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Flashcards in Exam Revision Deck (341)
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1
Q

What is a wire and what is it’s purpose?

A
  • Single insulated electrical conductor
  • Distributes power
2
Q

What is meant when referring to a wires shielding? What does it do?

A

Generally copper shielding material prevents electromagnetic interference (EMI) between sensitive circuits

3
Q

What is a cable?

A

Two or more insulated electrical wire conductors

4
Q

What is the ‘norm’ for a bundle common of wires?

A

May be twisted together or contained in common outer covering of insulation or shielding material, over which can be additional outer insulating jacket

5
Q

What does a co-axial cable do?

A

Supply RF energy signals from antenna to avionics systems

6
Q

What are some systems that use the co-axial cable?

A

VHF COMMS, LRRA, DME, ATC, VHF Nav

7
Q

Is co-axial cable one way or two way signal?

A

Two way signal

8
Q

What does a thermocouple wire do?

A

Constructed of special materials required for use in EGT systems

9
Q

Why are cables twisted?

A

To prevent extraneous magnetic field interference between sensitive circuits or systems

10
Q

Why are there multistranded wires?

A

If one wire breaks, it is still connected

11
Q

Where is tin coated conducted wire not used? Why?

A
  • Fuel circuits due to fuel corroding wire
  • In areas where it can be exposed to operations and elevated temperatures, corrodes.
12
Q

What sort of conductors are used in conditions of elevated temperatures?

A

Nickel plated copper conductors

13
Q

What is the advantage of using multistranded aluminium conductor wires?

A

Saves weight

14
Q

Where would you not use aluminium conductor wires?

A

Areas where there is high vibration

15
Q

Where are aluminium conductor wires usually used?

A

Within the pressurised fuselage

16
Q

What sort of wiring insulation material must be used?

A

Must be such that no toxic fumes evolve in event of wire failure

17
Q

What is Flemmings Law?

A

Cancels out magnetic field by having two wires with return path back to source

18
Q

Why don’t companies ‘hot stamp’ wires/cables anymore?

A

Hot stamping can potentially damage wires/cables

19
Q

How do Boeing number stamp their wires?

A
  • Specific bundle ID number (e.g. W242)
  • Specific sequential number (e.g. 001 to 999)
  • Gauge of wire (e.g. 22 or 20) W242-001-22
20
Q

What sort of system does Airbus use to number stamp its wires?

A

Air transport Association (ATA) system

21
Q

How does Airbus number it’s wires?

A

Unique code dedicated to different system (i.e. 23 = comms, 10=HF/VHF) followed by sequential number of wire followed by gauge. 2310-899-22

22
Q

What questions should be asked before installing a wire?

A
  • What wire gauge
  • Is it in a SWAMP area (severe wind and moisture problem)
  • Is it subject to corrosion (fuel or hydraulics)
  • Does need additional insulation
  • Does it need to be shielded temperature range exposed to (-65 to 150)
23
Q

What should be done with regards to installing bundled wires?

A
  • Prevent electrical interference with other bundles
  • Not interfere with any moving control systems
  • Have at least 12 mm clearance from any hydraulic line/pipe
  • Clipped to secure bundles to airframe or power plant to establish clearance
  • Installed and protected in metal conduits or fibre glass raceways to prevent chaffing
  • Sleeving to prevent chaffing from vibration
  • Wires routed so bends dont exceed minimum bend radius of wire (10x outside diameter of largest wire/cable in bundle)
24
Q

How are wires/cables etched with id number?

A

UV laser etching or plastic sleeving that are indelibly

25
Q

Why is polyvinal chloride insulation (PVC) not used on wires/cables?

A

Releases toxic fumes when wire broke

26
Q

What is a disadvantage of using kaplon wiring/cable insulation?

A

Can exhibit circumferential cracking when acceptable bend radii exceeded.

27
Q

What are good types of insulators for wires/cables?

A
  • PTFE
  • Kapton
  • ETFE
28
Q

What is the first thing you should check before replacing a wire?

A

The wire diagram manual to find preferred wire/cable type

29
Q

What would you need to do if you wanted to use a wire not in the WDM?

A

Seek approval from CASR 21.009 and/or CASR 21.437 CASA delegate

30
Q

When replacing a wire, what should you do with regards to the WDM?

A
  1. Check the wire list (contains info on every wire used in the aircaft as well as manufactures preferred type of wire/cable)
  2. If wire/cable isn’t on wire list, check the Alternate wires/cables section
  3. If not on that list, need to get CASR 21.009 and/or CASR 21.437 approval
31
Q

What must be checked with the connectors/receptacles?

A

That the pins & sockets are the correct size

32
Q

Why are solder connections not used any more?

A

It can run down the wire and lead to wire losing flexibility

33
Q

What is grounding?

A

Terminations that require connection to airframe

34
Q

What considerations are needed for clamping?

A
  • wire bundles properly supporte
  • properly sized and correct material type
  • spaced correctly for environement
  • mounted correctly
35
Q

What is routing?

A

Adds wires needed to connect components

36
Q

Why is routing important?

