AFT aero and systems notes Flashcards
1
Q
What are the 4 types of reaction engines?
A
Rocket
Ram Jet
Pulse Jet
Gas Turbine
2
Q
What is a rocket?
A
Self contained air and fuel in pressurised container
3
Q
What is a ram jet? What entry and exhaust duct type does it have?
A
No moving parts, requires large forward speed to operate
Divergent entry duct
Convergent exhaust duct
4
Q
What is a pulse jet?
A
Similar to Ram jet but on intermittent cycle
5
Q
What is a gas turbine?
A
Turbine driven compressor. Does not require forward airspeed to compress the air entering the engine
6
Q
What is maximum thrust of a gas turbine limited by?
A
The maximum turbine temperature
7
Q
If there was a large increase in gas temperature from the air intake to the turbine, what happens to the volume of gas, acceleration of the air and thrust produced?
A
Volume of gas increases
Acceleration of air increases
Thrust produced increases
8
Q
What happens to thrust as air temperature increases?
A
Thrust decreases
9
Q
What happens to thrust as altitude increases?
A
Thrust decreases due to less dense air
10
Q
What happens to thrust if the mass air flow decreases?
A
Thrust decreases
11
Q
What is the thrust formula?
A
Thrust = (Mass airflow X Jet exhaust velocity) - Aircraft forward speed
12
Q
Describe a basic pure turbo jet.
A
One or more compressors driven by set of turbine wheels.
13
Q
What is a spool?
A
Compressor at the front of an engine and its accompanying set of turbine wheels at the rear
14
Q
How does a pure turbo jet deliver its thrust?
A
Reaction to the rearwards acceleration of exhaust gases after it has passed through the turbine sections of the engine
15
Q
What happens to the static pressure at the exhaust outlet of pure turbo jet compared to the intake?
A
Roughly double
16
Q
What is the EPR?
A
Engine pressure ratio.
Static pressure at the exhaust outlet compared to that at the intake
17
Q
What indication does the EPR give to pilots?
A
Thrust output
18
Q
What would a blocked EPR cause to the gauge?
A
Cause it to overread
19
Q
Describe the basic high by-pass jet (turbo fan)
A
Not all air passes through the engine core and combustion chamber. Large fan (N1) is at the front of the compressor and driven by extra turbine at rear of engine
20
Q
What is the by-pass ratio?
A
Ratio of air which bypasses the engine core compared to the air which passes through the core
21
Q
What is the formula for the by-pass ratio?
A
By-pass ratio = (By-pass mass flow) / (Engine core mass flow)
22
Q
What would an engine sound like, efficiency be with a high by-pass ratio?
A
Quieter and more efficient
23
Q
Where is the majority of thrust produced in a high by-pass ratio engine?
A
From the by-pass fan air
24
Q
Where is the majority of thrust produced in a low by-pass ratio engine?
A
From the jet exhaust
25
What are the advantages of the free power turbine turbo prop?
Lower starting torque (since starter doesn't drive the prop)
Variable prop speed
High torque at low speed
26
What is the main difference between gas turbine and piston cycle?
Gas turbine is continuous
27
What is the role of convergent ducts?
Increase velocity
Decrease pressure
Decrease temperature
28
What is the role of divergent ducts?
Decrease velocity
Increase pressure
Increase temperature
29
In the compressor, what happens in the centrifugal flow?
Impeller accelerates mass air flow and imparts a pressure rise and a diffuser (divergent duct) to increase pressure
30
What does an axial flow compressor consist of?
Rotor blades attached to main rotor assembly
| Stator vanes between each rotor blade (do not rotate)
31
What is the role of the rotor blades and stator vanes in axial flow compressor?
Rotor blades increase velocity of airflow
| Stator vanes are located between each rotor blade, do not rotate. They increase pressure by forming divergent duct
32
How are rotor blades shaped in axial flow compressor?
Aerofoil shaped and therefore must be presented at correct angle of attack
33
How are stator vanes shaped in axial flow compressor?
Shaped to direct air from one set of rotors to the next at correct angle of attack
34
Where is the largest air load in the axial flow compressor?
Rear most blades of compressor
35
Compared to a centrifugal compressor of the same frontal size, what does an axial flow compress do to air and pressure?
Consumes more air and gives bigger pressure rise
36
What types of airflow control are there?
Variable inlet guide vanes (VIGV)
Variable stator vanes
Bleed air valve (surge valve)
37
What are variable inlet guide vanes? Where are they located?
Change angle at which relative airflow meets the first stage compressor, preventing surge and stall.
Located at front of compressor
38
What are variable stator vanes?
Change angle of each row of stator vanes to maintain correct angle of attack when engine operating 'off design RPM'
39
What are bleed air valve (surge valve)? Where is it used? What sort of compressor is it used in?
Used with axial flow compressors, valve towards rear of compressor.
Valve opens when operating off design RPM to reduce compressor outlet pressure and increase mass airflow across early stages of compressor
40
What percentage of total mass airflow enters the combustion chamber through the primary zone? What is it for?
20%
| Flame stabilisation and combustion
41
What percentage of air enters the primary zone through holes in the wall of the flame tube?
20%
42
How much of the total mass airflow is used for cooling and dilution further down the chamber?
60%
43
What percentage of air is used for combustion? What is it called?
12%
| Primary air
44
Where does primary air enter the combustion chamber?
Through the swirl vanes at the front of the combustion chamber
45
What is the purpose of the swirl vane?
Reduce axial flow
| Keep flame stable in the primary zone of combustion
46
Where does the highest gas temperature occur during combustion?
In the primary zone of combustion
47
When is a rich flameout possible?
