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Tech Questions > 178 > Flashcards

178 Flashcards

1
Q

Cathay Pacific

Explain the NTS system in the Metro.

A

The NTS system intermittently increases the blade angle to reduce drage to minimum.Negative torque occurs when the propeller begins to drive the negine, such as if an engine loses power. NT must be limited because of the accompanying drag. It cannot be limited to zero however, otherwise a windmilling airstart will not be possible.Neg torque will close the NTS valve. Pressure wil build up and position the feathering valve to the feather position, and dome oil will drain to the sump, allowing the springs and counterweight to increase blade angle until a positive torque is produced by the preloaded torque arms. The NTS valve will open again, and the feathering valve will return to normal.

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2
Q

Cathay Pacific

Where is fuel stored in the 747-400?

A

1x reserve, & 2x main tanks per wing1x center wing tank1x stabiliser tank

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3
Q

Cathay Pacific

What are the forces in a climb?

A

Lift > WeightThust > DragThe vertical component of excess thrust balances weight

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4
Q

Cathay Pacific

What are the forces in a descent?

A

Lift < WeightLift & Drag balance Weight

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5
Q

Cathay Pacific

What are the forces in straight & level flight?

A

Lift = WeightThrust = Drag

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6
Q

Cathay Pacific

What is required to calculate Mach Number?

A

pressure altitudeindicated airspeed

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7
Q

Cathay Pacific

What are the disadvantages of a swept wing?

A

Oscillatory stability poorLift at low speeds poorStall speed increasedAoa higher at the stallTips stall firstMin drag speed high

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8
Q

Cathay Pacific

Why do we have a variable incidence tailplane?

A

CofG range is largeSpeed range is largeTrim changes large (particularly due to high lift LE and TE devices)Drage from trim reduced to minimum

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9
Q

Cathay Pacific

What is adverse yaw, and what reduces the effect of adverse yaw?

A

Adverse yaw is a secondary effect of the application of ailerons. The upgoing aileron (downgoing wing) produces a forward component of lift that yaws opposite to the turn.Frise aileronsDifferential aileronsFrise: Bottom protrudes enough to cause drag to balance the yawDifferential: The up-going deflects further than the down going aileron

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10
Q

Cathay Pacific

What is spiral stability?

A

The tendency of an aircraft in a co-ordinated turn, to return to laterally level flight on release of the ailerons.

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11
Q

Cathay Pacific

What is Lateral stability?

A

The tendency of aircraft in a side-slip, to return to laterally level flight on release of the ailerons.

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12
Q

Cathay Pacific

What is oscillatory stability?

A

‘Stable dutch roll’The tendency of an aircraft when disturbed, either directionally or laterlly, to damp out the yawing/rolling motion and return to steady flight.

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13
Q

Cathay Pacific

What is the relationship between temperature and the speed of sound?

A

Increase temp = increase speed of sound

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14
Q

Cathay Pacific

Explain the following airspeed corrections:IAS → CAS ?IAS → EAS ?EAS → TAS ?TAS → GS ?

A

Corrected for:IAS → CAS = installation errorIAS → EAS = compressibility errorEAS → TAS = air densityTAS → GS = headwind or tailwind

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15
Q

Cathay Pacific

What is VR ?

A

VR allows the aircraft to reach V2 before 35’

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16
Q

Cathay Pacific

What is V2 ?

A

the speed to fly following an eng failure at or after V1provides the necessary climb gradient for obstable clearance with an eng failedmust be attained prior to 35’not less than: 1.1 VMCA1.2 VS

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17
Q

Cathay Pacific

What is the freezing point of Jet A1?

A

-47oC

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18
Q

Cathay Pacific

What is long range cruise?

A

LRC provides a speed increase of up to 10%, fora range decrease of only 1%Faster than max range cruiseProvides excellent time savings for min fuel cost increaseRequires a gradual reduction in cruise speed as weight decreases with fuel burn off (to maintain a constant AoA)

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19
Q

Cathay Pacific

Explain stopway vs clearway

A

Stopway is the surface upon which the a/c can be stopped during a RTO. The surface may be damaged by the weight of the a/c.Clearway is the obstacle free surface over which the aircraft can fly whilst achieving screen height.

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20
Q

Cathay Pacific

Explain balanced field length

A

Where ASDR=TODR for an engine failure at V1

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21
Q

Cathay Pacific

What is ETOPS?

A

Extended range twin engine operational performance standardsAn ICAO rule permitting twin engined commercial air transport a/c to fly routes >60mins from the nearest diversion airport (1 Inop)ETOPS ratings are:75, 90, 120/138, 180/207Must have:Type approvalOperational certificationLROPS may replace ETOPS. Will apply to ALL airliners, not just twins.

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22
Q

Cathay Pacific

How can we adjust LSALT / MEA for ISA temp deviations?

A

For each deviation of 5oCchange by 2%Eg: ISA -25oC = Add 10% (5x2)

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23
Q

Cathay Pacific

How can we increase the take off weight, if 2nd segment TOW limited?

A

Increase V2

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24
Q

Cathay Pacific

What are the considerations for Polar route flights?

A

Considerations:enroute alternate airports (ETOPS)cold fuel managementcomms & navigationMagnetic headings in the polar region are unreliable, north of 74o latitude.Satcom not available above 82oN. (use Arctic radio on HF)Flight plan must show true tracks and headings.

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25
Q

Cathay Pacific

What are the advantages / disadvantagesof pod mounted engines?

A

Advantages:Interference drag is minimisedIntake efficiency is not compromised (pods are in clear air)Engines provide bending relief which reduces wing structure weightAt high angles of incidence the pylons tend to act as fences, reducing span-wise flowEase of accessiblity for engine maintenanceLess overall damage in the event of a gear-up landingLess acoustic damage to the airframeDisadvantages:Greater assymetric yawing momentRoll freedom close to the ground is reducedLow thrust line affect longitudinal controlLow mounted engines more susceptible to FOD

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26
Q

Cathay Pacific

What does a Constant Speed Drive do?

A

It drives a DC generator from variable RPM, providing constant DC generator frequency output.