A
  • Eliminates chaffing
  • Makes sure correctly located with respect to proximity to fluid lines
  • Correct bend radii
  • Protection against cargo damage and/or maintenance damage
  • Adequate access for repair/maintenance
37
Q

What must be placed inside metallic conduit?

A

Teflon sleeving over wires

38
Q

Why is an AC (alternating current) preffered to a DC (direct current) system?

A
  • It is simpler, cheaper and more efficient than DC generator to produce same voltage level
  • permits the use of transformers to change voltage (either higher or lower)
  • Frequency of oscillation (more efficient)
39
Q

What is the CSD?

A
  • Constant Speed Drive
  • Hydromechanically operated gear transmission system that couples engines accessory gearbox to Generator
40
Q

What does the CSD do?

A
  • converts variable engine speed of accessory gear box to constant speed for driven generator to produce AC electrical power at constant frequency
41
Q

How does the CSD maintain constant speed?

A

It has a governor to maintain approx 6000rpm

42
Q

In the event of CSD/generator malfunction, what can pilots do?

A

Disconnect generator drive from engine accessory gear box via switch

43
Q

After disconnection, when can we reconnect CSD/Generator?

A

Only on the ground

44
Q

How can we monitor the ‘health’ of the CSD?

A

Low Press (pressure) and Temp indicator warnings in the cockpit

45
Q

What sort of power does the generator provide?

A

115 +/- 3 Volts

400 +/- 5 Hz

46
Q

Why do we use 400Hz?

A
  • Chose for weight saving purposes.
  • frequencies above 400Hz cause skin effects (current flow not evenly distributed)
47
Q

How is the generator cooled?

A

Cooling supplied to Generator by ducting from engine fan air

48
Q

What are the advantages of three phase vs single phase in ac generation systems?

A
  • Can be operated at slower speeds to produce same power
  • Peak voltages seperated by 120 degrees and not 360 = steadier power output
49
Q

In the generator, what is the ‘neutral’ point connected to?

A

Connected to the ground

50
Q

What is the volt ampere rating?

A

Max amount of energy (current) that generator can supply to demands of electrical and avionic services

51
Q

How much volt ampere can generator supply?

A

45kVA, note the maximum load is 50kVA however this is never demanded from generator.

52
Q

What is the purpose of the Generator Control Unit (GCU)?

A
  • Provides automatic operation of control functions of each generator system
  • provides signal to ‘trip’ the generator control breaker (GB) (trip = open circuit/take off line)
  • regulates generators voltage and limits amplitute of generators phase voltage under fault conditions
53
Q

What does the GCU protect the generator from?

A
  • Overvoltage (127-133 volts- gb trips)
  • Undervoltage (within 5-9 s of dropping below 93-103 volts, gb trips)
  • Overfrequency (425-435Hz, gb trips)
  • Underfrequency (360-370, gb trips)
  • Differential feeder faults (difference between phases exceeds 20 amps, gb breaks)
  • Over current (if total load on Generator exceeds 170-175amps, after time delay, GB trips)
54
Q

What does “BUS OFF” indicate?

A

When either GEN or APU GEN (aux power unit) is not supplying the GEN BUS

55
Q

What does GEN OFF BUS light indicate?

A

When GEN is not supplying its GEN BUS

56
Q

What does TRANSFER BUS OFF indicate?

A

When transfer bus is not powered by GEN BUS

57
Q

What is a relay?

A

Electromagnetically operated mechanical switch, when current applied to coil, arm moves and completes circuit.

58
Q

What happens if any generator fails?

A
  • That generators bus won’t be supplied with 115volts
  • APU can be started and supply that GEN BUS
59
Q

Why do we have automatic bus transfer system?

A

It increases electrical power reliability, i.e quicker response time in supplying failed bus

60
Q

Why does APU not have a CSD?

A

After completion of APUs starting cycle, drives generator at constant speed of approx 6000rpm

61
Q

What is the main difference between 747 and 737 power generation systems?

A

Very similar, it has four 115V ac 3 phase, 400Hz except it can supply up to 90kVA loads

62
Q

How many integrated drives and generators (IDG’s does 747 have and how are they connected?

A

4 and in parallel

63
Q

How many engine driven generators does an A380 and what is their output?

A

4 and 150kVA each

64
Q

How many APU generators does an A380 have? And with what output capability?

A

Two and 150kVA

65
Q

While the A380 power system is fully computerised, how does 737 and 747 GCU control their generating systems?

A

Transistor circuits

66
Q

How many ac generators does a 787 have?

A

2 per engine 250kVA each

2 on APU 250kVA each

67
Q

What can static electricity interfere with?

A

HF and Nav (ADF in particular)

68
Q

What does bonding do?

A
  • Ensures aircraft is of same electrical potential
  • Metal parts electrically connecte to conductive structure
  • Non metal parts bonded to ac structure via conductive return path (conductive paint, aluminium strips, stainless steel mesh)
69
Q

What in the aircraft is bonded?