Mixture is too rich
| low speed and high powered climb
48
When is a lean/weak flameout possible?
Mixture is too weak
| High speed and low power descent
49
With a multiple combustion chamber, how is pressure equalised? What else does this device allow?
With interconnectors.
| Allows flame propagation between chambers
50
What is the most effective combustion chamber in terms of efficiency, cost and weight?
Annular
51
What are NGV?
Nozzle guide vanes.
Positioned in front of each turbine wheel.
Stationary aerofoil blade shaped as convergent ducts
52
What is the purpose of the NGV?
To increase velocity of gas stream onto next set of turbine blades at correct angle of attack
53
What are turbine blades and what are their purpose?
Blades attached to turbine disc.
| Extract energy from gas stream to drive compressor, fan or gearbox
54
What are shrouds?
Caps on the tips of some blades to reduce gas leakage, reduce vibration and increase strength
55
What is blade creep? What causes it?
Increasing in length of turbine blades
| Caused by excessive exposure to high temps, centrifugal forces and stress
56
What are the different types of blade creep and when do they occur?
```
Primary creep (during manufacture)
Secondary creep (during service life)
Teriary creep (failure)
```
57
What is the most critical temperature in the engine?
Turbine temperature
58
In a turbo jet engine, how much energy of the total energy of the gas stream is used to drive compressor?
75%
59
In a turbo jet engine, how much energy is used for thrust?
25%
60
What are support struts?
Used to keep exhaust flow streamlined
61
What does the jet pipe do?
Carries exhaust gases from turbine to propelling nozzle
62
What is the propelling nozzle?
Convergent to Increases the velocity of exhaust to give final increase in thrust
63
What is the main source of noise from a turbo jet?
Exhaust noise
64
What is the main method of noise suppression for turbo jets?
```
Increase frequency (Hz) of exhaust noise from low to high.
Done by mixing cool air with hot exhaust gases
```
65
Which is quieter, turbo prop or turbo fan?
Turbo fan
66
What is the main source of noise from a turbo fan?
The fan and the turbine
67
What is thrust reversal?
Angling the thrust to go forwards
68
What does thrust reversal do to landing distance?
Decreases landing distance
69
When should thrust reversers be used?
Early stages of landing roll when speed is high.
70
Why should we not used thrust reverse at low speeds?
Hot turbulent air can enter the engine along with foreign objects
71
What reverse thrust is used on turbofans?
Cold by-pass only (coldstream reversers such as blocker doors)
72
How do blocker doors work?
Blocker doors in the by pass duct to redirect coldstream air out through cascade vanes in the engine cowl
73
What are interlocks?
Prevent thrust lever from being moved to reverse position unless engine is running at low power setting
74
What are turbine oils like?
Medium to low viscosity
| Stable under high operating temperatures
75
What two things act together to maintain a constant RPM in a turbo prop?
Fuel control unit
| Propeller governor
76
What happens in turbo prop as power levers are advanced?
FCU sends extra fuel to combustion chamber which increases engine output and tries to drive turbine faster.
Prop governor detects this and coarsens blades to absorb extra energy and provide more thrust at constant RPM
77
What is the beta range?
In a turbo prop, the ground handling range, where the prop blade angle isn't controlled by the prop governor but via the power lever position via oil pressure control system
78
What is the NTS?
Negative torque system.
| Provides a signal which increases prop blade angle to limit negative shaft torque
79
What conditions is NTS likely to operate?
Temporary fuel interruptions
Air gusts loads on prop
Normal descents with lean fuel scheduling
High Compressor air bleed conditions at low power
Normal shutdowns
80
What is TSS?
Thrust sensitive system (autofeather)
81
What does TSS do?
Automatically feathers prop if there is a power loss during take-off.
Automatically increases blade angle and causes prop to feather
82
What is the safety coupling?
Safety feature of the turbo prop.
Disengages the reduction gear from engine if it's operating about a preset negative torque value. (much higher value then required for NTS)
83
After being disengaged, when will the reduction gear be re-engaged?
Automatically during feather or engine shutdown
84
What is a prop brake?
Rapidly slow prop after engine shut down.
| Prevents windmilling on ground
85
In a turbojet fuel system, what happens to fuel flow as altitude increases?
Fuel flow decreases
86
What are impellers used for in the fuel system?
Boost pumps in tanks to supply high pressure
87
What problems could there be if using AVGAS instead of kerosene in a jet engine?
Decrease range
Poor altitude performance
Over temperature
Over speed
88
What is the specific gravity and flash point of AVTUR compared to AVGAS?
AVTUR SG = 0.8, flash point = 46 degrees
| AVGAS SG = 0.72, flashpoint = -40 degrees
89
How is fuel measured?
Capacitance type system with probes (capacitors) in fuel system
90
What is a standpipe?
Prevents accidental dumping of entire fuel load if the dumps not shut off manually at desired quantity
91
What are baffles?
Dividing partitions in fuel tank used to limit movement of fuel
92
Hot bleed air from the compressor, hot oil or electrical system is used to prevent ice on what devices?
Wing leading edge and props on turbo props
93
What negative effect does hot air anti ice have?
Decrease in thrust when air is taken from compressor
94
What is the normal procedure for starting the turbine engine?
Starter and ignition on
When N2 = approx 10/15% add fuel and watch for light off
Check for rapid TOT increase to confirm light off
95
What speed is self sustaining?
35-50%
96
When can a hot start occur?
High fuel flow
Low RPM
Tailwind
97
What are the indicators of a hot start?
After light off, TOT increases beyond maximum
98
What are the indicators of a wet start
Added fuel at 15% but no light up occurs
99
What is a hung start?
