Aerodynamics and Systems Flashcards
When the bank angle increases to 60 degrees, what happens to G force and stall speed?
G force approx 2 G
Stall up about 40%
Where does weight act through?
Centre of gravity
Where does lift act through?
Centre of lift
What happens if centre of lift is ahead of centre of gravity?
Aircraft suffer nose up pitch
What happens if centre of lift is behind centre of gravity?
Aircraft suffer nose down pitch
Longitudinal stability is about what plane?
Pitching plane
Lateral stability is about what plane?
Roll plane
What will increase lateral stability?
Dihedral
Swept back wings
What is dihedral?
Wing tips higher than wing root
What does dihedral do to stability?
Increases lateral stability
What is anhedral?
Wing tips lower than the root
What does anhedral do to stability?
Reduce lateral stability and increase turning stability
What is the chord?
Longitudinal distance between leading and trailing edge
What is the mean chord?
Average length of chord
What is the wing span?
Distance from wing tip to wing tip
What is aspect ratio?
Relationship of span to average chord.
What would a wing look like if it had high aspect ratio?
Long and thin
What would a wing look like if it had low aspect ratio?
Short and thick
What does a high aspect ratio wing do to drag?
Produces less induced drag
What is maximum thickness for aerofoil?
Point on wing where it is thickest.
What is camber?
Relationship between chord and thickness.
What a high camber wing section look like?
Thick wing and short chord
What is mean camber?
Average thickness compared to average chord
What is MAC?
Mean aerodynamic chord.
Position of centre of gravity within an imaginary rectangular wing chord.
What is angle of incidence?
Angle between chord line of aerofoil and fore/aft datum line of aircraft
What is angle of attack?
Angle between chord line and relative airflow
What is upwash?
Motion of relative airflow as approaches leading edge
What is downwash?
Motion of relative airflow as it leaves trailing edge
What is the separation point?
Point in front of the wing at which approaching air is separated by approaching wing
What is the boundary layer?
Thin area above surface of wing that is stationary
What does a thick boundary layer do to drag?
Increases drag
What is the transition point?
Flow instability develops.
Turbulent flow starts
Drag increases
What is centre of pressure?
Point through which lift pressure foces act
When is induced drag highest?
Just before the stall.
Also at minimum steady flight
How would we get CAS?
IAS corrected for pressure and instrument errors
How would we get EAS?
CAS less compressibility error
How would we get TAS?
EAS corrected for air density error
What is the biggest influence in the speed of sound?
Temperature
When is speed of sound faster, warm or cold air?
Warm
When at high altitudes and cold temps, what is the speed of sound, faster or slower?
Slower
What is the approx speed of sound?
662 knots
The Mach number defines the relationship between what?
TAS to speed of sound
Mach numbers values are written as a percentage of seed of sound, true or false?
True
If you were flying at the speed of sound, what would the Mach number be?
M1
What happens to TAS if climbing at fixed Mach number?
TAS will reduce
What is Vmo/Mmo?
IAS for max normal operating speed and Maximum Mach normal operations speed
Where would you find figure for Vmo/Mmo?
Flight manual
Vmo/Mmo needle on ASI (known as Barbers Pole)
If you are climbing at IAS just below Vmo, what will eventually happen to Mmo?
Will be eventually exceeded
What is the True OAT always equal to with relation to Total Air Temperature?
Equal to or colder than TAT
What is does Vmcg stand for and what is it?
Minimum control indicated airspeed on ground.
Minimum speed pilot can maintain direction control of aircraft with one engine becoming inoperative during take off roll using aerodynamic controls only.
What aircraft config is found with Vmcg?
Flaps and trim in takeoff config
Critical engine failed
Take off power on available engine
CoG rear
When using Vmcg, what is assumed with the wheels?
Nose wheel no longer on ground.
Main wheels are still on ground
What will forward CoG do to Vmcg?
Lower it
What does a low Vmcg speed do?
Gives us greater asymetric control
What factors will reduce Vmcg?
High density Reduced take off thrust Large tail fin area Large rudder area Forward CoG Short distance from engine to fuselage
What does Vmca stand for?
Minimum control indicated airspeed in air.
What does Vmca assume the aircraft is doing?
Completely clear of ground. Sudden loss of critical engine CoG rear Max available take off thrust remaining engine AoB no more 5 degrees Trim in take off position Out of ground effect Landing gear retracted Windmilling prop Max sea level take off weight
If one engine were to fail, what is the pitching and yawing tendency?
Pitch down
Yaw towards dead engine
What will moving the CoG forward do to controls with one engine out?
Assist with control
What is the critical engine?
Engine that if failed will produce most adverse yaw couple
Down going blade closest to fuselage
To reduce performance loss during critical engine failure, wha should be done?
Slight bank towards live engine
What factors reduce Vmca?
Fuselage mounted engines Reduced thrust Large tail fin area Large rudder area Forward CoG Short distance from engine to fuselage Banking towards live engine High altitude High density altitude Dihedral and fuselage blanket of wing
What is the risk of loss on engine at high altitude?
Aircraft likely to be close to stall speed.
What actions should be taken at high altitude following engine failure
Descent to more suitable engine one level
The area on the aerofoil where smooth streamline airflow beginning to break up and become turbulent is know as what?
