Interview Questions

Front 1

Explain all 3 lines on the L over D chart -

Back 1

CL - measure of the aerofoil ability to produce lift (critical 16 deg)
CD - measure of the aerofoil ability to produce drag (parasite + induced)
L/D - aerofoil efficiency max at 4 deg
- min L/D is best endurance (min power = best range)

Front 2

Using an aircraft model, explain Dutch Roll -

Back 2

- lateral stability (roll) stronger than directional stability (yaw)
- stability is the tendency to return to original position after disturbance
1. A/C rolls left
2. A/C sideslips left (due L&W not directly opposed)
3. RAF from the left, A/C yaws left
4. Wings level right (strong lateral)
5. A/C sideslips right etc.

Front 3

Lateral stability increased by -

Back 3

-dihedral wings (increase A/A on downgoing wing = increase lift)
- sweepback wing (downgoing wing more lift due more span +aspect ratio to RAF)
- high keel (high fin, T-tail or high wing), low CG

Front 4

Directional stability increased by -

Back 4

- large fin area and keel
- long moment arm (from CG)

Front 5

What can cause Dutch Roll?

Back 5

- use of rudder at high subsonic Mach
- turbulence

Front 6

Explain yaw dampers and why a/c would have more than 1 -

Back 6

- small control surface driven by rate gyro (on rudder)
- prevent/min unwanted yaw
- 2; one for upper, one for lower surface. Seperate couple for redundancy
- usually limited movement to prevent full rudder deflection in malfunction
- autopilot requires 1 before can be engaged

Front 7

IAS vs. TAS in a climb - bigger, lesser or same?

Back 7

- climb at fixed IAS, Mach + TAS increase
-climb at fixed Mach, IAS + TAS decrease
- SoS slower in cold air (climb)
- SoS constant in troposhere (36,000ft)

Front 8

What do vortex generators do at low airspeed? How do they help?

Back 8

- energize boundary layer, cause turbulent layer
- produces more drag, less lift but remains attached at high A/A
- good for a/c that cruise at low IAS so moderate A/A

Front 9

What happens to Mach if you climb at a constant IAS?

Back 9

- altitude increases, TAS increases due less density
- as alt increases SoS decreases due cold air
- Mach INCREASES

Front 10

What are the advantages of aft CG?

Back 10

- less L+W nose down couple
- less downforce needed by stabilizer
- less A/A, less drag = increase range, speed, endurance

Front 11

What type of engines does the CX B747 have?

Back 11

RB211-524G/H-T

Front 12

Tell us about the RB211 and RB211-524 -

Back 12

- RR 1st 3 spool engine
- 524G/H more thrust
- G = 58,000lb
- H = 60,600lb
- redesigned fan and IP compressor
- 1st to feature Full Authority Digital Engine Control
- Trent = better HP compressor, lighter, fuel effecient, less emissions so -T series

Front 13

What is Hong Kong's location?

Back 13

22 deg 20 min N
114 deg 11 min E

Front 14

Explain the benefits and attributes of horizontal stab fuel tanks -

Back 14

- Airbus: trim fuel
- decrease cruise drag by moving CG (disadvantage = weight + complex in failure)
- in climb fuel aft = nose up attitude, less downforce
- in descent fuel forward = slow speeds, nose down, easier to manouevre (stall recovery)
- Pros: manipulate CG directlly, change CG with little mass movement, CG close to optimum

Front 15

Explain why swept wings -

Back 15

- delay effects of compressibility (shockwaves, drag)
- allows cruise at higher Mach
- increases lateral stab
- less lift, higher max A/A so lower drag

Front 16

Limitations of swept wings -

Back 16

- change in tip flow direction = reduce effective angle
- flow compression at wing root = more drag than theoritical

Front 17

Disadvantages of swept wings -

Back 17

- lower increase in lift, higher stall angle
- high drag at high A/A, boundary layer seperation (control: slats/slots, vortex gen, saw tooth)
- high min drag (speed brake)
- tip stalling (wash out, boundary layer control)
- deep stall (pusher/shakers)

Front 18

Why do wing tips stall first on swept wing?

Back 18

- all aerofoil have tendency to stall tip 1st
- swept wing lateral and LONGITUDINAL controls difficult
- CP moves up wing (towards root) = smaller moment between CP and CG, less manourverable

Front 19

What kind of flaps does the B747 have?

Back 19

- Triple slotted trailing edge (fowler??): increases chord then camber
- slots directs HP from under wing to remain attached to flap = lift
- Krueger flap; hinged at LE from UNDER surface wing. Increase camber and max CL

Front 20

What types of flaps are there?

Back 20

Plain, slotted, split, fowler, zap, krueger

Front 21

What a/c do we use from JFK to HKG?

Back 21

B777-300ER to North America (New York)

Front 22

Where are JFK, O'Hare, LAX and SFO international airports?

Back 22

New York, Chicago, LA, San Francisco

Front 23

Explain ETOPS -

Back 23

- Extended-range Twin-engine Operational Performance Standards
- allows twin airliners (A330, A350, B777) to fly long distance routes.
- refers to SE flight times between diversion airfields (if more than 60 min)
- now 180 max at entry to service
- extended to 240min case by case (+probation 24 mths etc.)
- A350 plan on 350min, B777 330min
- 2 stages: 1. type approval, 2. Operational certification (based on operator)

Front 24

Explain the fuel system on the A330 -

Back 24

- A330/A340 fuel transfer between wing+centre tanks and fuel tank in horizontal stab (by FADEC)
- optimize a/c CG for cruise
- CG trimmed with fuel weight, rather than drag inducing aerodynamic trims in elevators

Front 25

Population of HK?

Back 25

7 million

Front 26

Where does CX fly in North America?

Back 26

Vancouver, Toronto, New York, Chicago, LA, San Francisco

Front 27

What's the name of CX first a/c?

Back 27

'Betsy'- retired in 1955, found 30 years later in Aus.
- HK science museum

Front 28

When is CX anniversary?

Back 28

24 September 1946 (66 years old this year)

Front 29

Who were the founding members of CX?

Back 29

- American: Roy C Farrell
- Australian: Sydney de Kantzow

Front 30

How many days a month would you expect to fly?

Back 30

SO = 12 rostered days a month
- 21 days annual leave

Front 31

CX is not really a global airline, what continent don't we fly to?

Back 31

Antartica!
- Others: Asia, Europe, Australia, Africa, North America, South America

Front 32

What percentage of HK is chinese?

Back 32

95%
- Other: Filipino, Indo, Westerners, Indian, Nepalese, Japanese, Thai, Pakastani

Front 33

What is Fly-by-wire?

Back 33

- movements of flight controls converted to electronic signals by wires
- flight computers determine how to move actuators to provide ordered response
- auto stability (gyros with sensors)
- quadruplex for redundancy
- weight saving, smaller stabilizers
- Airbus A320 1st all digital airliner
- B777 1st boeing. Yoke visual feel. Will operate outside limits in emerg.