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27
Q

Cathay Pacific

What is the error of an altimeter at 10,000’PH at ISA -34o?

A

Rule is every 5oC ISA deviation = 2%Therefore we are over-reading by 14% (7x2)

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28
Q

Cathay Pacific

Can a typhoon cross the equator?

A

Yes. Once established, it can cross about 5o of latitude into the opposite hemisphere. In so doing it will encounter opposing Coriolis force and rapidly decrease in strength.

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29
Q

Cathay Pacific

Tell me about a warm front?

A

Represents the leading edge of a warm air mass.Gentle slope (0.5-1o), so cirus, altostratus indicate its approach 12hrs or more before arrivalSlow movingAt the passage of a warm front:Wind veersTemp risesFall of pressure is checked

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30
Q

Cathay Pacific

Tell me about a cold front?

A

Represents the leading edge of a cold air massSteeper slope (2o)Unstable conditions ahead of the frontFast moving & shorter durationThunderstorm & precipitationAt the passage of a cold front:Wind veersTemp dropsPressure rises

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31
Q

Cathay Pacific

What is Clear Air Turbulence (CAT)?

A

Turbulence not associated with visible moistureMost likely to expect CAT just above the central core of the jet stream near the polar tropopauseDoes not occur in the coreEncountered more frequently in the Winter when jet stream winds are strongest

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32
Q

Cathay Pacific

What is a jet stream?

A

Narrow bands of high speed winds, generally between 20,000-40,000’ or moreClosely associated with the tropopause and the polar frontWinds flow from West to EastIf encountered, reduce speed to turbulence penetration speed

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33
Q

Cathay Pacific

What are the visual cues for a microburst?

A

VirgaLocalised blowing dustRain shafts with rain diverging away from the cellRoll cloudsLightning

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34
Q

Cathay Pacific

What are the effects of icing?

A

Lift decreasesWeight increasesThrust decreasesDrage increasesFuel consumption increasesStall speed increasesOptions:Descend to warmer airDivert to warmer airAvoid cloud / visible moisture

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35
Q

Cathay Pacific

Describe fuel management in the 747-400?

A

Center tankStab tankInboard tanks (down to prescribed lvl)Tank to engine

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36
Q

Cathay Pacific

Why do we usually set takeoff EPR prior to 80kts?

A

EPR will DECREASE at some point after 80kts due to ram effect, and this is why is must be set prior (to avoidincorrectly increasing thrust and over temping the engines)

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37
Q

Cathay Pacific

At what temps do Rime ice & Clear ice form?

A

Rime -10 to -20oCClear 0 to -15oC

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38
Q

Cathay Pacific

What is TSFC

A

Thrust specific fuel consumptiondefined as fuel-flow per pound of thrust produced

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39
Q

Cathay Pacific

How do you recover from dutch roll?

A

Don’t rush the recovery - watch the motion and get the patternOne firm but gentle applicatin of aileron against the up-going wingThe majority of the motion should now be gone. Use small aileron inputs to dampen out the rest.

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40
Q

Cathay Pacific

What is mach tuck?

A

As an aircraft approaches Mcrit it experiences an increasing nose down trim change due to:CP moves aft as shockwave forms on upper surfaceReduced download on the tailplane due to changing downwash from the wing

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41
Q

Cathay Pacific

What is a mach trimmer?

A

Artificially compensates for longitudinal instability at high mach numbersProvides an increasing push force all the way to Mdf

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42
Q

Cathay Pacific

What is the service ceiling of the Metro 23?

A

25,000’

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43
Q

Cathay Pacific

Explain the windshear alerting system in the B777?

A

It is part of the wx radar and uses radar imaging to detect air movements (precipitation rates) prior to entering the windshear area.The system is activated on the ground, when the wx radar is activated or automatically on ground when thrust levers are set for takeoff or automatically in the air below 2300 ft.There are two aural warning alerts for takeoff and approach and a caution alert to monitor radar display. The cautionary alert and warnings have visual cues provided on the ND as well.

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44
Q

Cathay Pacific

Tell me what vortex generators are and how they work?

A

VG’s are small vanes placed on the upper surface to re-energise the boundary layer and delay flow separation. (increasing MTOW and reducing stall speed)A vortex generator creates a tip vortex which draws energetic, rapidly-moving air from outside the slow-moving boundary layer into contact with the aircraft skin.

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45
Q

Cathay Pacific

What are the differences between the 777-300 and the 777-300ER?

A

777-200:336 Pax777-300:385 PaxLarger engines10mtr fuselage stretch777-300ER:301 PaxLarger enginesHigher MTOWIncreased fuel capacityRaked wintips

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46
Q

Cathay Pacific

How is the 777 fuel system different to the A330/340 and the 747-400?

A

No trim / stab tank.All fuel is in the wing.

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47
Q

Cathay Pacific

Explain how jet streams are formed?

A

Jetstreamsare formed by warm equatorial air flowing to the polar regions. The rotation of the earth causes it to flow West to East in both the Northern and Southern Hemispheres.This abrupt change in temperature causes a large pressure difference, which forces the air to move.The flow of the jetstreams is also affected by the position of high and low pressure systems.Jetstreams include:The Polar Front jetstreamThe Equatorial jetstream (100 North & South)The Subtropical jetstream (300 North & South)

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48
Q

Cathay Pacific

What is Cathay’s longest route?

A

HKG - JFKApprox 16hrs, polar routeCrosses the date line (lose one day)Dep 0945…. Arr 1210

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49
Q

Cathay Pacific

Explain the difference between differential and non-differential spoilers?

A

Non-differential spoilers don’t supplement roll control when the speed brake is fully extended.Differential spoilers retract and supplement roll control when the speed brake is fully extended.

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50
Q

Cathay Pacific

How do you think you can help someone who loses situational awareness in the cockpit?