The transition point
With increased curvature (camber) of surface what happens to speed and pressure above the surface?
Speed increases
Pressure decreases
(This is Bernoullis theory
What happens to lift as angle of attack increase?
Lift increases until stall AoA then decreases
What does a laminar flow wing do?
Reduces drag, has laminar flow over entire wing (no turbulent flow at all
What are the characteristics of a super critical wing section?
Section thickness and camber further aft
More gradual camber
Reflex curve on underside near trailing edge
What is the primary purpose of super critical wing?
To increase Mach number at which shockwaves form which delays shockwave drag rise
Will aircraft that fly at high Mach numbers be more efficient with swept back wings or straight wings?
Swept back
Where do swept back wings tend to stall first and why?
At the tips.
Air approaching leading edge of wing deflected upwards (upwash)
In swept back wings what happens to the transition point as approaching stall?
Transition point moves forwards and inwards
What is the tendency of the nose during a swept back wing stall?
Nose pitch up
What is generally done to ensure a pitch down at stall?
Washout (twist of wing so incidence angle at tips less than root) Leading edge slat deployment Wing fences Saw/dog tooth Vortex generators Shark teeth
What do leading edge slat devices do?
Extend when within certain AoA/speeds.
Energises the flow over the top surface
Delay break up of streamline flow
Improves aileron effectiveness near stall
What do wing fences do?
Prevent span wise flow.
Rotates opposite direction to usual wing tip trailing vortex
What do leading edge slots do?
Re-energise airflow above wing by injecting high pressure air from below into leading upper surface.
This delays airflow separating into turbulent flow.
Creates greater lift at higher angle of attack
What do leading edge slats do?
Device that moves forward from leading edge to create a slot.
Directs high energy air onto upper wing leading edge to re-energise boundary layer.
Increases camber of wing
Increases stall angle
What does deployment of leading edge slats do to pitch?
Causes a pitch up moment
When are leading edge slats most effective?
High angles of attack
What do leading edge flaps do?
Helps air flow at leading edge overcome early stall
What do Krueger leading edge flaps do?
Increase camber of aerofoil (but dont incorporate a slot)
Increase drag at all speeds
Produces nose pitch up
Increase lift
What do Droop Snoot leading edge flaps do?
Leading edge of wing pivots forward and down to increase camber and wing area which increases lift.
All leading edge devices contribute to lift best at what angle of attack?
High angle of attack
What happens to AoA and approach speed if leading edge devices are not deployed?
Lower AoA
Higher approach speed
What do leading edge flaps do to camber, wing area and stall speed?
Increase camber
Increase wing area
Decrease stall speed
Do leading edge flaps feature slots or re-energise boundary layer?
No
What are the main effect of deploying trailing edge flaps?
Increase camber of wing Increase drag Increase in lift at all AoA Stall AoA reduced Stall speed reduced Nose down pitch
On the wing, what do speed brakes (spoilers) do?
Reduce lift
Creating drag
Providing roll control
Increase descent gradient
What do tail mounted speed breaks do to drag and lift?
Increase drag
Don’t spoil lift
What can be done with spoilers if requiring a roll to the right?
Spoilers on right wing deflect upwards, spoilers on left wing remain down
What happens when the spoilers are set to armed?
Spoilers will raise all spoiler panels automatically when aircraft touches down
Apart from the lift and drag benefits, why use spoilers and inboard ailerons
Helps reduce fatigue on wings/outboard ailerons at high speeds
What is the Critical Mach Number (Mcrit)?
Free stream Mach number at which first shock waves forms
Any part of ac reaches Mach 1 (supersonic)
Marks beginning of transonic range
What happens to drag if you fly faster than Mcrit?
Increase in drag
What is Mfs?
Freestream Mach number
Mach number of aircraft through the air
When do shockwaves form?
After reaching a value greater than mach 1, it reduces back to mach 1, that is when shock wave forms
Where do shock waves tend to form first, thick or thin parts of aerofoil?
Thick
What is the pitch tendency with shockwave?
Nose pitch down
What is the Mach trimmer for?
To counter the nose pitch down tendency after shockwave
What happens to centre of lift with shockwave as speed increases?
Centre of lift moves rearward (pitch down)
What happens to lift and drag after upper shockwave forms?
Lift reduces
Drag increases
What is Mdet?
Detachment Mach number.
When bow shockwaves attach to leading edge
What is all flow above Mdet?
Supersonic
What angles does a normal shockwave form and where?
At right angles to the wing surface
What angles does oblique shock form and where?
Bends backwards on bow wave and tail wave
Why is flying at the aerodynamic ceiling not recommended?
High drag created and significant increase in fuel flow required to maintain speed (reducing range)
Tailplane becomes less effective if stalled
What is Mcdr?
Critical drag rise
Mach number where drag increases significantly due to shockwave formation
Which is higher, Mcdr or Mcrit?
Mcdr
What three things can be done to increase Mcrit and Mcdr values?
Wing sweep
Low thickness/chord ratio
Supercritical wing sections
What speed and altitude is wing sweep most effective at?
High speed
High altitude
Compared to a swept back which, what angle of attack does maximum lift occur on a straight wing?