Not enough starter power to reach self sustaining speed
100
What may a hung start lead to?
A hot start
101
What should be done in the event of a hot, wet or hung start?
Shut fuel off
| Keep starter on
102
What is the formula for specific fuel consumption?
Fuel flow / thrust produced
103
Is a high or low specific fuel consumption (SFC) preferred?
Low
104
What will cause an increase in specific fuel consumption?
Increase in ambient temperature
Decrease in compressor pressure
Operation outside design RPM
105
What are the advantages of turboprop?
Higher thrust at low forward speeds
Lower thrust specific fuel consumption
Quieter than turbofan or pure jet
More suited to short sectors
106
What are the disadvantages of turboprops?
Engines are heavier
Not suited to high altitude
Not suited to long sectors
107
What is the APU used for?
Provide source of electrical and pneumatic power independent of ground support or aircraft engines
108
In the event of an engine failure, what can be done to assist with electrical load?
Turn on the APU
109
What happens to engine bleed air that is not required by the aircraft of APU?
Dumped overboard downstream of turbine section
110
What will activate the APU automatic shutdown?
```
Fire detection
Automatically activated fire extinguisher
Low oil pressure
High oil temp
High exhaust gas temp
Overspeed
Duct overheat
```
111
What happens in a convergent duct if the flow is supersonic?
Velocity decreases
Pressure rises
Density rises
112
What happens in divergent duct if the flow is supersonic?
Velocity increases
Pressure decreases
Density decreases
113
What is subsonic flow?
Flow velocity less than speed of sound
114
What is sonic flow?
Flow velocity at speed of sound
115
What is supersonic?
Flow velocity greater than speed of sound
116
What is Mfs?
Mach Free Stream
| Mach number of aircraft through the air
117
What is the local mach number?
Mach number of the flow at a particular location on an aircraft/aerofoil
118
What is Mcrit?
Critical mach number.
Mach number which first produces evidence of local sonic flow.
Start of transonic range
119
Above what speed does shockwaves form on the wing?
Mcrit
120
What is Mcdr?
Critical drag rise mach number.
| Significant shockwave related problems as shockwave grows and moves rear
121
What is higher, Mcrit or Mcdr?
Mcdr
122
What is Mdet?
Detachment mach number.
| Aircraft mach number at which bow waves attaches to leading edge or nose.
123
What speed range does Mdet mark? And what is the flow type?
Marks end of transonic speed range
| All flow is supersonic above Mdet
124
What is Mmo?
Maximum operating mach number.
| Highest mach number at which aircraft can be intentionally flown
125
What happens if you fly above Mmo?
Shock wave formation
Control problems
High airframe stresses
126
What happens to velocity, mach number, static pressure, density, temp and total pressure in a normal shockwave?
Decrease in velocity and mach number (subsonic)
Increase in static pressure, density and temperature
Less total pressure
127
Where are oblique shockwaves likely to form?
Around compressive corners in supersonic flow
128
What happens to airflow in oblique shockwave?
Change in direction
Reduction in velocity and mach number
Rise in density and static pressure
129
What happens to static pressure, velocity and temp in expansion waves?
Decrease in static pressure and temp
| Increase in velocity
130
What is the speed range for subsonic?
0-0.75M
131
What is the speed range for transonic?
0.75 - 1.20M
132
What is the speed range for supersonic?
1.2-5-0M
133
What is the pitching tendency as shockwave forms?
Pitch down
134
What is mach tuck?
CP moving rearwards generating a nose pitch down
135
What does the Mach trimmer do?
Automatically applies back elevator trim to compensate mach tuck as speed increases
136
What are the advantages of swept back wings?
Delays compressibility effects
Increase Mcrit and Mcdr
Increase force divergent number
Reduced CL changes with both speed and AoA
Improved lateral and directional stability
137
What are the disadvantages of swept back wings?
Tendency to stall tip first
Reduced max CL and higher stall angle
Reduced trailing edge device effectiveness
Dutch roll tendency
Structural complexity
High induced drag at high angle of attack
138
What is super-critical wing section?
Flattened top surface to reduce top surface acceleration and delay compressibility effects
139
What does super-critical wing section do?
Helps lift at low speed and high angle of attack
140
What happens to lift, drag, pitch and centre of pressure as aircraft passes Mcrit?
Increase in drag
Decrease in lift
Pitch down
CP move rearwards
141
What do vortex generators do?
Delay shock induced separation by reenergising boundary layer.
142
What can be done to assist with dutch roll tendency?
Yaw dampers
143
What do yaw dampers do?
Automatically applying a cancelling rudder input when yaw is sensed
144
What are the two types of yaw dampers?
Series and parallel
145
What does the parallel type yaw damper do? When can it be switched on/off?
Moves rudder pedals
| Must be off for take off/landing
146
What does the series type yaw damper do? When can it be on/off?
Does not move rudder pedals
| Can be on at all stages of flight
147
What provides the signals to the yaw damper?
Rate gyro
148
What does a swept wing do to stall angle of attack, maximum CL and drag?
Increases stall angle of attack
Reduces max CL
Increases drag
149
What is the lift and drag like of a swept wing compared to a straight wing?
Less lift more drag
150
As a swept wing approaches the stall, what happens to centre of pressure?
CP moves forwards and inwards
151
In a swept wing plane, what is tendency of pitch at stall?
Pitch up
152
What does increased gross weight do to stall speed?
Increases the stall speed
153
What do use of flaps do to stall speed and CL?
Decrease stall speed
| Increase max CL
154
What does a forward CoG do to stall speed?