A

Maintenance of situational awareness occurs througheffective communications and a combination of the following actions:Recognise and make others aware when the team deviates from SOP’sMonitor the performance of other team members.Provide information in advance.Identify potential or existing problems (i.e. equipment-related or operational).Demonstrate awareness of task performance.Communicate a course of action to follow as needed.Clarifying expectations of all team members eliminates doubt

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51
Q

Cathay Pacific

Climbing at a constant Mach No, what happens to IAS and TAS. Why?

A

Climbing at a constant Mach No, both IAS and TAS will reduce.Since 0.82M = (0.82 x speed of sound)Speed of sound is related only to tempTherefore in a constant mach climb, 0.82times a reducing amount MUST result in a lower TAS.Since TAS is CAS corrected for altitude and temperature, then as TAS reduces, IAS will also reduce.

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52
Q

Cathay Pacific

Climbing at a constant Mach No, what happens to angle of attack?

A

It decreases.

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53
Q

Cathay Pacific

If you had to choose one of the following scenarios in that you must either abort from 10kts above V1, or continue a single engine takeoff from 10kts below V1, which would you choose and why?

A

Continue 10kts before V1. Same as a reduced V1 for wet take-off. Would result in a lower screen height of 15’.RTO anytime after V1 is inherently dangerous and has been the cause of many accidents.

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54
Q

Cathay Pacific

At what rate does temperature decrease with altitude?What’s the layer of the atmosphere called where the temperature stops decreasing?What altitude does this occur at?

A

The ELR is 20 per 1000’ up to 36,000’ where the temp remains constant at -560.This layer of the atmosphere is called the tropopause.

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55
Q

Cathay Pacific

What are the chances of a brake fire after a max weight abort after V1?

A

High, especially if a long taxy prior to takeoff has left the brakes at higher temperature.

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56
Q

Cathay Pacific

What is the tropopause and why do we need to know where it is?

A

The Tropopause and Outside Air Temp (Static Air Temp) are used for many things, some of which are predicting turbulence, performance (fuel flow rates, airspeed) and planning for fuel temperature.The tropopause marks a boundary between the troposphere and the stratosphere. It’s significance is that it marks the point where a relatively linear decrease in temperature stops ocurring, and temperature (for our purposes) actually begins to increase with altitude from there.The tropopause represents a global atmospheric inversion, which occurs at it’s highest altitudes over the equator, and it’s lowest altitudes over the poles. It marks the distinct difference between layers of the atmsophere.

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57
Q

Cathay Pacific

What are high bypass engines?

A

With this type of engine, not all the air passes through the engine core and combustion chamber. A large fan (N1) is added at the front of the compressor, and driven by an extra turbine at the rear of the engine.The fan produces thrust by giving a relatively small acceleration to a large mass or air (much like a propeller). This fan air by-passes the combusiton chamber and turbine via a duct around the outside of the engine core.This ratio is usually around 5:1 or more.

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58
Q

Cathay Pacific

What type of reversers does the 744 have?

A

Cold stream reverser.

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59
Q

Cathay Pacific

Tell me about variation, how do you use it?

A

Variation is the difference between magnetic North & true North.Magnetic to True = ADD variationTrue to Magnetic = SUBTRACT variation

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60
Q

Cathay Pacific

What is the difference between a typhoon and a monsoon?

A

A monsoonis alarge scale wind system caused by differences in the temperature of land and sea over the seasons.A typhoon is a tropical cyclone (a non-frontal synoptic scale low pressure system over tropical waters with thunderstorms and cyclonic surface winds).

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61
Q

Cathay Pacific

What is RNP, and what is a rule of thumb for RNP?

A

RNP is measure of the navigation performance accuracy necessary for operations within a defined airspace. ( It is an area where the aircraft must be at least 95% of the time.)RNP allows air traffic controllers to plan approach paths that manoeuvre the aircraft around obstacles and restricted or built up areas.This can result in a shorter approach when compared to the conventional procedure.The RNP defines the width of the airspace corridor required for the procedure.RNP capability is usually certified by the manufacture of the aircraft at the time of production however older aircraft can also be upgraded. It is quickly becoming a standard feature of modern aircraft.RNP uses the aircraft’s Flight Management System to integrate numerous sources of position data.

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62
Q

Cathay Pacific

What is the transition altitude in HK?

A

Transition altitude is 9000’TL = FL110 (QNH 980 or above at airport)TL = FL120 (QNH 979 or below at airport)

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63
Q

Cathay Pacific

What are the different types of deicing fluid?

A

Type I (sprayed on hot, used for de-icing. Short holdover time)Type II (only used for larger aircraft. thickener agent)Type III (used for slower aircraft)Type IV (used for anti-icing after deicing with type I. longer holdover time. Green colour)

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64
Q

Cathay Pacific

If there’s frost under the wing, can you take off?

A

Yes, if authorised by the authority, in company FOM, and within specified limits.

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65
Q

Cathay Pacific

When does the holdover time begin?

A

The holdover time for deicing begins at the the time of the first point of application of deicing fluid.

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66
Q

Cathay Pacific

What is the start procedure in your aircraft?

A

Actuate the start switchLight off within 10secs after 10% RPMRelease start switchMonitor acceleration and EGT (manual fuel enrichment may be used)60% RPM engine is self sustainingcontinued acceleration to stabilised at 71% RPM

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67
Q

Cathay Pacific

How much fuel would we have on landing in HK after a long trip in a 744?

A

Fixed reservemin 10.5t?fuel usage avg 10.4t per hour

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68
Q

Cathay Pacific

What is the MTOW of 747-400?

A

396 tons

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69
Q

Cathay Pacific

Weather conditions with regard to position of typhoon

A

Winds & worst wx is most extensive in:Sth hemisphere =LH front quadrantNth hemisphere = RH front quadrantWhy? This is where the forward motion is added to the rotational speed of the cyclone

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70
Q

Cathay Pacific

How can you tell the difference between a 747-400, 747-400F and the 747-400BCF / special freighter model?

A

All the freighters are silver (polished aluminium with minimal paint)The BCF / special freighter has windows blanked out and the hump is slightly longer than the 747-400F.