A
  • All control surfaces
  • Avionics racks
  • Circuit ground terminals
  • Radio/NAV antenna
  • Galley
  • Fuel lines
  • Hydraulic lines
70
Q

What can inproper bonding lead to?

A
  • Radio/comms interference
  • injury
71
Q

What is the purpose of bonding?

A
  • Protect from lightning strikes
  • Current return paths for electrical/avionic circuits
  • prevent development of RF potentials
  • protect from electric shock
  • prevent interference with radio
  • prevent accumulation of static charges
72
Q

What is the basic bonding process?

A
  1. Clear area of paint/con-conductive finishes and corrosion
  2. Protect area using alodine
  3. Establish bond
  4. Measure bonding resistance
  5. Surface around the bond re-painted
73
Q

What is the purpose of the HF Comm system?

A
  • Provide comms link between flight crew and ground
  • HF Data Links (HFDL)
74
Q

At what hert does HF comm system transmit/receive?

A

2-30 MHz

75
Q

What is HFDL?

A
  • HF Data Links
  • Worldwide comms between ac and ground
  • works over north pole
  • Lower cost than SATCOM
76
Q

What do a HF Comm system consist of?

A
  • Receiver transmitter (RT)
  • Antenna
  • Antenna Coupler
  • Control Panel
  • Remote Electronic Unit
77
Q

What does the RT do?

A
  • Provides transmit signal and power to antenna at selected frequency
  • Processes received signal from signal at selected frequency
  • provides AM, Single Side Band Mods, Voice and Data Comms
78
Q

What does antenna do?

A
  • Radiate transmitted RF energy it receives from RT
  • Receives RF energy directed to ac from ground
79
Q

What determines the efficiency of the antenna?

A

Length and/or postion of antenna

80
Q

What sort of aircraft is a fixed wire antenna attached to?

A

Slower turbo prop and jets

Piston ac

81
Q

What are the advantages of notch/shunt antenna over fixed wire?

A
  • It’s flush and has no impact on structure leading toreduced drag and less weight
  • Doesn’t require lightning protection
82
Q

Where is the antenna coupler located?

A

Vertical Stabiliser

83
Q

What does the antenna coupler do?

A

Matche antenna impedance to RT over HF range

84
Q

What does the Antenna coupler tune the antenna to?

A

50 ohms

85
Q

What does the control pannel consist of?

A
  • On/Off switch
  • Mode Selection (USB/LSB or AM)
  • Frequency selection (1 and 10 kHz)
  • RF sensivity
86
Q

What is the signal/noise ratio?

A

Ratio between magnitude of signal to background noise

87
Q

Which is better, high or low signal to noise ratio?

A

High

a low s/n has hiss and static

88
Q

Which is more efficient, AM or USB/LSB and why?

A
  • USB/LSB, they use less power to carry modulating signal
  • Provides greater range (uses all transmitter power to convey voice info)
  • Clearer speech
89
Q

What does Amplitude modulation consist of?

A

Carrier frequency and corresponding side band frequencies

90
Q

What does Upper side band consist of?

A

Carrier frequency plus modulating frequency (FC + FM)

91
Q

What does Lower side band consist of?

A

Carrier frequency minus modulated frequency (FC-FM)

92
Q

What does the REU do?

A

Process all radio audio signal from each crew station

93
Q

How is the HF propagated?

A
  1. HF Signal leaves antenna and remains near surface (ground wave)
  2. Sky wave leave antenna and goes up into ionosphere, then reflects signal back to certain frequencies (skip)
94
Q

Define Maximum usable frequency?

A
  • Highest transmitted frequency that is reflecte back to earth
  • Signal absorbed the least
  • gives greatest reflection back from ionosphere
95
Q

Should you use HF when refuelling?

A

No

96
Q

What frequency should you use during day and night?

A

10-30 during day

2-10 during night

97
Q

How does VHF operate?

A

Uses line of sight (no ionosphere propagation)

98
Q

What frequency range does VHF go from?

A

118.000 to 136.975 kHz

99
Q

What sort of spacing is there between channels?

A

25kHz spacing = 760 channels

Some parts of Europe and US, 12.5kHz spacing 1520 channels

100
Q

How does VHF transmits its radio waves?

A

AM techniques

101
Q

What are some advantages of VHF over HF?

A
  • Offers least amount of interchanel interference
  • Smaller antenna
  • more efficient power trasnmitted from RT to ground receiver
102
Q

What sort of antenna is both HF and VHF?

A

Omnidirectional

103
Q

What range does VHF have?

A

120nm @ 10000 feet to 245nm @ 40000feet

104
Q

Where are VHF Comm 1 and VHF Com 2 located?

A

VHF Comm 1 on top (incase of belly landing)

VHF Comm 2 on belly

105
Q

What is VHF Comm 3 normally dedicated to?

A

ACARS (Aircraft Communication Addressing and Reporting System)

106
Q

What is ACARS?

A

Simple digital messages to and from aircraft

Out/Off/On/In messages

107
Q

What does the following mean?