Increases stall speed
155
At higher altitude, what is the stall speed IAS and EAS?
IAS and EAS stall speed increases.
| IAS greater than EAS
156
What is Va?
Manoeuvring speed
157
What happens if full control deflection occurs below Va?
G stall before load limit is reached
158
What happens if full control deflection occurs above Va?
Load limits being exceeded before stall occurs
159
What is the Va for a heavier aircraft compared to a lighter one?
Faster for heavier gross weight
160
In equilibrium what do all the forces equal?
```
Weight = lift
drag = thrust
```
161
Where does lift act through?
Centre of pressure
162
What is the lift formula?
```
CL x 1/2 x p Vsquared x S
Wherer CL = Coefficient of lift
p = air density
V= velocity or TAS of air flowing around wing
S = Surface area of the wing
```
163
What is the formula for power?
Thrust x TAS
164
What is Vimd?
The speed where total drag is minimum
| Indicated minimum drag
165
What is Vimd also known as?
```
Minimum drag speed
Best lift/drag ratio
Minimum fuel flow
Best endurance
Maximum excess thrust
Max angle of climb
```
166
Where does max still air range occur?
1.32 Vimd
167
In a headwind, what do you need to do to achieve max range?
Fly faster then 1.32 Vimd
168
What speed do you need to fly at for max endurance?
Minimum fuel flow
| Vimd
169
What speed are you said to be flying at if you are in the region of reverse command?
Less that Vimd
170
In a steady climb, what is thrust, drag, lift and weight?
Thrust > Drag
| Weight > Lift
171
Climbing using maximum excess thrust would be climbing at what?
Max angle of climb (Vx)
| Vimd
172
Climbing using max excess power would be climbing at what?
Max rate of climb (Vy)
173
What happens when flaps are extended?
Increase in lift
Increase in drag
Lower Vimd compared to clean
174
What is the TAS and IAS for max rate of climb at a higher altitude compared to lower altitude?
```
TAS = Higher
IAS = slightly lower
```
175
What happens to the minimum control speed as altitude increases?
Decreases
176
What does a forward CoG do to minimum control speed?
Lowers it
177
What does flap extension do to minimum control speed?
Increases it
178
What does gear extension do to minimum control speed?
Increases it
179
What does ground effect do to minimum control speed?
Decreases it
180
What is V1 speed?
Decision speed (whether to take off or not)
181
What are the two considerations for V1?
1. ) If take off continued, after an engine failure, at or above V1 will be possible to obtain 35 feet within schedules take off distance.
2. ) If take off rejected at or below V1, it will be possible to stop within scheduled acceleration stop distance
182
What is Vr?
Rotation speed
183
What are the two conditions for Vr?
Must not be less than V1
| Must not be less than 1.05 Vmca
184
What is V2?
Take off safety speed
185
What are the two conditions for V2?
Must not be less than 1.1 Vmca
| Must not be less than 1.2 Vs
186
In flight and after engine start, how is electric power supplied?
By 3 phase alternating current (AC) generators
187
What is an APU?
Small gas turbine located in the tail to assist with power on ground
188
What does the APU do?
Drives AC electrical generator
Provides bleed air to aircraft pneumatic system for aircon and main engine start independent of ground support or engines.
189
What does APU in flight?
Provides AC electrical power at all altitudes
| Bleed air at lower altitudes
190
What is a RAT?
Ram Air Turbine
191
What does RAT do?
Ram Air turbine.
Deployed to windmill airstream to drive generator in emergency
Drive hydraulic pump
192
What does the battery provide for the APU?
DC power for APU start plus limited emergency DC power for vital systems in complete electric failure
193
What is electric power used for? What about pneumatic?
Electrical: ground servicing, preflight and transit checks
Pneumatic: Air con and engine start
194
Does the APU need a constant speed drive?
No as it operates at constant speed
195
What happens to bleed air not required by aircraft of APU?
Dumped overboard downstream of turbine
196
Where does fuel for the APU come from?
One of the main tanks and delivered under pressure by one of the two pumps
197
When does the fuel valve open and close for the APU?
Opens when APU start is initiated
| Closes automatically on shutdown
198
Why is AC preferred to DC?
Weight and space saving and low current transmission
| AC generators are lighter than DC ones
199
What must a generator have to generate current?
Field excitation
200
What is a voltage regulator?
Controls the current supplied to windings as DC
201
What is a series wound?
Generator field is in series to armature
| As load increases voltage increases
202
What is a shunt wound?
generator field is in parallel to armature
| As load increases, voltage decreases
203
What is compound wound?
Generator that makes use of both Shunt and series winding to produce constant voltage over range of loads
204
What is the PMG?
Permanent magnet generator.
| Small generator within main generator
205
What does PMG do?
Provides initial excitation for magnetic field
206
How is PMG monitored and what is it used for?
On a voltmeter
| Check serviceability of main generator
207
When would the FIELD OFF light illuminate?
If field circuit is manually or automatically tripped, disconnecting voltage regulator from excitation field
208
What does frequency output of AC generator depend on?
Speed of rotation (faster the rotation, higher the frequency output)
209
What is a CSD?
Constant speed drive
210
What is a CSD for?
Ensures generator maintains its designed operating RPM irrespective of change in engine speed
211
How does the CSD operate?
Hydraulically and has its own oil reservoir
212
Once disconnected, when can the CSD be reconnected?
Only once on the ground
213
When a CSD is disconnected, what are the indications?
CSD low oil pressure light
Frequency 0
Voltage 0
214
What is done to prevent accidental turning off of the CSD?
Guarded red switch
215
What is normal output for AC generator?