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71
Q

Cathay Pacific

Explain VMCA

A

The minimum airspeed at which when the critical engine is suddenly made inoperative, it is possible to recover control of the aeroplane and maintain straight flight.Conditions:MTOWMax aft CofGGear upFlaps in takeoff config

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72
Q

Cathay Pacific

Would you takeoff with frost on the underside of the wing?

A

In no circumstances should a formation of ice or frost be allowed to remain on the wing surfaces prior to takeoff.

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73
Q

Cathay Pacific

What are the VMCG considerations for operations on gravel?

A

VMCG may be increased due to the wheels in contact with gravel LESS able to resist the yawing moment (as compared to a sealed surface)

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74
Q

Cathay Pacific

Explain FANS & ACARS?

A

FANS is the Future Air Navigation System. If all the elements were implemented, it would offer reduced separation / reduced fuel burn etc for airlines.ACARS (one element of FANS), a digital data network using aircraft VHF and/or HF radio to transmit/receive data from/to airline operations.

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75
Q

Cathay Pacific

Tell me about the LE flap devices on an A340 compared to the 747.

A

The A340 has LE slats with a slot which allows high pressure air to bleed from the bottom of the wing to the top (re-energises boudary layer).The B747 has inboard Kruger and outboard VCLEF’s.Both delay separation of the airflow at high angles of attack, reducing stall speed & allowing for reduced takeoff & landing speeds.

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76
Q

Cathay Pacific

What devices/features are fitted to an A340 to stop the traditional swept wing nose pitch up at the stall?

A

Prevention of stall in the first place through protections provided by flight control laws. (Eg Alpha Floor)Washout to reduce AOA at the wing tips and prevent the tips stalling first.

77
Q

Cathay Pacific

What happens to the relative AoA when Krueger flaps are fitted? How does this effect the stall qualities vs the rest of the wing?

A

Reduces the angle of attack(?)747 Kruger flapswill stall first before the outboard VCLEF’s, as VCLEF’s will stall at a higer AOA due to the small slot.

78
Q

Cathay Pacific

How do we determine/calculate when an aircraft will aquaplane?

A

Quoted rotating and non-rotating calcs ie takeoff vs landing. Rotating (takeoff) = 9 x SR of tyre px and Non-rotating (landing) = 7.7. The aircraft will continue to aquaplane to a much lower speed once it’s started.

79
Q

Cathay Pacific

What’s the tyre pressure of an A340?

A

225psi.

80
Q

Cathay Pacific

Tyre pressure = 225 PSI.So when will it aquaplane then?

A

√225 = 15.Therefore 15 x 9 = 135kts (rotating).

81
Q

Cathay Pacific

Tell me about aquaplane speeds vs approach speeds for landing.

A

Firmer landing technique and spoilers deployed on landing would increase aircraft weight and reduce aquaplaning. Mention not to grease the landing on.

82
Q

Cathay Pacific

You select reverse thrust on landing and the aircraft starts to yaw (rwy still wet). What could casue this, and what do you do?

A

Could be caused by a crosswind landing on a contaminated runway. If the aircraft touches down with some crab or is allowed to weathercock into wind after landing, the reverse thrust side force component and the crosswind component cancombine to cause the aircraft to drift to the downwind side of the runway.reduce reverse thrust to reverse idlerelease the brakesuse rudder & differential brakingWhen re-established on centerline, re-apply braking and reverse thrust as required.

83
Q

Cathay Pacific

What percentage of thrust is generated by the N1 fan?

A

N1 measures the rotational speed of the low pressure turbine shaft.In a high bypass turbofan engine, thrust output from the by-pass fan air can be approximately 75%

84
Q

Cathay Pacific

Let’s compare the Metro wing to the 747 wing. Why do you think they are so different?

A

Metro has a high aspect ratio, tapered, non-swept with no dihedral.747 wingSweptDihedralTaperedDifferences:higher speedhigher altitudeturbojet vs turboprop engineslonger range & larger fuel capacitylarger load to support

85
Q

Cathay Pacific

Look behind you (airport). You are about to takeoff on RWY 25 in a 747 and the wind is from the right. Which is the critical engine? Why?

A

Number 4 (upwind) engine is the critical.It provides the biggest yawing moment (to the left),that counteracts the yaw to the right caused by the crosswind.

86
Q

Cathay Pacific

Why is the #2 engine always the critical engine in the Metro?

A

Metro 23 prop blades rotate clockwise when viewed from the front.Due to asymetric blade effect, or ‘P’ factor. The downgoing blade has a higher angle of attack than the upgoing blade.The engine with thrust that is furthest from the centreline will have the greatest yaw effect, and therefore the opposite is the critical engine.

87
Q

Cathay Pacific

If I told you there was a typhoon over Singapore would you be surprised? Why?

A

Yes. Typhoon’s generally form between 5-15 degrees of the equator. Rarely form with 5 degrees because coriolis force is weakest at the equator.Note: However, Dec 26 2001, tropical storm / typhoon Vamei formed at 1.5 degrees North.

88
Q

Cathay Pacific

What is a typhoon?

A

A typhoon forms initially as a thunderstorm, from a low pressure sytem in tropical waters, and feeds on the latent heat release as moist air rises.Coriolis force initiates cyclonic rotation. This acceleration causes them to turn toward the poles.Water temps > 26.5CWam water currents > 50m depth

89
Q

Cathay Pacific

You are flying finals into HK – in your Metro - your own aircraft type. There is windshear and down low at 100’ you are experiencing IAS fluctuations of ± 15kts. What would you do?

A

Follow Metro windshear procedure:Apply max powerEnsure wings level (unless for terrain avoidance)Up to 18degs pitch (intermittant stick shaker)No reconfiguration or increase in airspeed until terrain clearance is assured

90
Q

Cathay Pacific

You are flying finals into HK in a 747. There is windshear and down low at 100’ you are experienceing IAS fluctuations of +/- 15kts.What would you do?

A

Windshear procedure (A320)TOGAAutopilot keep onSRS pitch orders follow rapidly & smoothlyConfig no changeMonitor flight pathRecover smoothly

91
Q

Cathay Pacific

What do winglets do?