ADO733/0745 EA 0836 SYD

A

Out ADO0733

Off 0745

ETA for Sydney 0836

108
Q

How does HF data link differ from ACARS?

A
  • Provides coverage when out of VHF Range (i.e. oceanic and polar routes)
  • Transmitted to ground via SATCOM (or other satellite)
109
Q

How many volts are provided to DC system?

A

28 volts DC

110
Q

How is the 28 dc volts provided to DC power systems?

A
  • 3 transformer rectifier units (TRU)
  • Battery (nickel cadmium)
  • Battery charger
  • Cockpit control and indicator panels
111
Q

What does the TRU do?

A

Supplied with 115 Vac and converts it to 28 Vdc

112
Q

What is the advantage of 3 phase ac then rectifying and filtering?

A
  • Much shorter dc wave with less ripple voltage
  • Output of TRU is regulated and ensures constant voltage
113
Q

What is elements is the battery made up of?

A

Nickel and Cadmium (Ni Cd)

114
Q

What is the amp hour capacity on the average Ni Cd battery?

A

36 amp hour capacity

115
Q

What are the advantages of Ni Cd batteries over Lead acid type?

A
  • Better weight to energy ratio (NiCd lighter)
  • Can supply higher current demand and withstand higher charges
  • Has Longer life
  • more robust
116
Q

What are the disadvantages of the Ni-Cd battery? And what is done to assist?

A
  • Temperature sensitive during charging, so is fitted with a temperature monitoring device that goes off above 58 degrees
117
Q

Which is the negative and which is the positive element in a Ni-Cd battery?

A

Ni = positive

Cd = Negative

118
Q

What is ‘charging’ of battery?

A

Conversion of electrical energy into stored chemical energy

119
Q

What will a 25 ampere hour battery deliver?

A

25 ampere for a minimum of 1 hour

120
Q

What is the service life of a Ni-Cd battery?

A

250 hours

121
Q

What is supplied by the battery power?

A
  • Ground service ops (lighting) during refuelling
  • Starting of the APU
  • Last resource of electrical energy in event of total power failure
122
Q

What is electric load analysis?

A
  • Determines loads battery must supply
  • TIme battery endurance under emergency conditions is approx 40 mins
123
Q

How is the battery charged?

A

Supplied from 115 Vac Ground Service Bus (GSB)

Sensing circuitry determines charge state and provides rapid charge followed by pulsing charge

124
Q

When does the charge current cease? And why doesn’t it continue to charge?

A

When battery is considered by circuitry to be charged. Doesn’t continue to charge because otherwise cell voltage will rise with charging process and charge current requirements will fall

125
Q

What do TRU1 and TRU2 provide power to?

A

BUS1 and DC BUS 2

126
Q

Are TRU1 and TRU2 in parallel?

A

Yes

127
Q

What does TRU3 do?

A
  • Is a back up for either TRU1 or TRU2 in event of failure (provided BUS TRANSFER is in AUTO)
  • Main function to supply power to 28 Vdc battery bus (providing BAT SW ON)
128
Q

What is the alternate supply when 115V Main AC BUS 2 not powered?

A

Hot Battery Bus

129
Q

What happens when battery switch is selected to on?

A

Guarded switch goes down

28 Vdc batt bus normally supplied by TRU3 if 115 V Main AC bus 2 is powered

130
Q

What happens when battery switch is off?

A
  • Guard is lifted
  • No power is supplied unless Standby Power is in ‘BAT’ position
  • Prevents ignition of fumes
131
Q

What is it called when the battery is unservicable?

A

Total Discharge State

132
Q

Where is the Auxiliary Power Unit started from?

A

AC Battery on ground

133
Q

How much AC power via generator does Auxiliary Power Unit supply on ground and in air?

A

60kVA on ground and 50kVA in air

134
Q

What is Auxiliary power Unit powered directly from?

A

28 Vdc Hot Battery Bus

135
Q

How is the Auxilary power unit started?

A
  1. Battery charger disconnected from battery bia APU start interlock relay
  2. This realy prevent battery charger supplying any dc current via 28 Vdc hot battery bus for APU start
136
Q

In the event of an emergency, what systems powered by the battery?

A
  • VHF Com 1
  • Engine and APU Fire detectors and extinguishers
  • STBY FLT Instruments (ALT, IVSI and ADI)
  • STBY RUDDER FLT Control Hyd Valves
  • APU Starting
  • No1 IRS
  • Engine Fuel Shut off an Cross feed valves
  • Engine Wing anti ice
  • Landing gear indicator and aural warning
  • Engine ignition system via ac standing bus
137
Q

What is the purpose of the FDR?

A
  • To collect data that helps investigators in event of crash
  • Assist engineering with engine trend monitoring (vibrations or EGT monitoring)
  • picks up crew erros, external events or AC failures
138
Q

What were the original FDRs like?

A
  • Inconel steel foil (nickel cobult alloy)
  • could only record 5 parameters
139
Q

How many parameters coud the original FDR record and what are they?

A
  • 5
  1. Heading
  2. Airspeed
  3. Altitude
  4. Vertical acceleration
  5. Time
140
Q

How did the original flight data recorders, record their data?