Less angle of attack
A swept wing has less lift at all AoA than a straight wing, true or false?
True
What does increased sweep do to dutch roll tendency?
Increases it
What does increased sweep do to flap effectiveness?
Decreases it
As Mcrit is reached, what happens to lift?
Peaks just as Mcrit is reached and drops thereafter to M1
What do thin wings do to Mcrit and Mcdr? What about to lift?
Increase Mcrit and Mcdr
Reduce lift
Where is the point of max camber on a supercritical wing?
About 40-45% along
What does supercritical wing do to acceleration of airflow over upper surface?
Reduces it
What do vortex generators do to shockwaves?
Weaken the shockwave that develops and inhibit the thickening of boundary layer behind shockwave.
Increases the Mcdr
What happens in the intake cycle?
Piston moves down
Sucks in mixture of air and fuel
What happens in compression cycle?
Piston moves up
As piston reaches top, spark is supplied which causes ignition of mixture
What happens in the power cycle?
Piston goes down
Explosion/expansion of mixture forces piston down
What happens in the exhaust cycle?
Piston moves up. Expels burnt(spent) fuel through exhaust valve
Describe the BGT and the basic steps of BGT
- At intake end of engine is compressor which is attached to turbine at exhaust end. These are rotating parts of engine
- When rotated, the compressor squeezes air and passes compressed air to combustion chamber
- At combustion chamber, fuel is added and mixture ignited by spark plug
- Explosion causes gases to expand inside combustion chamber
- Expansion converted into velocity through Convergent duct
How much of the energy is required by the compressor to rotate the turbine? How much is used for remaining thrust?
75% rotate
25% thrust
What are some advantages of turbine engines to piston?
Can develop more power and thrust Lighter (better power to weight ratio) More compact Less drag More reliable Cheaper fuel Greater time between overhauls
What is the pure jet type?
Allow all residual gas stream velocity to exit the exhaust
What is the turboprop?
Additional turbines which extract more residual energy and feed it to a prop through connecting shaft
What is the turbofan?
Additional turbines which extract more residual energy and feed it to a multibladed fan through connecting shroud
What is turboshaft type?
Using horsepower from rotating shaft and drive a pump or electric generator to pump fluids or create electricity
What is convergent duct?
Distance across duct narrows
Where is speed greatest in convergent duct?
At narrowest point
At the convergent duct, what is the velocity, pressure and temp?
Velocity increases
Pressure decreases
Temp decreases
At the divergent duct, what is the velocity, pressure and temp?
Velocity decreases
Pressure increases
Temp increases
What is the policy for engine intake anti ice?
Turn on if OAT is +10C or below when operating in presence of visible moisture
What are the advantages of centrifugal compressors?
More robust than axial
Resist damage from foreign objects
Less complex
What are the disadvantages of the centrifugal compressor?
Lower compression ratio
Prone to gas leaks
Prone to compressor surges
What sort of engines are centrifugal type engines suited to, large or small?
Small
What are the advantages of axial flow compressors?
Greater thrust Greater fuel economy Less chance of surging Reduced engine diameter Less drag
What are stators?
Mounted additional blades between each row of the compressor blade that don’t rotate
What do stators do?
Convert increased velocity into increased pressure
Guide gas stream so it’s angle of attack is optimum
When is surging most likely?
Low RPM Thrust opened/ closed too quickly AoA at intake too great Turbulence High altitude Compressor blades damaged Heavy rail or hail Reverse thrust ops Aircraft side slipping
What are compressor stall indications?
Rising EGT
Steadying or reducing fuel flow
Steadying or reducing engine RPM
Engine popping, vibration and banging
How can you cure compressor stall?
Reduce throttle
Lower nose
Increase forward airspeed
What are the advantages of twin spool types?
Develop high compression ratios while reducing compressor stall
Faster spool up times then single
Greater operator flexibility
What are the advantages of 3 spool types?
Shorter in length
Suffer less flexing
Less prone to surging
Spool up fast
What are the advantages of turbofans over pure jet?
Better fuel economy
Reduced noise
Greater thrust
Lighter core components
What are the disadvantages of turbo fans over a pure jet?
Increase drag due to increased frontal area
Increased diameter may affect design of undercarriage
When is lean flame out likely to occur?
Low fuel pressure
Low engine speed
High airspeed
High altitude
When is rich flame out likely to occur?
Over rich mixture
Rapid engine acceleration
How many separate primary control actuation systems must there be and why?
3
In case of failure
As speed increases, what do aileron lockout devices do?
Restrict the movement of outboard ailerons, leaving inbound ailerons and spoilers to effect roll at high speed
Where do the speed signal inputs come from for the aileron lockout device?
CADC (Central Air Data Computer)
What is the aileron powered by and how many?
2 hydraulic systems
What would an aileron lockout failure at low speeds indicate?
One or both of the lockouts have failed to unlock the outboard ailerons
What are the implications if aileron lockout failure occurs during approach?
Decrease ability of low speed roll characteristics
Reduce crosswind landing capability
How many hydraulic systems power the rudder acutator?
3
What are yaw dampers for?
Reduce dutch roll
Assist in turn co-ordination
Where does the yaw damper get info for speed?