A

Reduce drag.They diffuse the strong vortices released at the tip and optimise the spanwise lift distribution, while maintaining the additional moments on the wing within limits.747-400 suffers 2.5% drag loss without winglets (= 9.5 tons at takeoff)

92
Q

Cathay Pacific

Why doesn’t the 777 have winglets?

A

The 777 has a ‘super-critical’ aerofoil that doesn’t need winglets.Most of the lift is produced from the reflex camber on the undersurface (to compensate the loss of camber on the upper surface)The gain from winglets on this aerofoil is very small, and would make the aircraft too large for a standard airport gate.

93
Q

Cathay Pacific

What happens to the drag curve as your weight reduces?

A

The total drag curve moves down and to the left. At light weights both range and endurance are increased.However, to maintain the optimal angle of attack, airspeed must be reduced.

94
Q

Cathay Pacific

How do slotted flaps work?

A

A slot betwen the flap and the wing enables high pressure air from the under-surface to re-energise the boundary layer over the flap.This helps the airflow to stay attached to the flap, delaying the stall.

95
Q

Cathay Pacific

What engine is on the 747-400 and how much thrust?

A

RB211-524H-T60,600 lbs thrust

96
Q

Cathay Pacific

What is the ITCZ?

A

Near the equator, the Northeast and Southeast trade winds converge in a low pressure zone known as the ITCZ.Produces thunderstorms and heavy precipitation. Its position varies with the seasons, and whether over land or water.Flight hazards include icing, turbulence, lightning & windshear. Widespread Cb’s, tops to 55,000’, andthe ITCZcan be as wide as 300nm.

97
Q

Cathay Pacific

How would you handle landing during a Typhoon including go around procedures?

A

Hazard considerations include high winds, heavy precipitation, low vis, thunderstorms, windshear, lightning strike, microburst, turbulence, contaminated runway surface.Go-around considerations would be to ensure the landing weight does not exceed that at which the minimum OEI MAP gradient can be achieved.

98
Q

Cathay Pacific

Cathay - how many aircraft and what types (pax fleet)?

A

747-400 23777 2/300 25A340 3/600 17A33027Total fleet of 116 wide bodied a/c

99
Q

Cathay Pacific

Difference between RB211 and Trent?

A

RB211 was superceded by Trent in the 90’sBoth have 3 spool configurationEach model is scaled to meet a wide range of performance & thrust requirements

100
Q

Cathay Pacific

What unit of thrust measurement on RR/CFM engines?

A

RR uses EPRCFM uses N1

101
Q

Cathay Pacific

How to measure EPR?

A

EPR is the ratio of the core engine exhaust pressure compared to thecompressor inletpressure.IEPR is the ratio of the core engine exhaust pressure and the fan discharge pressure, compared to the compressor inlet pressure.

102
Q

Cathay Pacific

Why EPR or N1?Which is better?

A

EPR is meant to be proportional to thrust throughout engine life. This is not true on N1, where blade degradation and engine wear means that for a constant N1, actual thrust may reduce as the engine ages.However:Icing can significantly effect EPREPR is not a linear indication of thrust

103
Q

Cathay Pacific

Fuel in the horizontal stab? and why?

A

More fuel = greater rangeFuel in stab = rearward COG, therefore less downward force on the elevator required, less drag and increased performance.

104
Q

Cathay Pacific

FL350 temp = -50.What is theISA deviation?

A

ISA @ FL350 = (15-(2x35))= -55oCTherefore temp is ISA +5

105
Q

Cathay Pacific

CFIT - How do we prevent CFIT accidents?

A

CFIT usually happens in the approach/landing phase,and 2/3 of accidents occuring within 8nm of the airfield (usually in line with the runway). Caused by a lack of vertical situational awareness. Many CFIT accidents occur with a non-precision approach such as VOR/DME.Can help to prevent with:technology (EGPWS / TAWS, autoflight)training (TAWS escape manoeuvere)SOP’s (stabilised approach, briefings & callouts)Effective CRM

106
Q

Cathay Pacific

GPWS inputs & difference between GPWS and EGPWS?

A

GPWS inputs:Barometric pressure changeILS GSRadar AltimeterConfigurationEGPWS gave the system a improved forward looking capability, by combining a worldwide terrain database with GPS. It provides more warning time, and also warns against flying into terrain away from a runway.

107
Q

Cathay Pacific

Selection of TA (only) on the TCAS after engine failure. Why?

A

Because the aircraft with OEI may not be capable of the performance required to carry out the avoidance manouveredirected by a RA.

108
Q

Cathay Pacific

Why do we have Carbon brakes on the 747-400?

A

40% lighter (saves up to 1800lbs on 747)last longer (2500-3000 vs 2000)can be refurbishedabsorb more heatwear according to number of applications (not sever

109
Q

Cathay Pacific

Explain how a VOR works?

A

The VOR transmits two signals, a reference phase and variable phase. The variable phase rotates (electronically) at 1800rpm.The phase relationship is used to compare the two signals to establish what radial the user is on, using magnetic North as the baseline.

110
Q

Cathay Pacific

Explain how GPS works?

A

The basic principle is to establish the receivers distance from a minimum of four orbiting satellites, by determining the time taken for the signal from each satellite to reach the receiver.By knowing the range from four satellites, a position fix can be made.

111
Q

Cathay Pacific

How many Satellites do we need for a 3D position? And for RAIM?

A

4x sat’s req’d for an accurate 3D fix5x sat’s req’d for RAIM

112
Q

Cathay Pacific

Why are there winglets on the 747-400 and not on the 747 Classic?

A

747-400 used on ULH extended range operations, so a small increase in efficiency provides a worthwhile gain.Classic’s used mainly as freighters where uplift is the main priority, and a fuel stop (such as ANC) is the norm.

113
Q

Cathay Pacific

Why do we have swept wings on jet aircraft?

A

To delay the onset of compressibility effects (Eg delay Mcrit). The aircraft is able to fly faster before the top surface accelleration produces shockwave,which significantly increases drag.How? By reducing the effective chordwise component of the airflow.