A

Individual steel pens would inscribe on metal foil

141
Q

How many hours would the original FDR record for?

A

200 hours, after that they would need to be ‘flipped’

142
Q

What were the main problems with the foil fdr?

A
  • Impact withstand low, 100G
  • Fire survivability low
  • Foil jams
  • Foil tears
  • Loss of data when end of foil reached
143
Q

After foil FDR, what was the next generation of FDR like?

A

Magnetic recording tape

144
Q

After the foil FDR, how many parameters did CASA mandate?

A

20 new parameters

145
Q

How long did magnetic recording FDR record for?

A

25 hours

146
Q

What survivability does magnetic FDR have?

A
  • Fire survivability of 1000 degrees for 30 mins
  • Impact tolerance 1000G
147
Q

How many parameters could magnetic FDR record?

A

300

148
Q

Following an accident, where does the data from FDR go to?

A

ATSB

149
Q

What are the new FDRs like?

A
  • Use memory chips
  • Record >200 hours depending on digital flight data aquisition unit (DFDAU) to which FDR is interfaced
150
Q

What does the FDR consist of?

A
  • DFDR
  • DFDAU, collection point for ALL parameters
151
Q

What parameters are recorded?

A
  • ON/OFF
  • UP/DOWN
  • Auto pilot
  • Engaged/Disengaged

Plus many more

152
Q

How are parameters recorded?

A
  • Recorded as analog, digital or logic signal
153
Q

How are vertical, longitudinal and lateral acceleration sensed?

A

3 axis accelerometer

154
Q

What does the DFDAU do?

A

Passes data to DFDR in digital format

155
Q

What is the time fram for recording data in DFDR?

A

Frame = 4 seconds

Divided into 4 subframes each 1 second long

Data is presented to DFDR at 64 words per second (subframe) from DFDAU

64 words per subframe and 12 bit per word

156
Q

CAO 103.19 Appendix 1 states that vertical acceleration must be recorded at interval of 0.125 s, how many times is this recorded per second?

A

1 / 0.125 = 8

Recorded 8 times per second

157
Q

CAO 103.19 Appendix 1 states the squat switch must be recorded at interval of 0.5 seconds, how many times is it recored per second?

A

1 / 0.5 = 2

Recorded 2 times per second

158
Q

During the harvard bi-phase, if remains at +5V or -5V for the whole bit cell, what is this said to be?

A

a 0

159
Q

During the hardvard bi phase, if fluctuates from -5V to +5 V, what is this said to be?

A

A 1

160
Q

For the VA with 0.125s and 8 times per second recording, what is the best sampling method per 64 word/Second?

A

2, 10, 18, 26, 34, 42, 50, 58 and then recommence at 2 in SB2

161
Q

What is the survivability of the CVR?

A

Same as the FDR

162
Q

How long doe CVR record for?

A

30 mins of continuous recording, however the SSCVR records last 2 hours of flight before memory is over written

163
Q

What does the CVR actually record?

A

Pilot and Co-pilot audio

Observers audio

Area microphone

164
Q

When can the erase switch be used?

A

When no safety events have occured in last 30 mins when AC on ground

165
Q

How do you erase CVR?

A

Erase switch pressed for 2 seconds when on ground and park brake is set

166
Q

When is the FDR reasonableness check done?

A

Ever 2500 flight hours

167
Q

What is involved in a flight reasonableness check?

A

Tape assessed to make sure mandatory parameters plus the others are being recorded properly

168
Q

What is mandatory to be attached to the blackbox?

A

Underwater locator beacon

169
Q

What does the underwater locator beacon transmit at and how long does it last?

A

37.5kHZ and last for 30 days after activation

170
Q

What happens if the FDR fails on ground?

A

Plane cannot take off unless at an airport when maintenance of FDR cannot be done

171
Q

Why do we use logic circuits?

A

Because flight crew operations manual (FCOM0 use logic gates to show how complex systems function

172
Q

With logic gates, what is a low and what is a high?

A

Low = 0

High = 1

173
Q

With a low (0) what are the normal outputs?

A

False

Low

Off

Open

Open (switch not to ground)

Down

174
Q

With a high (1) what are the normal responses?

A

True

High

On

Closed

Close(switch to ground)

Up

175
Q

Describe the AND gate

A

Output is true when both inputs are true (1) otherwise it is false

X=AxB

176
Q

What picture represents the AND gate

A

Big D

177
Q

Fill in the blanks for this AND gate

Input 1 Input2 OUTPUT

0 0 ?

0 1 ?

1 0 ?

1 1 ?

A

0

0

0

1

178
Q

Describe an OR gate

A

Output is true (1) if either or both of inputs are true.

If both inputs are false, then output is false

X=A+B

179
Q

What picture represents the OR gate?

A

Big arrow

180
Q

Complete this OR gate

In In Out

0 0 ?

0 1 ?

1 0 ?

1 1 ?