115v 400 Hertz
216
How are power ratings of AC generators expressed?
kVA
217
What is a Bus in the electrical system?
Point receiving current from generator or battery for distribution users
218
What is a split bus system?
One generator supplies a bus at a time
219
What is a parallel generator system
Multiple generators may be connected to one bus
220
Can external power sources be parallel?
No
221
What happens to generators and external power once engine is started?
Generator breaker switch is selected to close, external power on that side will automatically trip and incoming generator will assume load
222
What is the job of the TRU?
Transformer rectifier unit.
| Transforms 115V AC to 28 VDC with use of diodes
223
What happens if essential power fails?
Standby busses automatically isolated from essential busses.
| Battery energises inverter which supplies 115 V to standby AC bus
224
What are trip free circuit breakers?
Always free to trip in overload condition regardless of reset button
Cannot be overridden
225
What are non trip free circuit breakers?
May be overridden by depressing the reset button even if fault exists
226
What is a bus tie switch?
Control bus tie breaker which joins two or more busses together to provide generator redundancy in parallel electric system
227
What does a transformer do?
Reduces voltage of AC
228
What does a rectifier do?
Converts AC to DC using diodes which allow current to flow in one direction
229
What does a static inverter do?
Converts 28V DC to 115V 400 Hertz AC by use of transistors
230
Once employed, when can RAT be stowed?
Only once on ground
231
What are pilot exciters?
Small generator built in to large generator which provides initial field excitement until main generator is self sustaining
232
How is battery capacity measured?
Amp hours
233
What is a battery in series?
Battery connected in series (positive to negative) which increases VOLTAGE at constant current (amp)
234
What is a battery in parallel?
Battery connected in parallel (positive to positive or negative to negative) which increase total CURRENT (amps) at constant voltage
235
How are batteries generally charged?
Constant volts at reducing current
236
Why do lead batteries need to be vented?
They give off explosive mixture of oxygen and hydrogen when being charged
237
What are the advantages of NiCad batteries over lead acid?
Lighter and tougher
Don't give off as much dangerous gas
Faster recharge
More useful capacity
238
What are the disadvantages of NiCad batteries?
Higher purchase cost
Reduced capacity if not fully charged
Increased risk of thermal runway
239
What is thermal runway?
During charging where battery overheats and electrolytes boil. Gas is released and plates melt resulting in battery damage and perhaps explosion
240
How are NiCad batteries protected against thermal runway?
Vented battery compartments
| Battery temp sensors
241
What is the fluid reservoir?
Stores supply of hydraulic fluid and must be sufficient to operate system and to supply reserve in case of emergency.
Replenishes fluid lost to leaks
242
What happens before hydraulic fluid returns to the fluid reservoir?
Passes through a filter where it is cleaned and cooled.
| Purged of bubbles
243
What are baffles used for in the fluid reservoir?
Prevent foaming
244
Why is the reservoir vented?
To allow air to replace volume of fluid
245
What does the pressure relief valve do?
In the event that pressure regulator becomes inoperative and system pressure increases above designed max, PRV will open and allow excess fluid to return to reservoir
246
What is the shuttle valve?
Allows alternate system to pressurise the lines and provide system ops if primary pump fails
247
What are priority valves?
Automatically shut off supply to non essential services in event of hydraulic leak
248
What are accumulators in the hydraulic system?
Dampen out pressure pulsations (primary)
| Store hydraulic fluid under pressure
249
At low speed, if full right aileron is applied, what happens to left and right wing?
Left wing inboard and outboard ailerons are deflected down
| Right wing inboard and outboard ailerons deflected up. Right wing spoilers deflected up
250
How are speed brakes controlled?
Hydraulically controlled
251
What does deployment of speed brakes do?
Increase drag
Dump lift
Transfers weight to the wheels for better braking
252
What is the deflection angle for rudder within APU?
0-25 degrees
253
What is the reason for a moveable stabiliser?
Avoids prolonged deflection of elevator tabs and associated trim drag
Requirement for trim or large changes in CoG
254
What does the auto stab trim system do?
Senses elevator input signals
| Trims stabiliser to fair the elevators
255
If the pilot has extended the flaps to landing config, and the IAS increases to flap limit speed, what happens?
Flap load limit relief system hydraulically and automatically retracts flaps to safe setting. FLAP LEVER DOES NOT MOVE
256
How are leading edge devices operated?
Hydraulically or pneumatically
257
What is EICAS?
Engine Indicating and Crew Alert System
258
When does the stick shaker operate?
Approx 7% higher than stall speed
259
What is PCN?
Pavement classification number
| Strength of pavement
260
What is ACN?
Aircraft classification number
| Weight of aircraft on pavement
261
What is the crews responsibility with regards to PCN and ACN?
Must ensure ACN does not exceed PCN
262
Where is the safety squat switch?
On the gear oleos
263
What does the sequencing valve do with regards to gear retraction?
Makes sure components operate in correct order.
Door open
Gear retracts (gear doesn't retract till door full open)
Door closes (doors don't start to close until gear fully retracted)
264
How do you turn with regards to nose gear steering?
Hydraulic system pressure
| Tiller and pedals
265
When is tiller used? When are rudder pedals used for steering?
Tillers used for sharp turns
| Rudder pedals to maintain directional control during TO and Landing
266
What happens to nose wheel after take off?
Centring mechanisms automatically centre nose wheel
| essential to retract the wheel
267
What does the follow up linkage do with regards to steering mechanism?
Returns steering to neutral and holds correct angle of turn
268
What is one advantage of tilting trucks?
Allows to fit smaller wheels
269
What happens when trucks untilt after touch down?