114
Q

Cathay Pacific

What engines do Cathay Pacific’s’ 747-400’s have?

A

RB211-524 HT

115
Q

Cathay Pacific

What engines do Cathay Pacific’s’ Airbus 340’s have?

A

A340-300 = CFM56-5C4A340-600 = Trent 500

116
Q

Cathay Pacific

What can you tell me about the RB211?

A

It is a family of high bypass, turbofan engines made by RR.RB211-524H-TTriple spool high bypass ratio1/7/6 wide chord fan, IP, HP compressor1/1/3HP, IP, LP turbineSingle annular combustor

117
Q

Cathay Pacific

How is the RB211 started?

A

Pull start switch. Opens start & engine bleed air valves. Duct pressure will increase as the APU provides bleed pressure to the engine. The start light illuminates.At 10% N2, fuel control switch to RUNStarter cutout occurs at 50% N3. Start switch is released to the in position, start & bleed air valves close, start light extinguishes and ignition discontinues.Monitor start until engine stabilised

118
Q

Cathay Pacific

When would you use engine anti-ice?

A

In visible moisture with an OAT of +10oC or less

119
Q

Cathay Pacific

How would using engine anti-ice affect fuel consumption?

A

Engine anti ice increases fuel consumption.

120
Q

Cathay Pacific

What is Dutch roll?

A

Dutch roll is a coupled lateral-directional oscillation, which is usually dynamically stable but is objectionable due to the oscillatory nature.It is a characteristic of a/c with stronger lateral than directional stability.The response of the aircraft to a disturbance from equilibrium is a combined rolling-yawing oscillation in which the rolling motion is phased to precede the yawing motion

121
Q

Cathay Pacific

Does VMCG change with a change of C of G?

A

A rearward C of G reduces rudder authority, and therefore would increase VMCG.

122
Q

Cathay Pacific

Is a forward or rearward C of G better for fuel economy and why?

A

Aft C of G increases fuel economy. The wings of a conventional aircraft generate a nose down pitching moment. To balance this a download is required on the tail.An aft C of G, requires less download on the tail, which produces less negative lift, effectively reducing the weight of the aircraft and increasing cruise performance.

123
Q

Cathay Pacific

Explain Mach tuck.

A

As an aircraft approaches its Mcrit, it experiences an increasing nose down pitching moment. This is due to:Shockwave effects experienced at the thick wing root first. Results in rearward movement of CPReduced download on the tailplane due to changing downwash from the wing due to upper surface flow separation

124
Q

Cathay Pacific

What happens to stall speed at high altitude?

A

Increases

125
Q

Cathay Pacific

What type of engine does the Metro 23 have?

A

Garrett TPE331-12UAR, rated at 1100 shp.

126
Q

Cathay Pacific

What are some disadvantages of having winglets?

A

Increased weightIncreased wing bending momentFor new designs, it requires a stronger, heavier wingRetrofit may require changing the operating conditions to lower the wing loading

127
Q

Cathay Pacific

Why does the 747-400 have swept wings?

A

For high altitude, high speed flight. A swept wing raises Mcrit to a higher value.It does this by reducing the effective chordwise component of the airflow.This means buffet, drag rise and control and stability problems are all deferred to a higher Mach number.

128
Q

Cathay Pacific

What is Krueger flap?

A

A high lift leading-edge device usually found on the inboard section of the wing.It increases lift by increasing the wing surface area and camber, and also increases lift by enabling a higher AOA to be obtained.

129
Q

Cathay Pacific

What is Fowler flap?

A

A flap that increases surface area and camber, by extending down and to the rear of the wing. Usually on a track system such as a C172.

130
Q

Cathay Pacific

What is windshear?

A

Is a sustained change (lasting more than a few seconds) in headwind or tailwind resulting in changes in the liftto the aircraft. Changes in 15kts or more is considered significant. May be caused by:microburstthunderstorm gust frontsea breezeflow past terrain

131
Q

Cathay Pacific

Tell me about the monsoon.

A

Monsoons are large scale wind systems caused by differences in the temperature of land and sea over the seasons.In HK during Summer, intense solar heating of the Asian land mass, forms a semi-permanent low pressure area near the heart of the continent. Warm and moist air from the Indian ocean and the South China sea flow into this low pressure area, and deposit heavy rainfall during May-Sept.Summer monsoons in HK typically blow from the South West.

132
Q

Cathay Pacific

Coulda typhoonform over the Gobi desert?

A

No

133
Q

Cathay Pacific

Tell me about GPS/DGPS.

A

DGPS or differential GPSis regular GPS with additional correction signal added. This correction signal improves the accurace of the GPS and can be broadcast over any authorised communication channel.Accuracy improvement down to 10mtrs.

134
Q

Cathay Pacific

What are the errors in the GPS system?

A

The largest error was caused by ‘Selective Availabilty’, but this was switched off in 2000.Errors:Satellite geometery - GDOPEphemeris data (errors in transmitted location of satellite) & clock driftMultipath effectAtmospheric effectsReceiver

135
Q

Cathay Pacific

How does an INS work?

A

INS consists of a computer and 6 accelerometers, mounted on a gyro stabilised platform.Once provided with an initial position, it computes its own updated position from the motion sensors.

136
Q

Cathay Pacific

Where does a swept wing stall first, and what happens to the CP?

A

Will stall at the tips first. Due tohigh wing loading at tips from taperswept wing produces strong cross flow of boundary layer at high coefficients. Results in low energy boundary layer at the tips that is easily seperatedStalling at the tips will cause the CP to move forward, and this is the cause of the nose up pitching moment.Note: An unswept wing CP moves forward approaching the stall, then aft, after the stall

137
Q

Cathay Pacific

What do aircraft designers incorporate into the wing design to reduce tip stall on a swept wing?

A

Washout (and vortex generators?)

138
Q

Cathay Pacific

Describe fuel management in the A340?