A

0

1

1

1

181
Q

Describe an Exclusive Or (XOR) gate

A

Output is true if either but not both inputs are true. Output is false if both are false or both are true

182
Q

What picture represents the XOR gate

A

Line before a big arrow

183
Q

Complete this XOR gate

IN IN OUT

0 0 ?

0 1 ?

1 0 ?

1 1 ?

A

0

1

1

0

184
Q

Describe the inverter gate (NOT gate)

A

One input and one output

Output reverse logic state of input

185
Q

What picture represents the NOT gate?

A

Triangle with a ball on its tip

186
Q

Finish this NOT gate

IN OUT

1 ?

0 ?

A

0

1

187
Q

Describe a NAND (not and) gate?

A

Output is false if both inputs are true, otherwise it is true

188
Q

What picture represents a NAND gate

A

big D with a circle

189
Q

Finish this NAND logic gate

IN IN OUT

0 0 ?

0 1 ?

1 0 ?

1 1 ?

A

1

1

1

0

190
Q

Describe a NOR (not or) gate

A

Output is true if both inputs are false, otherwise output is false

191
Q

What picture represents NOR gate?

A

Arrow with a circle on point

192
Q

Complete this NOR gate

IN IN OUT

0 0 ?

0 1 ?

1 0 ?

1 1 ?

A

1

0

0

0

193
Q

What are the advantages of relay switch?

A

Can switch AC and DC

Can switch high voltages

Large currents

Many circuits simultaneously

Can use relatively low currents to operate relay coil

194
Q

What are the disadvantages of relay?

A

HEavier

Can’t switch rapidly

COnsumes more power

195
Q

An AND gate is connected in what? Series or parallel?

A

Series

196
Q

A OR gate is connected in what? Series or parallel

A

Parallel

197
Q

A triangle represents what on logic circuit?

A

Relay

198
Q

What does Ground Based Primary Surveillance Radar (PSR) determine?

A

Range and azimuth

199
Q

What frequency is the PSR?

A

2.7-2.9 GHz

200
Q

What is the down side of PSR?

A

Uses a lot of RF energy

201
Q

What does the secondary surveillance radar (SSR) do?

A

Assignes 4 figure ‘skin’ code.

AC can ‘squwark’ this code either manually or through automatic airborn system

202
Q

How does the ATC get squwark code?

A
  1. From the ground, P1 and P3 pulse trasmitted from rotating SSR towards AC at 1030MHz
  2. AC replies at 1090MHz
203
Q

What does the first set of P1 and P3 pulses do and what mode is this??

A

Requests IDENT code

MODE A

204
Q

What is the second set of P1 and P3 pulse requesting and what mode is this?

A

Requesting altitude

Mode C

205
Q

What is the third pulse and when does it occur?

A

P2 and 2 useconds after P1 pulse

206
Q

What antenna does P2 pulse come from?

A

Omnidirectional antenna

207
Q

What antenna does the P1 and P3 pulse come from?

A

Directional antenna

208
Q

What is the purpose of the P2 pulse?

A

Transmitted by SSR rotating antenna at 1030 MHz. Surpresses RF energy from interferring with ATC P1 and P3

209
Q

What is a side lobe?

A

Unwanted SSR RF energy

210
Q

By how much does the P2 pulse supress side lobes by?

A

-10db

211
Q

What is the altitude send as in Mode S transponder

A

1013 millibars in 100 ft increments

From -1000 feet to +126700 feet

212
Q

How does the Mode S transponder send IDENT?

A

F1 and F2 pulses transmitted at 1090 MHz

213
Q

What does Mode A transmit?

A

IDENT info

214
Q

What does Mode C transmit?

A

IDENT and ALT

215
Q

What does ALT SOURCE do?

A

Determines if DADC 1 or 2 is source of altitude data

216
Q

Where does the mode S code come from?

A

ICAO

217
Q

What is the break up of the Mode S code?

A

First 6-8 bits country of origin code

Remaining 18 bits unique S mode address

218
Q

What is the range of Mode S?

A

100nm at 10000 feet

200nm at 30000 feet

219
Q

What does the Air Traffic Control Radar Beacon System (ATCRBS) use to detect location of aircraft with respect to ground station?

A

PSR. The SSR then interogates AC for IDENT and ALT

220
Q

Is the LRRA pulse operated and what does it detect?

A

No, not a radar, is frequency modulated

Detects height AGL

221
Q

What happens if P1 = P2?

A

It will give an error. Means it has picked up suppression

222
Q

Where does airborn weather radar detect weather conditions?

A

Ahead of aircraft

223
Q

What does weather radar detect?

A

Weather that has precipitation in it (rain, thunderstorms etc)

224
Q

What does weather radar have difficulty in picking up?

A

Ice and hail, (dry precipitation)

225
Q

What does weather radar consist of?

A

Radome

Antenna

Wave guide

Radar RT

Plan Position Indicator (PPI)

226
Q

What is a radome?

A

Kevlar/fibre glass honey combe structure which protects radr antenna

227
Q

What does it mean when a radome is said to be transmissive?