Change aircraft systems back to ground mode ops
270
What defects can prevent main gear from retracting safely?
Body gear steering not centred
| Main gear not tilted correctly
271
If the hydraulic fails, how do we extend gear?
Alternate gear extension sequence
Door opens
Gear unlocks allowing it to freefall to extended
Gear locks in position
272
Is there an alternate selection for retraction of gear?
No
273
If the green light doesn't come on for gear down, how do pilots determine which gear is faulty?
Use EICAS or flight engineers module
274
What is the tiller steering angle?
0-65 degrees
275
What does the anti skid system do?
Continuously seeks level of correction of brake signal which produces max braking which is just short of skidding
276
What is a lock out valve on the brakes do?
Prevents one leaking brake line from causing loss of entire hydraulic system . Closes and isolates leak
277
If the auto brake system is engaged, what happens if the pilot uses manual brakes?
Autobrake is disengaged
278
How long does auto brake provide braking?
Until complete stop or until disarmed
279
What are the selections for auto brake?
1,2,3,4,MAX
280
Which provides more braking, Max on auto brake or max manual braking
Max manual braking
281
Which provides more braking, Max on auto brake or RTO?
RTO
282
With auto brakes engaged, when will RTO autobrake operate?
If thrust is retarded to idle above 85kts during take off
283
How is the auto pilot system disengaged?
Manual braking
Change selector to OFF or DISARM
Stowing speed brake lever before deployment on ground
Advancing thrust above idle
284
What are fusible plugs in the wheels for?
Melt at high temperatures and deflate tyres to prevent explosion
285
What happens if the fusible plugs melt?
Wheel MUST be replaced
286
When is manual reversion required?
If triple redundancy is not provided (three independent systems)
287
What is q feel?
Artificial feel for powered controls
| based on airspeed
288
What do spoilers assist with?
Roll control and inflight speed brakes
289
What does variable incidence tail plane do
Assist elevator and for pitch trim
290
What do fowler flaps do ?
Increase SA
291
What do slotted flaps do?
Energise boundary layer
Delay stall
Allow higher body angle on approach
292
Why are tricycle undercarriage better than tail wheel?
Greater braking potential
Higher landing speeds
Less tendency to ground loop
Better visibility during take off and taxi
293
Which provides greater angle of nosewheel deflection, tiller or rudder?
Tiller
294
What does bogie configuration do?
Allows lower tyre pressure and therefore lower ACN
295
What conditions require tyre to be replaced?
Thermal plugs melting
| Bulge in tread or sidewall
296
What is the primary purpose of the chine or ribs on tyres?
Deflect water away from engines
| Secondary purpose to assist against hydroplanning
297
What does anti skid system do?
```
Normal skid control
Locked wheel skid control
Touchdown protection
Hydroplane protection
Failsafe protection
```
298
What does normal skid control do?
Prevents wheel from locking by relieving brake pressure if skid detected then reapplying pressure when wheel speeds ip
299
What does locked wheel ski control do?
Fully released brakes
300
What does touch down protection do
Prevents brakes being applied prior to landing by air/ground logic switch
Wheel speed must be 20kts before brake pressure applied
301
What does fail safe protection do?
Disables system in event of fault
302
What does modulator valve do in anti skid system?
Decrease pressure pulses
| Felt as shutter in pilot toe braking
303
What is the formula for hydroplaning ROTATING wheel?
9 x Square root tyre pressure
304
What is the formula for hydroplaning non rotating wheel?
7 x square root tyre pressure
305
Name some systems that rely on pneumatics for operation?
```
Air con/pressurisation
Wing and engine anti ice
Engine cross bleed start
Hydraulic reservoir pump
Air drive hydraulic pump
```
306
When the engine is low thrust, what happens to HP valve?
Opens allowing high pressure air to power system
307
When thrust is increased what happens to HP valve?
Closes and LP check valve opens to supply bleed air
308
When can ice form?
When OAT and TAT (total air temp) in flight is 10 degrees or below and visible moisture
309
Where is bleed air provided to for anti icing?
Engine
Wings
Antennas
310
What does use of bleed air for anti ice do to engine?
Imposes heavy demand
311
How are props on turbo props de-iced?
Electrically on a phased cycle
312
What are the types of ground anti/de icing?
```
Type 1 (unthickened fluids)
Type 2 (thickened fluids)
```
313
Which fluids are used for deicing generally and why?
Type 2
| Type 1 have low viscosity and therefore only protect wing for short time.
314
What must you do to the EPR during engine bleed air anti ice operation?
Reduce maximum EPR
315
When must engine anti ice be on?
During all ground and flight ops when icing conditions exist or are anticipated
316
How is ice detected?
Sensor on the nose that displays warning on EICAS
317
What protection is there for the windscreens in terms of anti ice?
Electrically heated anti ice and anti fog
318
When is anti fog used on windshields and when does it run with regards to window heat?
Continuously and is independent of window heat
319
Should rain repellent be used on a dry windscreen?
No, smears and reduces forward visibility
320
What is the ventilation rate, temperature and minimum relative humidity for pressurised cabin?
One lb of air per person per minute
18-24 degrees
Relative humidity 30%
321
When will cabin altitude warning horn sound?
If cabin altitude exceeds 10000ft
322
When do emergency masks drop?
If cabin altitude exceeds 14000ft
323
What is the differential pressure
Difference in cabin pressure and atmospheric pressure
324
How is the cabin altitude regulated?
Cabin pressure controller
325
What does the cabin pressure controller do?