A

Normal OperationFuel is always fed to the engines from the inner tanks.The fuel transfer sequence is as follows:Center to the inner tanksInner tank empties down to 4000kgsTrim to the inner tanksInnerempties down to 3500kgsOuter to the inner tanksThe trim tank transfer system controls the aircrafts CGThe system either transfers fuel to the trim tank (aft transfer) or from the trim tank (fwd transfer)This movement of fuel changes the aircraft’s CGWhen the aircraft is in cruise, the system optimises the CG position to increase fuel economy by reducing dragNormal operation is automatic, but the crew can manually select a fwd fuel transfer

139
Q

Cathay Pacific

What is the effect of an aft C of G when flying for range?

A

An aft CoG is provides a greater range due to:less download on the tailless effective weightimproved cruise performance

140
Q

Cathay Pacific

Explain Vmcg and Vmca?

A

VmcgThe minimum airspeed at which takeoff can be continue using aerodynamic controls aloneAssumes:critical engine failedremaining engine at takeoff thrustVmcaThe minimum airspeed at which it is possible to maintain directional control when airborne:following failure of the critical enginewhilst employing full rudder deflection

141
Q

Cathay Pacific

How can you increase the BRW on a Vmcg limited take off?

A

By limiting thrust.

142
Q

Cathay Pacific

What do you know about Carbon fibre brakes?

A

Pro’s:Up to 40% lighter (1800lbs less on 747)Wear based on the number of applications (not severity)Last longer (2500-3000 vs 2000)Can be refurbishedAbsorb more heatCons:More expensiveMust be careful during taxi to avoid unecessary wear

143
Q

Cathay Pacific

What do you know about aquaplaning?

A

3 TypesTypePrerequisiteDynamicStanding water on the runwayTyre is completely lifted off the runway and supported by the waterViscousSurface is damp and there exists a very thin film of fluid which cannot be penetrated by the tyre. Wheel free to rollReverted rubber skidding:The heat from friction between the runway and the tyre causes the rubber to become tacky, the water boils & steam prevents the tyre from contacting the runway.Locked wheel

144
Q

Cathay Pacific

Can aquaplaning occur on take off as well as landing?

A

Yes. Happened to A320 when it’s nosewheel aquaplaned on takeoff from Melbourne in 1998.

145
Q

Cathay Pacific

What is a microburst?

A

Strong concentrated downburst of air from the base of a convective cloud.Often associated with squall lines, thunderstorms and virga.

146
Q

Cathay Pacific

Explain windshear in a microburst?

A

Up to 6000fpm (60kts)seldom lasts more than 15-20 minsless than4km wideProfile:Airspeed increaseAirspeed decrease (rapid)Rate of descent increase

147
Q

Cathay Pacific

What sort of considerations might you give to operating in and around a typhoon? (Taxi / Take off / Landing)

A

Heavy precipitation (low vis)Contaminated runwayWindshearThunderstorms

148
Q

Cathay Pacific

What is asymmetric blade effect?

A

The downgoing blade has a higher AOA and therefore produces more thrust.The downgoing blade that is furtherst from the centreline will have the greatest yawing moment during asymmetric flight.Thus, the failure of the other engine is less desirable, and therefore it is known as the critical engine.

149
Q

Cathay Pacific

Is there a critical engine on a jet? Why?

A

Yes, the upwind outboard engine due to controllability problems such as with a crosswind take off.

150
Q

Cathay Pacific

Explain each take-off segment with each climb gradient.

A
151
Q

Cathay Pacific

What is the most critical segment for your aircraft?

A

A

152
Q

Cathay Pacific

What is the relationship between V1 and VMCG?

A

VmcgThe minimum airspeed at which takeoff can be continue using aerodynamic controls aloneAssumes:critical engine failedremaining engine at takeoff thrustV1 is the decision speed in the event of an engine failure on take-off, at which the take-off may be either abandoned or continured.V1 can never be less than Vmcg

153
Q

Cathay Pacific

Why is tip stall bad?

A

Tip stall on a swept wing aircraft will move the CP forward, which produces a nose-up moment, which will exacerbate the stall.

154
Q

Cathay Pacific

How does sweep effect lift, and how do designers counteract this?

A

Produces less lift, especially at low speeds.High lift devices incorporated such as LE slats / flaps, and trailing edge flaps.

155
Q

Cathay Pacific

In long haul jet transporters they have rear fuel tanks. Why is this?

A

More fuel equals more range and weight in the tail.This will result in a more rearward CoG, reducing tailplane downforce, total drag, and ultimately a reduced fuel burn.

156
Q

Cathay Pacific

Talking about range versus endurance. Why would we fly at best endurance?

A

For holding.

157
Q

Cathay Pacific

For jet transport aircraft set up in long range cruise what happens to speed?

A

LRC provides time savings for minimal increase in fuel consumption.Gradual reduction in cruise speed as gross weight decreases with fuel burn off.Higher speed than max range speed.

158
Q

Cathay Pacific

Why would we fly at best range?

A

When you want the most miles for a given amount of fuel.Perhaps when unanticipated headwinds have eaten up margins and getting close to minimum reserves.

159
Q

Cathay Pacific

What speed isbest rangein relation to best endurance?

A

Best range is slightly up and to the right on the drag curve.Eg slightly faster. 1.32Vmd

160
Q

Cathay Pacific

If ATC asked you to hold above FL140 in terminal airspace what would you do?

A

Setup for max endurance speed.

161
Q

Cathay Pacific

On a double bogie assembly which brake would get hottest? Why?

A

Rear wheels suffer reduced braking efficiency as they receive less airflow,andwhat airflow they do receive is already heated from the brakes in front.

162
Q

Cathay Pacific

How can we estimate if there is a danger of aquaplaning on a runway when landing?

A

By using the formula (9x sq root of the tyre pressure), and checking for standing water at destination runway.

163
Q

Cathay Pacific

How does a GPS work?

A

Consists of three major components:Space: 24x satellites, orbiting @ 10,900nm. Operating in 6 orbital planes, with a 12hr period.Control: 5 monitoring station + 1 master controlUser: Antenna + receiver processorPosition is calculated by measuring elapsed transit time of signal and calculating range to satellite.3x Satellite for a 3D fix4x Satellite for RAIM

164
Q

Cathay Pacific

Do you know of INS and IRS? What is the difference?