From the CADC (central air data computer) which is blended from Ring laser gyro that is part of Inertial reference unit (IRU)
What happens if one yaw damper is lost?
Flight crew need to restrict forward speed and altitude to within published yaw damper inoperative limits
How many spoiler panels are there on each wing? How many hydraulic actuators are allocated for the spoiler panels?
12 spoiler panels in total, 6 per wing (4 outter, 2 inner)
Each spoiler panel has its own hydraulic actuator
What are the spoiler panels used for in the air?
Slow aircraft in flight
Steepen descent gradient
Reduce lift
Increase drag
What are the spoiler panels used for on the ground?
Spoil any lift
What controls the spoilers?
Speed brake lever
What are the different positions of the speed brake?
Down (spoilers stay down, even after landing)
Armed (spoilers automatically deploy to full up once landing gear bogie has levelled on touch down)
Up (allows spoiler panel to be used as speed brakes in flight)
If the speedbrake lever is NOT in the armed position, but all three conditions are met and reverse thrust is applied, what happens to spoilers and speedbrake lever?
Spoilers will automatically extend and speedbrake lever will move to up position
How many elevator panels are there and how many hydraulic systems power them?
Two elevator panels
3 hydraulic systems
What is the mach trimmer?
Nose up trim application when operating around transonic speeds
Where does the mach trimmer get its speed info from?
CADC (central air data computer)
What does the flap/slat asymmetry monitoring system do?
Stops flaps being extended further should one wing high lift devices extend at different rate than the other
What does the flap load relief system do?
Prevent exceedance of flap limit speed when flaps are set to 25 by retracting flaps to previous stage.
COCKPIT FLAP LEVER WILL NOT MOVE WHEN THIS HAPPENS.
When speed is reduced to below the speed limit, the flap will automatically extend to previous settings
Which is always greater, CAS or EAS?
CAS
Can you intentionally fly above Vmo/Mmo?
No
What will flying above Mmo do?
Creation of shockwaves
Pilot will feel buffet through elevator (stalling)
What is Vdf? Is it IAS or TAS?
Max demonstrated dive flight speed
IAS
What is Vs?
Stall speed
Minimum control speed for level flight with 2 engines
What are the most adverse conditions for Vs?
Power off Forward CoG 1G Out of ground effect Max take off weight
As the speed of sound decreases, what happens to coefficient of lift?
Decreases
If you lose one engine, how much performance is lost?
80%
What power and speed is the asymmetric condition worsened>
High power
Low speed
Do aircraft with counter rotating props have a critical engine?
No
The speed of sound varies according to what?
Environment temperature
As airflow moves from supersonic to subsonic, what happens to temp, pressure, velocity, mach number, density and flow direction?
Temp rise Pressure rise Velocity drop Mach number drop Density rise Flow direction NO CHANGE
What will the difference be in Mcrit value for low thickness/chord ratio compared to high?
Low will have a higher Mcrit
The overall drag for thin wings is less that for straight wings at all speeds, true or false?
True
What is static stability?
Initial tendency for an object to return to equilibrium after a disturbance
What is positive static stability?
Tendency to return to equilibrium
What is negative static stability?
If object tends to continue in direction of distrubance
What is neutral stability?
When object is displaced from equilibrium it stays in new position
What is dynamic stability?
Resulting motion with time after disturbance
What is positive dynamic stability?
If the amplitude of motion decreases with time after disturbance
What is negative dynamic stability?
If the amplitude of motion increases with time after distrubance
What is neutral dynamic stability?
If amplitude of motion remain unchanged after initial disturbance
What happens to controllability with increased stability?
Lower the controlability
What is positive longitudinal stability?
Aircraft will return to trimmed position after being displaced in pitch
What position of centre of gravity will positive longitudinal stability occur?
When centre of gravity is ahead of centre of lift
Where would centre of gravity be if there was negative longitudinal stability?
Centre of gravity behind centre of lift
What will engines below the wing do to static longitudinal stability when power is increased?
Reduce longitudinal stability
Which axis is directional stability about?
Normal axis
What factors affect the longitudinal stability?
CoG Wing Engine nacelle and fuselage Thrust line Power
What does a large fin surface area that is displaced aft of CoG do to directional stability?
Increases it
What do aft body strakes do to directional stability at high and low speeds?
Increase directional stability at both high and low speeds and
What happens to directional stability at high airspeed and high altitude?
Direction stability is lower
What is the effect of dorsal fin extension on directional stability?
Preserves directional stability at large side slip angles
What contributes for to direction stability, swept or straight wing?
Swept
If the prop or jet inlet is ahead of the centre of gravity, what does an increase in power do to directional stability?
Decreases it
When are the destabilising affects of power most noticeable?
High power at low speed
If the nose yawed to the right what would the positive lateral stability do?
Sideslip to the right
Cause greater lift on down going (right) wing, rolling aircraft to the left
What does a large dihedral wing do to lateral stability?
Increases it
What does high velocity slipstream behind the props do to lateral stability?
Decreases it
What does deployment of flaps do to lateral stability?
Reduces effective dihedral and therefore reduces lateral stability
When does dutch roll occur?
High lateral stability and low directional stability
What happens to stability as altitude increase?