Signals outflow valves to spill more or less air overboard to maintain nominated cabin altitude (in isobaric control) OR a nominated differential pressure during cruise
326
On climb or descent, how is cabin pressure rate of change maintained?
Proportional to rate of climb or descent
327
What is required to be entered by the crew for the automatic mode of the cabin altitude?
Initial cruise flight level
| Landing airfield elevation
328
When is standby mode used for cabin altitude?
Used in event of auto mode failure
329
What happens in standby mode for cabin altitude?
Cabin altitude is selected relative to proposed cruise altitude by referring to placard and desired cabin rate of change is also selected
330
When would a fully manual mode be used for cabin altitude?
In event
331
How is exceeding the maximum positive pressure differential prevented?
Positive pressure relief valve
332
What does positive pressure relief valve do?
Relieves cabin pressure in event of failure of normal outflow valves or incorrect setting
333
What does negative pressure relief valve do?
Opens to allow air INTO the cabin from outside if air pressure exceeds cabin pressure
334
How is the cabin pressurised?
Bleed air supplied to and distributed by air con system
335
What PSI is the max differential pressure the pressure relief valves limit the system to?
8.65PSI
336
When do the negative pressure relief valves open?
-1.0 PSI
337
What are the selections for cabin pressure?
AUTO
STBY
MAN AC
MAN DC
338
What are the two types of aircon systems/
Vapour and air cycle
339
What does the air con do to the bleed air before it enters the cabin?
Must cool it
340
What does the vapour cycle air con consist of?
Compressor
Evaporator
Condenser
341
What does the air cycle do?
Compresses and expands the air to extract heat and achieve cooling
342
What are the advantages and disadvantages of air cycle system?
Advantages: Simple and light
Disadvantages: Less effective than vapour, poor cooling on ground
343
What does basic air cycle system consist of?
Engine bleed air
Heat exchangers
Turbine
Compressor
344
Describe how the air cycle work?
Bleed air cooled by ram air through primary heat exchanger
Compressed by compressor driven by turbine
Passes through secondary heat exchanger and again cooled by ram air
Passes through turbine, further cooled and expanded
345
What is the temperature of the air fed to the cabin regulated by?
Air mix valves
346
What are air mix valves?
Regulate temperature of air to cabin
| Mixes cold air with bleed air to achieve desired temp
347
What do ram air doors do in the air cycle machine?
Cooling of aircycle
| Vary the volume of ram air passing through heat exchangers
348
What do humidifiers do in air cycle
Spray a mist of water into conditioning duct leading to cabin.
Maintains 30% humidity
349
On the ground, what does the air cycle system need?
Ram air flow needs augmentation from a bleed air powered turbo fan in the ram air duct
350
Why is air recirculated?
To reduce bleed load on engines and therefore save fuel
351
What is the 'cost' of recirculating air?
Degrades air quality
352
What is the ram air valve for?
Opened to allow outside air into cabin directly to provide ventilation and smoke removal.
Supplies air into main air supply ducts for delivery into the cabin but only for unpressurised flight
353
Bleed air from the pneumatic duct through each air con pack is controlled by what?
Independent left and right pack
354
What happens if one of the air con packs fails?
The other pack is able to take the load
355
Where does the left pack get its air from and supply it to?
Engine 1
| Supplies to cockpit
356
Where does right pack get its air from and supply it to?
Engine 2
| Supplies to Cabin
357
How long do cockpit voice recorders cycles last?
30 minutes
358
How long do FDR cycles last for?
approx 25 hours
359
Where are FDRs located?
In the tail plane
360
What forces must a black box be able to withstand?
```
3400G
500lbs weight from 10 ft
1100 degrees for 30min
260 degrees for 10 hours
30 days in water = 20000ft
30 days in salt water
```
361
When do CVR operate?
From start of first checklist and retain last 30mins of recording
362
How long must the FDR record for?
From time aircraft moves under its own power to time it comes to stop and retain last 25 hours of recording
363
When selector is in AUTO position, which computer is used for EICAS CRT?
Left
364
When selector is in AUTO position, and the left computer fails which computer is used for EICAS CRT?
Right
365
What would be in the primary EICAS CRT?
N1
EGT
EPR
366
What would be in the secondary EICAS CRT?
N2
Fuel Flow
Oil quantity, temp and pressure
367
What does a red message mean on EICAS?
Warning message
368
What does an amber message mean on EICAS?
Caution or advisory
369
What does a cyan message mean?
Status Cue
370
What is a warning?
Requires prompt corrective action (i.e. engine fire)
371
What is caution?
Requires timely action (engine overheat)
372
What is an advisory?
Requires corrective action on time available basis. (yaw damper fault)
373
What does a bell indicate?
Fire warnings
374
What does a siren indicate?
Cabin altitude, autopilot disconnect, config and overspeed warnings
375
When do aural warnings automatically silence
When non normal condition no longer exists
376
When is the take off config warning armed?
When ac on the ground and EITHER engine accelerates towards take off thrust
377
What conditions will cause take off config warning to go off?
Leading or trailing edge slats/flaps not in take off position
Slat/flap disagrees with flap lever position
Stabiliser position out of TO range
Spoiler lever not down in detent
Position parking brake valve closed
378
When is the landing configuration warning go off?
Plane below 800ft radio altitude and either thrust lever set to idle with gear up
Landing flaps selected with gear up
379
What threshold is there for GPWS warnings?
50-2450 radio altitude
380
When does the overspeed warning go off?
When Vmo/Mmo limits are exceeded
381
What are the 5 different modes for GPWS warning?