A

INS is a collection of components that togetherare a system that is able to provide navigation computations and solutions.IRS is differerent in that it is a single box that contains an Inertial Reference Unit and a computer to produce reference information. This information is then provided to numerous other aircraft systems and displays.

165
Q

Cathay Pacific

In an INS what is a Shuler’s loop?

A

Schuler tuning is the torqueing of the gyros in an INS, to take into account the curved flight path of an aircraft as it follows the earth’s surface.

166
Q

Cathay Pacific

In jet transporters they have Yaw dampers. Why?

A

To counteract the dutch roll tendency of the swept wing.

167
Q

Cathay Pacific

How does a Series yaw damper work?

A

The damper is built into the rudder control system so that it applies inputs to the rudder, but the pedals do not move.Can be used for take off and landing. Found on newer aircraft and jet transports.

168
Q

Cathay Pacific

Describe the pressurisation system on the Metro.

A

It uses bleed air via the airconditioning system to pressurise the cabin.The outflow valve controls the flow of air out of the pressure vessel. The valve responds to commands by the pressurisation controller through a pneumatic relay

169
Q

Cathay Pacific

What is the normal differential limit on the Metro?

A

7.0 PSI

170
Q

Cathay Pacific

On the Metro how is the air coming into the cabin is cooled?

A

Air is cooled by an air cycle machine.Bleed air passes through the heat exchanger, strikes the cooling turbine wheel, then vents overboard.The turbinedrives the impeller, which then draws ram air over the heat exchanger, cooling the bleed air.

171
Q

Cathay Pacific

What sort of de-ice/anti-ice systems does the 747 have?

A

EATWEAPLDEngine spinner (inertia)APU inlet heated (bleed Air)Toilet service/dump electric heatedWindshield heat.Engine inlets (Bleed Air)Angle of attack/stall warningPitot/Static probesLeading edge, wing only (bleed Air) no tail?Drain mast/s

172
Q

Cathay Pacific

Which components of the 747 anti-ice system use bleed air?

A

Engine inletAPU inletWind leading edge

173
Q

Cathay Pacific

Would that affect engine performance? If so how?

A

Yes, reduced performance as bleed air is drawn from the HP compressor stage/s

174
Q

Cathay Pacific

What de-ice/anti-ice systems does the Metro have?

A

Oil cooler inlet duct (elec)Propellers (elec)SAS/Pitot head (elec)Windshield (elec)Engine nacelle inlet (elec)Boots wing / stab (elec)

175
Q

Cathay Pacific

What is TCAS?

A

Traffic alert and collision avoidance system. TCAS alerts the crew to traffic that may present a collision threat and provides the crew with a vertical avoidance manoeuvere.TCAS uses mode S transponder to interrogate the transponders of other a/c in the vicinity.Generates TA when 40secs from closest point of approach.Generates RA when 25secs from closest point of approach. RA provides a vertical restriction or manoeuvere to maintain or provide seperation.

176
Q

Cathay Pacific

How do we set thrust on the B747?

A

EPR

177
Q

Cathay Pacific

Do we still need to know how fast the fan is spinning if we set EPR?

A

Yes to ensure limits are not exceeded.

178
Q

Cathay Pacific

How many fuel tanks doesthe B777have?

A

Center tank2x main tanks (1 per wing)some models have Aux tank

179
Q

Cathay Pacific

B747, can you move the fuel from the forward tanks back into the stabiliser tank?

A

No, the 747 stab tank is just somewhere to store extra fuel; it was never designed to be a trim tank.Stab fuel in the 747 is burned fairly early in long range flight, due to aft CofG concerns following failure of the stab tank xfer/jettison pumps and the inability to use any of the now trapped stab fuel.

180
Q

Cathay Pacific

If you could move fuel from the forward tanks back to the stabiliser tank, what would be the advantage of doing this?

A

For use as a trim tank, such as on the A330/A340. Would generate a more aft CofG, less tailplane down force, and thus improved cruise performance / reduced fuel usage.

181
Q

Cathay Pacific

Why would the C of G be ahead of the C of P?

A

For an aircraft to return to its trimmed attitude, without input from a pilot or autopilot, it must have a positive longitudinal static margin.The longitudinal static margin is the distance aftwards from the center of gravity (or mass) and the center of pressure.The center of pressure must lie behind the center of gravity for a positive static margin and static stability. If the center of pressure is ahead of the center of gravity, active inputs to the control surfaces are required to maintain stable flight.Ultimately, the position of the center of pressure relative to the center of mass determines the stability, required control inputs, and controllability of the vehicle.

182
Q

Cathay Pacific

What sort of flaps does the Metro have?

A

Double slotted fowler flap.

183
Q

Cathay Pacific

How are the flaps powered on the 747-400?

A

Leading edge = pneumaticTrailing edge = hydraulic

184
Q

Cathay Pacific

Can you see any differences with hydraulic power versus electrically powered flaps?

A

A

185
Q

Cathay Pacific

What sort of brakes does the Metroliner 23 have?

A

Manual hydraulic disc brakes. Consists of six pisotns that force brake linings against a wheel driven rotating disc.

186
Q

Cathay Pacific

Do carbon brakes wear more when they are cold or hot?

A

Carbon brake wear is dependant upon the number of applications, not the severity.In conclusion, high braking pressure leads to a lower brake wear, but only up to a limit. The lower brake wear is due to the formation of the silicon film at high energy braking which serves as a lubricant and protector of the ceramic/carbon brake material. Re the formation mechanism of the film - it is known that it does not form at low energy braking, and it is destroyed at extremely high energy braking.

187
Q

Cathay Pacific

What’s the most important instrument when encountering windshear?

A

VSI

188
Q

Cathay Pacific

What code do you set on the transponder for radio failure?

A

7600

189
Q

Cathay Pacific

How does a Parallel yaw damper work?

A

The damper is integrated with the rudder control system so that it applies inputs to the rudder and the rudder pedals move.Must be switched off for take off and landing &engine failure.

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