension/retraction mechanism consists of sequence

valves, uplocks and down locks.

21.A nose wheel steering control system allows the nose wheel to caster

within preset limits about the neutral positon.

22.A t an aircraft taxying speed of 10mph the antiskid braking system is

inoperative.

23.T he tyre pressures are checked after a long taxi to the ramp following

landing. The pressure will have risen by 10% of their original weight-

on-wheels value.

24.T he ply rating of a tyre is the index of the tyre strength.

Chapter four

1.The purpose of pulley wheels in cable control system is to change

the direction of the control cable.

2.The purpose of the primary stops in a control system is to set the

range of movement of the control surface.

3.The purpose of the secondary stops in control system is to limit

control surface range in the event of primary stop fail.

4.The purpose of the fairleads in a cable control system is to keep

the cable straight and clear of structure.

5.In a cable control system cables are tensioned to

Remove backlash from the control linkage;

Provide positive action in both directions.

Compensate for temperature variations.

6.In a cable control system the cables are mounted in pairs to:

Provide positive action in both directionsl.

7.In a manual flying control system the control inputs to the primary

control surface are reversible and instinctive for the movement required.

8.To yaw the aircraft to the right the right rudder pedal is pushed

forward and the rudder moves to the right.

9.To roll the aircraft to the right: the aileron control is moved to the

right, the right aileron goes up and the left one down.

10.T he advantages of a cable control are :

Light,very good strength to weight ratio.

Easy to route through the aircraft

Less prone to impact damage

Takes up less volume

Chapter four

1.Main and nose wheel bays are unpressurised.

2.Normal maximum negative differential pressure is when atmospheric

pressure

3.When would the negative differential limit be reached/exceeded rapid

descent when AC descends below cabin altitude.

4.A/C in level flight if cabin altitude cabin altitude increases does

pressure diff decreae.

5.In level pressurized flight does the outflow valve adjust to provide

constant flow, and is normally partially open.

6.In a turbo cooler system is the cooling air: ram air.

7.The rate of change of cabin pressure should be kept to the minimum.

Is this more in descent.

8.Is a cabin humidifier at highaltitude.

9.Fatigue life of the fuselage is based on the number of explosive

decompressions.

10.I f the forward oil seal in an axial flow compressor fails, will air be

contaminated.

11.R ate of change of cabin altitude is shown on a special gauge.

12.C abin discharge valve is supplied with cabin and static pressure.

13.O n what principle does the vapor cycle cooling system work on liquid

into vapor.

14.W hat is the purpose of the duct relief valve to prevent damage to the

ducts.

15.W hat system is installed to control the air conditioning impingement

type dehydrator and humidifier.

16.H ow is the air cooled in a booststrap(turbo-compressor) system?

By expanding over turbine driving compressor.

17.A t the max differential phase, is the discharge valve open.

18.W hat is the purpose of inward relief valves：to prevent negative

differential.

19.O n a ground pressuisation test, if the cabin suffers a rapid de-

pressurisation: water precipitation will occur.

20.A heat exchanger functions by: passing charge air through ducts and

cool air around ducts.

21.M aximum differential pressure is the maximum authorized pressure

difference between the inside of the fuselage a the atmospheric ambient pressure.

22.A humidifier is fitted to increase the moisture content in the air when

operating at high altitude .

23.I f the discharge or outflow valve close the safety valve would limit the

positive pressure difference.

24.A ir for conditioning and pressurization is taken from the engine

compressor or cabin compressor.

25.S afety valves are biased inwards.

26.C abin compressors increase their flow in proportion to increases of

altitude differential pressure and reduction in engine RPM in order to maintain the mass flow.

27.I n a pressurization circuit the sequence of operation is for the outflow

valve to operate before the safety valve.

28.W ith the QFE set on the cabin controller, against an altitude of zero:

the cabin will be unpressurised on landing.

29.I n the cruise at 300000ft the cabin altitude is adjusted from 4000ft to

6000ft: cabin differential will decrease.

30.A n aircraft climbs from sea level to 16000ft at 1000ft per min, the cabin

pressurization is set to climb at 500ft per min to a cabin altitude of 8000ft. the time taken for the cabin to reach 8000ft is the same time as it takes the aircraft to reach 16000ft.

31.T he aircraft inhibiting switch connected to the A/C landing gear: stops

pressurizing on the ground and ensures that there is no pressure differential.

32.N egative differential is limited by inward relief valve.

33.S equence of air through a vapour cooling system is turbine then

expansion valve.

34.T o maintain a steady and constant airflow regardless of altitude or

cabin pressure: a mass flow controller is fitted.

35.T he term pressurization cycle means air introduced into a fuselage

under pressure until the time the air is released.

36.I nward relief valves operate automatically when there is a negative diff.

37.S afety valves operate at higher diff than discharge valve.

38.D itching cocks are operated to shut all outflow valves.

39.D uct relief valves operate when excessive pressure builds up in the air

conditioning systems.

40.D uring a normal pressurized cruise, the discharge valve position is

partially open.

41.A dump valve is controlled manually.

42.W hen air is pressurized the % of oxygen: remains the same.

43.I f pressure is manually controlled: care should be taken to ensure

climb/descent rates are safe.

44.A n aircraft is prevented from pressurizing on the ground by inhibiting

micro switches on the landing gear.

45.I f the pressureisaotn air is passed over the cold air unit compressor

does it: increase the charge air temperature.

46.I f the cabin pressure increased in level flight does the cabin VSI show:

rate of descent.

47.C abin sltitude in pressured flight is the altitude corresponding to cabin

pressure regardless of aircraft height.

48.T he term pressure cabin is used to describe the ability to pressurize the

aircraft to a higher than ambient presser.

49.A pressurization system works by essentially constant input mass flow

and variable output.

50.W hen air is pressurized by an engine driven compressor ,it is also

heated.