Spiral stability increases
All other stability decreases
At what height and speed is dutch roll tendency the highest?
Highest at high altitude and high speeds
What is the formula for calculating rate one turns?
(TAS / 10) + 7 = xx bank angle degrees
Does aircraft weight affect the turn radius?
No
What does the mach trimmer do?
Automatically trims nose up during transonic speed range
What is the airflow velocity, static pressure, density, total pressure and temp with normal and oblique shockwave?
Reduction in velocity to subsonic Rise in static Rise in Temp Less total pressure Rise in density
What is the airflow velocity, static pressure, total pressure and temp with expansion wave?
Increase in velocity
Increase in static pressure
increase in temp
No change in total pressure
What happens to Pressure, density and velocity in divergent ducts with sub sonic flow?
Pressure and density increase
Velocity decrease
What happens to Pressure, density and velocity in divergent ducts with supersonic flow?
Pressure and density decrease
Velocity increase
What happens to Pressure, density and velocity in convergent ducts with sub sonic flow?
Pressure and density decrease
Velocity increase
What happens to Pressure, density and velocity in convergent ducts with supersonic flow?
Pressure and density increase
Velocity increase
What happens to shockwave, COP, nose position, controls, Clift and Cdrag when passing Mcrit?
Shockwave forms COP moves aft Nose down Control buffet Clift decreases Cdrag increases
What speeds would aileron reversal occur in?
Transonic range
What is spiral stability?
Ability to recover from spiral dive after yaw input
What is spiral instability?
Tendency to enter spiral dive
What does increase spiral stability lead to?
Dutch roll
What does spiral stability increase with?
Increase in altitude
What does dutch roll tendency increase with?
Increase in altitude
What happens to lateral, longitudinal and spiral stability as altitude increases?
Lateral decreases
Longitudinal decreases
Spiral increases
Where do aileron lock out warning messages illuminate?
EICAS
When are inboard ailerons active?
ALWAYS
What are yaw dampers used for?
Used to reduce dutch roll
What is ram effect?
Air compressed (higher density -greater mass airflow) at the engine intake due to high forward velocity
What happens to ram effect as airspeed increase?
Ram effect will increase
What happens to thrust with increase in speed?
Decreases
Does ram effect recover all thrust lost with increase in speed>
No, only partial
What happens in the intake cycle for BGT?
Direct turbulent free airflow to compressor
Increase potential energy of air
What happens to static pressure and velocity (dynamic pressure in compressor)?
Increasing static pressure Decrease velocity (dynamic pressure)
What happens to pressure in combustion?
Pressure slightly decreases as temp increases
What happens in exhaust stage of BGT?
Energy converted to kinetic energy to rotate shaft connecting to compressor
Remaining energy used to thrust ac
What does EPR measure?
Thrust indicating system, to adjust thrust output of engine
What shape is the intake duct?
Divergent
What is intake duct divergent?
Decreases airflow velocity
Increases static pressure
What is the primary purpose of the compressor?
To increase total pressure
When is compressor surge likely?
92-98% RPM Thrust levers opened too quickly AoA of intake too high Turbulence Altitude Heavy rain or hail Reverse thrust Side slipping Compressor blades damaged
How can you prevent compressor stall?
Variable inlet guide vanes
Variable stator vanes
Bleed valves
Multi spool compressors
What do bleed valves do?
Compressed air tapped from compressor to increase air flow over rotor blades maintaining optimum angle of attack
When is fuel added in BGT?
Combustion cycle
What is the entrance to the combustion cycle?
Divergent
How much % of air goes through snout and flare?
20% (12 to snout for swirl and 8 to flare to mix fuel and air)
How much % of air is not directed to snout?
80%
Of the air not directed to snout, what % goes to later part of primary combustion zone?
20% of 80%
What % of air the dilution zone?
20% of 80%
What % of air not directed to snout is for cooling?
40%
Where is the hottest section of combustion chamber?
1st 1/3rd (primary zone)
What are the main causes of flameout?
Turbulent weather (turbulent inlet air)
High altitude
Slow acceleration during manoeuvres
High speed manoeuvres
What is lean flame out?
Low engine speed and low fuel pressure. Generally low powered descent
What is rich flame out?
High powered climb where over rich mixture increase pressure in combustion chamber
What are the advantages of the annular chamber?
Weight and space saver
Better combustion propagation
Reduced pressure reductions
What are the disadvantages of the annular chamber?
Entire system has to be removed for maintainance
What are the advantages of the multiple chamber?
Simple to construct and maintain
What are the disadvantages of the multiple chamber?
Takes up a lot of space
Uneven delivery of air loads to turbine
What is the primary function of turbines?
Transform heat into kinetic energy
What do nozzle guide vanes do? (NGV)
Direct flow onto moving turbine blades in correct direction
What do nozzle guide vanes do to pressure and velocity?
Decrease pressure
Increase velocity
What is fitted to nozzle guide vanes to avoid tip leakage?
Shrouds
What are shrouds and where are they located?
Caps on tips of turbine blades to reduce leakage, vibration and increase strength
What is blade creep?
Length of the blade increases due to centrifugal forces acting on blade and the temp at which it operates
What are the different blade creep types?
Primary, secondary and tertiary
What is primary creep?