A

Means how efficiently it permits RF energy to pass through without weakening the RF energy

228
Q

What are the two types of weather antennas?

A

Parabolic

Phased Array (flat plate)

229
Q

What do the two antennas both have?

A

Drive mechanism

230
Q

What do weather radar antennas do with RF energy?

A

Direct RF energy toward target (storm area)

231
Q

Where are the weather antennas and drive mechanism located?

A

Forward bulkhead

232
Q

What scan arc does the weather radar detect?

A

180 degrees

233
Q

What is the wave guide?

A

Hollow metal tube where the RF energy is transmitted by RT and passes through to the antenna

234
Q

What are the downfalls of the wave guide?

A

Can have moisture problems

235
Q

How do you overcome the moisture problems in the wave guide?

A

Application of cabin air pressure

236
Q

How much RF energy does the RTU produce/transmit?

A

9.333 GHz

237
Q

What is the range of the weather radar RTU?

A

Approx 300nm

238
Q

What does the weather RTU do?

A

Process and amplifies analog returning RF energy to produce digital data on the range, bearing and target info

239
Q

Where is the weather displayed after being detected?

A

on Plan Position Indicator (PPI) or EFIS

240
Q

Which is better, parabolic or phases array antenna?

A

Phased array antenna

241
Q

Why is the parabolic antenna worse than then phased array?

A

Parabolic produces side lobes

Parabolic uses more power (60 kw compared to 600 mW)

242
Q

Why is the phased array antenna more accurate?

A
  • Has slots over surface area
  • These slots ensure RF energy are efficiently radiated infront of the aircraft
  • Results in fewer side lobes and more RF energy to detect weather
243
Q

How much better is the phased array antenna than the parabolic antenna?

A

approx 50%

244
Q

What is the beam width of phased array antenna?

A

3 degrees

245
Q

What detrimental effect happen to RF energy when it detects a raindrop?

A

It reflects, refracts and is absorbed by the raindrop

246
Q

Fill out the below table with regards to weather radar detection

Colour Intensity Rainfall (inch/hour)

BLACK

GREEN

YELLOW

RED

MAGENTA (PURPLE)

A

1 <0.03

2 0.03-0.15

3 0.15-0.5

4,5,6 >0.5

BLANK TURBULENCE

247
Q

What does WX mode detect?

A

Detects rain storm along flight path

248
Q

What does WX/T detect?

A

Rain storm along path but adds turbulence area within storm as white. Range of 40nm

249
Q

With weather radars, what does TILT, do?

A

Adjusts radar angle for takeoff/cruise

250
Q

With weather radars, what does GAIN do?

A

Adjusts sensitivity of RT

251
Q

On the ground, what is the Maximum Permissible Exposure Level (MPEL) to weather radar

A

5-15 meters

240 degrees around radar

252
Q

Does the weather radar detect CAT? Why/why not?

A

No

Because CAT is usually free of precipitation

253
Q

What does forward looking weather radar do? What is it’s range

A

Predictive windshear (PWS)

Looks 5nm ahead, detects 3nm +/- 30 degrees

254
Q

Is FLWR reactive?

A

No

255
Q

Define severe wind shear

A

Wind change greater than 15 knots and/or verical change > 500 feet

256
Q

What aural warnings occur during take off for FLWR? At what distances? And when are these inhibited?

A

WINDSHEAR AHEAD

Warning 1.5 nm ahead

Inhibited at takeoff between 100kts and 50 feet

257
Q

At what height does FLWR operate automatically at?

A

2300 feet AGL

258
Q

What height are warnings and alerts generated at?

A

1500 feet below

259
Q

What does counter clockwise radar detect?

A

Windshear detection mode

260
Q

What does clockwise radar detect?

A

WX or MAP

261
Q

What are the aural warnings for FLWR during landing and when are they inhibited?

A

Go Around, Windshear

Inhibited below 50 feet

262
Q

How does the RF detect microburst?

A

Doppler effect, frequency shift.

Frequency increases (rain move towards)

Frequency decreases (rain moves further away)

Difference between the two

263
Q

What class is the minimum for FLWR and what is the % for trasnmissive efficiency?

A

Class B

87% to minimum 82%

264
Q

What is the priority of message?

A
  1. Stall warning
  2. PWS
  3. GPWS
  4. TCAS
265
Q

With the future multiscan radar, what range does it have?

A

320 nm

266
Q

Where is the VOR/LOC antenna?

A

Top of vertical stabiliser

267
Q

What does VOR/LOC antenna do?

A

Supplies RF signals received from VOR stations to the VHF NAV receiver

268
Q

What bonding does the VOR/LOC antenna have?

A

0.0001 Ohms

269
Q

What does the VHF Nav receiver do?

A

Processes valid VOR, LOC and G/S signals

270
Q

What systems does the VHF Nav receiver supply received data to?

A

ADI, HSI and RMI

271
Q

What frequency does ILS opperate?

A

108-112 MHz but at odd frequencies

  1. 10-119.95
    e. g.108.10, 108.15, 108.30 etc
272
Q

What frequency range does G/S operate at?