Mode 1 Excessive descent rate
Mode 2 Excessive terrain closure rate
Mode 3 Altitude loss after take off/go-around
Mode 4 Unsafe terrain clearance while not in landing config
Mode 5 Below glide slope deviation
382
Which modes provide WHOOP WHOOP warnings?
Mode 1 and 2
383
What is the aural alert and aural warning for mode 1?
Sink rate
| WHOOP WHOOP PULL UP
384
What is the aural alert and aural warning for mode 2?
Terrain
| WHOOP WHOOP PULL UP
385
What is the alert for mode 3?
Don't Sink
386
When is mode 4A armed?
After take off climbing through 700ft
387
When is TOO LOW GEAR warned in mode 4A?
Below 190kts when passing through envelope
388
When is TOO LOW TERRAIN warned in mode 4A
Above 190 kts when passing through envelope
389
What happens between 190 and 250 kts in mode 4A?
Envelope extended to 1000 ft
390
What happens when envelope is penetrated below 154kts in 4B?
TOO LOW FLAPS
391
What happens when envelop is penetrated above 154 kts in 4B?
TOO LOW TERRAIN
392
What happens between 154 and 250kts in 4B?
Envelope extended to 1000ft
393
When does Mode 5 alert go off?
Descent of more than 1.3 dots below glideslope
394
On the TCAS, what would +02 mean?
Aircraft is 200feet above
395
On TCAS what would -14 mean?
Aircraft is 1400 below
396
On TCAS what would a down arrow represent?
Aircraft descending more than 500fpm
397
On TCAS, what would an up arrow represent?
Aircraft climbing more than 500fpm
398
What would a amber filled circle represent on TCAS?
TA warning
| Aircraft within 40s
399
What would a red filled square represent on TCAS?
RA warning
| Aircraft within 25 s
400
Apart from aural warning, what happens with RA warnings?
RA pitch restriction appears on EADI
401
What warnings overrides TCAS warnings?
GPWS
Stall
Windshear
Low radio altitudes
402
What happens to RA when operating in TA ONLY mode?
They appear as TA's
403
How do autopilots work?
Employ closed loop control systems which sense deviations from steady flight path and apply corrections via control proportional to rate of deviation
404
How would an attitude change about on of the principal axes be sensed?
By the gyro
405
What does the gyro do in the autopilot?
Sense attitude change about axis.
| Process and produces output signal proportional to rate of change
406
What does the 'controller' do in the autopilot?
Compares gyro signal with fixed "reference attitude" and transmits suitable corrective signal to flying control servomotor
407
When is the autopilot loop closed?
When corrective action is sensed by gyro
408
How many autopilot channels are engaged during auto land?
all of them (2 or three)
409
Where does FMS receive data from?
Flight control computer
Air data computer
Thrust management computer
EICAS
410
What is CADC used for?
Computing IAS, TAS, Mach number, pressure altitude
411
What are CADC outputs used for?
Automatic speed
Rate of climb/descent
Altitude control
Mach trim control
412
What do series connected servomotors do?
Move control surface without moving pilot control
413
What do parallel connected servomotors do?
Move control surface AND pilot control
414
What is fail passive in autoland?
When 1 of the two autopilot channels fails during approach
Failure doesn't result in significant out of trim position.
Pilot assumes control of landing
415
At what height during autoland is localiser and glideslope beam captured during autoland with triple redundancy?
1500ft
416
At what height during autoland with triple redundancy is nose up altitude auto trimed?
330 ft
417
At what height during autoland with triple redundancy is flare?
50 ft
418
At what height during autoland with triple redundancy is flare disengaged?
5 ft
419
If engine fails during auto thrust, do you need to engage thrust? Why/why not
No.
| Reduced thrust is sufficient to ensure obstacle clearance and climb performance in event of engine failure
420
Radio altitude is displayed digitally below which height?
2450 ft AGL
421
TCSA symbols can be superimposed on displays for all but what modes?
Plan
422
Map mode displays track as what?
Magnetic track up
423
Plan mode is orientated how?
True north
424
VOR and ILS are orientate how?
Heading up
425
How would a FMC failure show up?
Map flag when in MAP mode
| FMC FAIL on CDU
426
What does green symbol mean on EFIS?
Engaged flight mode
427
What does white symbol mean on EFIS?
Present status situation
428
What does magenta symbol mean on EFIS?
Command info, pointers, symbols, fly to, active waypoints
429
What does cyan symbol mean on EFIS?
Non active/background info
430
What does red symbol mean on EFIS?
Warning info
431
What does Amber symbol mean on EFIS?
Cautionary info, faults, flags, limits, alerts
432
How is weather displayed?
With EHIS selected to MAP
| EHSI with expanded ILS or expanded VOR by selecting WX
433
How are CDUs connected?
In parallel
434
What are boxes on the FMC?
Data entry REQUIRED/ESSENTIAL for FMC operations
| e.g. gross weight, flight level
435
What do dashes represent on FMC?
Data entry not mandatory but will assist if entered
| e.g. forecast wind
436
How often is the navigation database updated?
28 day cycle
437
Where can the pilot check if the navigation data base is current?
IDENT page of CDU
438
Which pages is used to enter V speeds?
Takeoff page
439
Where can waypoints be entered
Route page
440
How do you enter waypoint not in FMC?
Lat and long place bearing/dist/place bearing/bearing
441
What happens to LNAV and VNAV when using standby navigation?
They are inoperative
442
What is SAR formula?
TAS / Fuel flow(fuel burn)
443
What thermocouple probes are used in turbo props?
Rapid response probes
444
What thermocouple probes are used in turbojet and turbofan?
Stagnation type
445
How does APU start?
Bleed air from engine
| Engine intake air ducted to compressor after which some is bled off