Process of manufacture
Considerable change in materials shape
What is secondary creep?
Occurs over lift of blade
What is tertiary creep?
Deterioration of blade rapidly until failure. Shouldn’t be fitted to engine
What is primary function of exhaust?
Develop thrust
Discharge gas to atmosphere
What direction is exhaust duct?
Convergent
What are exhaust struts??
Straighten out airflow from exhaust
How do high bypass engines reduce noise?
Mixing of coo and hot air prior to exhaust
How do blocker doors assist with reverse thrust? Are they internal or external?
Divert coldstream airflow
Internal
How do clampshell doors assist with reverse thrust? Are they internal or external?
Change direction of all air
External
Pneumatically operated
Can reverse thrust be used in the air?
No
Why don’t we use thrust reverse at low speed?
Less effective and prone to foreign object damage
What frequency noise travels great distances and creates large noise foot print?
Low frequency
What do negative torque systems do?
Sense negative torque (when prop begins to rotate faster than reduction gear and drives the engine)
What does negative torque system do to blade angle
Coarsens blade angle to reduce stress
How long does negative torque system alter the blade angle?
Coarsens blade until negative torque no longer sensed or until full coarse stop
What happens to NTS when reaches full coarse stop?
Disengage reduction gear from engine and then reconnect automatically once negative torque no longer sensed
What is the prop brake used for?
Prevent prop windmilling in flight when feathered
Holds blade during shutdown (engine still be running while blade is stationary)
What is TSS and what does it do?
Thrust sensitive signal or autofeather
Automatically feathers prop if required after takeoff
When does TSS work?
System must be armed prior to take off.
Once prop develops more than 500lbs of thrust, system will feather prop if output drops below this mark
What is primary purpose of APU?
Provide bleed air for pneumatics
aircon, engine start without GPU, anti ice
Where is APU located?
In the tail
What are some conditions that lead to APU automatic shutdown?
Low oil pressure High oil temp High EGT Over speed Duct overheat
Where in engine is fire detection located?
Engine cowl
How many fire extinguishing bottles are installed in the engine nacelle
Two
What is the basic sequence for undercarriage retraction?
Sequence valve ensure doors open first Undercarriage downlocks removed Indicators go from green to red Wheels come up Uplocks come in Doors close and lock Transit light goes out
What is the ground lock?
Prevents inadvertent retraction of gear on ground
How does the gear lock work?
Safety switch is opened in gear circuit if aircraft is on ground and allows spring loaded pin in solenoid to block gear selector movement
In the 767, how are uplocks operated?
Electrically operated solenoids
What is the most common tyre tread and why?
Ribbed tyre
Offers low rolling resistance, good directional stability and water displacement
What are advantages of tubeless tyres over tubed tyres?
Lighter
Less chance of puncture
Cooler (less friction)
Fusible plugs (protects from blowing out)
What is the power source for the brake system?
Hydraulic system pressure of 3000psi
What does Brake control valve do?
(BCV)
Reduces hydraulic pressure to operating range (1500psi)
Regulates flow of return fluid
Which system does anti skid system work in conjunction with?
Auto brake system
What does anti skid provide?
Touch down protection
Skid protection
Locked wheel protection
Hydroplane protection
If a skidding wheel is detected, what happens to pressure on the brake for that wheel?
Pressure is reduced (NOT REMOVED)
What is the formula for hydro plane speed for static wheel
7.7 square root (Tyre pressure psi)
What is the formula for hydro plane speed for rotating wheel?
9 square root (tyre pressure psi)
Which tyres are more prone to hydroplaning?
Forward tyres
What will cause auto brakes of 767 to disarm?
Pilot hits brakes hard enough (>750psi) Retraction of speed brake lever to down Selector switch to disarm or off Advancing throttle INS u/s Anti skid u/s
What are the degrees of steering for rudder pedals and tiller wheel?
Rudder +/- 7 degrees
Tiller +/-65 degrees
Can different hydraulic fluids be mixed?
NO
What does the hydraulic reservoir do?
Allows for variations in fluid level Provides reserve for leaks Provides space for returning fluid Allows for changing temp and volume Provides positive pressure to pumps to avoid cavitation
What pressure does hydraulic pump provide up to?
3000psi
What is EDP and what does it do?
Engine driven pump
Primary source of pressure for hydraulic system
How does EDP provide pressure for hydraulic system?
Constant or variable displacement pumps
What do hydraulic pressure relief values do?
Ensure pressure in system isn’t exceeded
How do hydraulic pressure relief valuves work?
Spring loaded valve being forced by high pressure fluid which allows excess to pass back into a return line to reservoir.
What do check valves do?
Allows fluid to flow in one direction only
Where are check valves located?
Downstream of the pump
What are shuttle valves?
Enable services to be provided with hydraulic pressure from one of two sources. Whichever line has greater pressure allows that line to provide fluid
What are selector valves and how are they operated?
Controlling valve which opens to allow high pressure oil into actuating hydraulic actuator.
Electrically operated
In the 767, what hydraulic systems are there?
Left, centre right
What power sources are used by LEFT hydraulic system?
EDP (engine driven pump)
ACMP (alternating current motor pump)
What power sources are used by CENTRE hydraulic system?
2ACMP (alternating current motor pump)
ADP (air driven pump)
RAT (ram air turbine-emergency)
What power sources are used by RIGHT hydraulic system?
EDP (engine driven pump)
ACMP (alternating current motor pump)
What is RAT?
Ram air turbine
What does RAT do?
Provides emergency hydraulic power using ram air
How can RAT be deployer?
Automatically or manually
When can RAT be retracted?
Only on ground
Where is hydraulic pressure displayed?
Centre of EICAS panel
What are advantages of pneumatics?
Lighter Cheaper Low fire risk Once used, air can be dumped over board Easily compressed
What are disadvantages of pneumatics?
Air must be dried
Components must have separate lubrication system
More prone to leaks
What are the advantages of hydraulics system?
Uses incompressible hydraulic fluid Self lubricating Fewer problems with water or water contamination Easy to find leaks Faster response times
What are the disadvantages of hydraulic systems?
High fire risk
Requires coolers
Hydraulic oil can destroy electrical insulation surfaces, finishes and seals
Hydraulic oils cant be mixed
In 767, how do we control leading edge slats and double slotted fowler flaps?
Flap lever which sends signal to three power drive units (PDU)
What happens to the flap and flap lever if airspeed exceeds set limitation?
Flaps automatically retract
FLAP LEVER DOES NOT MOVE
What type of pressure is kept in the cabin compared to outside?
Higher pressure
Should the pressure in the cabin be less than the atmospheric pressure?
No
Where is the outflow valve located and why?
Rear of cabin to draw pollutants away from the flight crew
What are the three functions of the outflow valve?
Isobaric control (maintaining cabin altitude)
Differential pressure protection (ensuring max pressure not exceeded)
Negative pressure differential (prevents negative pressure being exceeded)
What pressure is maintained by the pressure controller sensors during climbs and descent?
500fpm for climb
300fpm for descent
What do safety valves do?
Provide positive and negative over pressure protection
Automatically dump remaining cabin pressure on landing
Allow emergency dump during rapid decompression
Where is the negative pressure relief valve located?
Cargo doors
When will negative pressure relief valve open?
Any time when outside pressure exceeds cabin pressure
What is the source of pressurisation?
Engine or APU bleed air and atmospheric air mix
What must pilot enter in the system for automatic pressurisation of system?
Destination elevation
When will pressurisation system warnings be displayed on EICAS?
If cabin altitude exceeds 10000
O2 masks drop if cabin altitude exceeds 14000
What systems typically use electrical anti ice?
Pitot static probes Angle of attack vanes Total air temp probes Engine probes Mach probes Windscreens Inner sections of prop Engine intakes
Can rain repellent be used on a dry windscreen?
No
What will the use of thermal protection do to engine performance? When is it most noticeable?
Reduce engine performance as air sourced from output of engine (engine bleed air).
During high power settings at take off and climb
How are the de-icing boots used?
Pneumatically
What are the de-icing boots?
Slightly raises black areas on leading edge of wings, comprised of rubber material that inflate cracking any ice
What fuel is typically used in Australia for jets?
JETA1
What type of additives can be found in turbine fuel?
Anti static (required if refuelling with pax on board) Anti oxidants Anti fungal Anti freeze Lubricating additive
What could be an indicator of icing detected in the fuel system? And what should be done to rectify?
Low filter pressure.
Pilot select bypass generally for short periods (1min)
What is incorporated in the fuel tank to prevent CoG changes when turning?
Baffles
What is the purpose of the LP pump?
To provide uninterrupted flow of fuel to high pressure pumps
How many booster pumps are used during takeoff? Landing? Cruise? Descent?
Take off 2
Landing 2
Cruise 1
Descent 1
What does HP pump do?
Supplies pressure to fuel manifold
What is the most common HP pump type?
Variable displacement
Where does FCU (fuel control unit) receive its inputs from?
Altitude
Throttle position
Inlet air temp
Speed of N2
What is the function of the circuit breakers?
Provide circuit protection and isolation from excessive amps
What power do batteries supply?
Power for start and emergency power
What does IRS use?
3 gyros and 3 accelerometers
Outside of what latitudes will RDMII display true heading? In this case what happens to VOR flag?
73N 60S
VOR flag inoperative
Where is input for RDMI from?
IRS (inertia reference system)
Where do inputs for VSI come from?
ADC and IRS
What level do radar altimeters operate?
0-2500 ft AGL
The FMS systems managers which flight path?
LNAV and VNAV (lateral and vertical flight paths)
How should entries be made in the CDU?
One CDU used to enter data, one used to cross check
What do the boxes represent on CDU?
Must have info
What do the dashes represent on CDU?
Requested info
What is done on the IDENT page?
Preflight, first page to have data entered.
Which page allows present position of plane to be supplied to IRS and can consist of LAST POS, REF AIRPORT or GATE?
Position initialisation page
What is the RTE page?
Route page.
Enables crew to enter route into FMC
How would pilots display possible departure routes?
Go to SID entry and then select DEP/APR button
Where would gross weight, ZFW, fuel reserves, cost index and cruise altitude be entered?
Performance initialisation page
Where would the crew enter the V1, VR and V2 speeds?
Take off reference page
Where can the crew monitor the flight plan of the aircraft through the CDU? What else can be monitored on this page?
Progress page.
Last waypoint, next waypoint, destination, speed, TOPD, wind
What does the Electronic flight instrumentation system (EFIS) consist of?
EADI EHSI Symbol generator Control pannel FMS
The captains RDMI and VSI are supplied by what ?
RDMI by R - IRS
VSI by L - IRS
The first officers RDMI and VSI are supplied by what ?
RDMI by L - IRS
VSI by R - IRS
What display modes are the on the EDSI?
MAP, PLAN, ILS and VOR
What are the different colour indications for MAP mode?
Green = engaged flight mode White = present status situation Cyan = non active and background info Red = warning Amber = cautionary info Black = blank areas OFF condition
What does expanded VOR mode show?
VOR nav info
Weather radar
TCAS available
What does expanded ILS mode show?
ILS info
Weather radar
TCAS available
What does PLAN mode show?
Static true north orientated map of flight planned route.
No weather radar
Which of the modes use track? Which use heading?
MAP and PLAN use track
VOR and ILS use HDG
Is the flight director manual or automatic?
Can be both
Will manual position of lever disengage autothrottle?
No
How many autopilots are required for Approach mode?
2
Which modes will autopilot are with approach mode?
Glide Slope and LOC
How many autopilots does 767 use?
3
How many autopilots does AFDS require?
1
When can you use more than one autopilot?
During precision approach
How many autopilots are required for autoland?
2
What does fail operational mean?
Means system has adequate redundancy to allow approach to continue if one of three autopilots fails
What does fail passive mean?
If a fault is detected in one of the autopilots.
Landing is being done with 2 autopilots
A/C unable to conduct auto landing in extreme low visibility
What happens as altitude decrease to 1500 ft during landing?
LOC and GS have been capture and APP modes will be armed
When is FLARE mode active?
45 ft
When is ROLLOUT mode activated?
5 ft
At what height does pilot assume command of rudder?
1500 feet
What happens at 500 feet during landing?
Runway align submode becomes active. (reduces crab with cross wind)
Between what heights will aircraft automatically introduce increment of nose up trim in preparation for flare?
330-100ft
What happens at 15ft during landing?
SPD mode on auto throttle becomes IDLE
How long will rollout mode continue?
Until aircraft comes to fullstop OR autopilots are disengaged
What are the three types of message displayed on EICAS?
Warning (red)
Caution (yellow)
Advisory (yellow)
What does the CANCEL switch do?
Removes displayed cautions and advisories (warnings not affected)
Shows next page of messages
What does RECALL switch do?
Recalls cancelled cautions and advisories
Goes to page 1 of messages
Which direction does GPWS mode operate in?
Vertically only
What are the soft warnings for mode 1 excessive descent rate?
Aural: Sink rate sink rate
Visual: GND prox light
What are the hard warnings for mode 1 excessive descent rate?
Aural: Whoop whoop pull up
Visual: Pull up light
What are the soft warnings for mode 2 excessive terrain closure rate?
Aural: Terrain, terrain
VisualL GND Prox light
What are the hard warnings for mode 2 excessive terrain closure rate?
Aural: Whoop whoop, pull up
Visual: Pull up light
What does extension of flaps do if the hard warning for mode two is being heard?
Replaced with terrain terrain
What are the soft warnings for mode 3 altitude loss after take off/go around?
Aural: Don’t sink
Visual: GND prox light
What are the hard warnings for mode 3 altitude loss after take off/go around?
Aural: Too low terrain
What are the soft warnings and when do they occur for Mode 4 unsafe terrain clearance in config?
Below 190 kts at 500ft
Aural Too low gear
Visual: GND prox light
What are the hard warnings and when do they occur for mode 4 unsafe terrain clearance in config?
Above 190 kts below 1000
Aural: Too low terrain
What does the TCAS rely on?
Interrogation of other a/c SSR transponder
Does TCAS use ground SSR?
No, totally independent of any ground based SSR
How long after TCAS messages does pilot have before impact?
20-35s
What colour are TA and how long do you have?
Amber circle
20-48 s
What colour are RA and how long do you have?
Red square
less than 25s
What is proximate traffic?
Cyan diamond, is neither TA or RA but within 6nm and has 1200ft separation
What is other traffic for TCAS?
Hollow cyan diamond.
Above and separated by more than 2700ft
What does +## symbol mean in TCAS?
Indicated traffic is above you (i.e +05 is 500 ft above)
What does - signal mean in TCAS?
Indicated traffic is below you
What does up arrow indicate in TCAS?
Traffic is climbing
What does down arrow indicate in TCAS?
Traffic is descending
What does TA 6.8-1.1 Up arrow mean?
No bearing info. Intrudering aircraft is 6.8 nm away 1100 ft below and climbing
What conditions will cause TCAS to fail?
Mode S transponder fail
Barometric altitude sources fails (TCAS OFF)
Radio altimeter fails
What time do you have to action preventative TCAS advice? What about Corrective?
5s for preventative
2.5 for corrective
What warnings override the TCAS?
GPWS and Stall
How many parameters and for how long does DFDR record?
300 parameters
25 hours
Where is the DFDR located?
Tail