A

329.15 to 335.40 MHz

273
Q

What frequency does VOR operate at?

A

108.00 to 117.95 at even

so 108.20, 108.25, 108.40 etc

274
Q

What amplitutes varies, AM or FM?

A

AM

275
Q

What are the two ground transmitted signals?

A

Reference

Variable

276
Q

Describe the reference signal

A

AM by 9960Hz sub carrier signal

Subcarrier FM by +/- 480Hz

277
Q

Describe Variable Signal

A

Unmodulated RF, 360 degrees at 30 rev/s

278
Q

What are site error effects?

A

Anything in the way of the ground station

e.g. fences, buildings, terrain, fuel trucks etc

279
Q

What direction does VOR give?

A

Magnetic north

280
Q

How do you use VOR?

A
  1. Crew select VOR frequency
  2. Station IDENT by audio or morse code
  3. Bearing is displayed on HSI (360 radials)
  4. Select desired course by OBS knob (omni bearing selector)
281
Q

With VOR, what does one dot on the deviation bar (purple/magenta) mean?

A

5 degrees variation

282
Q

Intrument landing system (ILS), describe how it works

A
  1. LOC ground station transmits two signals either side of the runway
  2. Left signal at 90 Hz
  3. Right signal 150Hz

(LEFT or RIGHT audio)

283
Q

What does 1 and 2 dots means on LOC deviation bar?

A

1 dot = 1 degree deviation, 75uAmp of NAV Rx

2 dot = 2 degrees deviation, 150uAmp

284
Q

What does 1 and 2 dots on G/S deviation mean?

A
  1. 35 degrees deviation = 1 dot
  2. 7 degrees deviation = 2 dots
285
Q

How does the marker beacon work?

A
  1. When ac passes over outer mark, BLUE MKR comes up. 400Hz picked up
  2. When ac passes over middle marker, AMBER MKR comes up. 1300Hz picked up
  3. When ac passes over inner marker, WHITE MKR comes up. 3000Hz picked up
286
Q

What are some limitations of the VOR/ILS?

A
  • Limited to line of sight (200nm at 30000 ft)
  • depends on sensitivity of Nav receiver
  • Power of station
  • Terrain (site errors)
  • Altitude of aircraft
287
Q

If the aircraft is south of VOR, what comes up?

A

TO

288
Q

If the aircraft is north of VOR, what comes up?

A

FROM

289
Q

What sort of deviation is there on LOC and G/S?

A

LOC - lateral deviation

G/S vertical deviation

290
Q

What is GPWS?

A
  • Ground proximity warning system
  • Aural and visual warnings of potentially dangerous flight path relative to ground
291
Q

When is GPWS activated?

A

2500 feet and below

292
Q

What does GPWS require input from?

A

DADC and LRRA Systems

293
Q

Does VOR or ILS use GPWS?

A

ILS does

294
Q

What are the valid signals received by GPWS? What happens if it doesn’t receive them?

A

28vdc

INOP light appears

295
Q

What is the flap logic switch?

A

Cockpit switch located and guarded when landing with <25 degrees flaps

296
Q

At what voltage and hz does GPWS become functional?

A

115V AC and 400 Hz

297
Q

What are the priority of warnings?

A
  1. Whop whoop pull up (MODE 1 and 2)
  2. Terrain (Mode 2)
  3. Too Low Terrain (Mode 4)
  4. Too Low Gear (4a)
  5. Too Low Flaps (4b)
  6. Minimum (6)
  7. Sink Rate (1)
  8. Dont sink (3)
  9. Glide Slope (5)
298
Q

What is the main purpose of the 3 phase 115V ac electrical Fuel Boost pumps that are installed in aircaft fuel systems?

A

To provide pressurised fuel to the engines for operations

299
Q

By what two methods can the EGPWS/GPWS ‘Too Low Flaps’ warnings be silenced during aircafts landing phase, if the trailing edge flaps are NOT selected to the correct EGPWS/GPWS landing setting?

A
  1. Activate the inhibit switch
  2. Put the flaps down
300
Q

What are all the indications provided in the cockpit to the flight crew by the MKR Receiver when the aircraft passes over the outer, middle and inner makrer beacons?

A

You would hear an audible warning in the cabin that would increase in pitch at each marker. You would also see visual warnings in the cabin that would light different coloured light assemblies depending on what marker you are at

301
Q

What factors can affect HF operations?

A

Atmospheric conditions, ionospheric conditions, solar flares etc

302
Q

Name an electrical problem/fault that would cause the 10amp Tank 1 Aft Fuel Boost Pump circuit breaker to trip?

A
  • Short circuit
  • Electric pump motor seizure
303
Q

Breifly describe how the Fuel Boost Pump operates.

A
  1. The circuit is connected to the 28 volt DC bus 1 because it is essential
  2. Tank 1 aft boost pump is connect to a relay
  3. When the switch the aft boost pump relay (P6) is activated which close A1/A2, B1/B2, C1/C2 switches in the 3 phase circuit.
  4. 3 phase circuit is powered via the 115 volt AC XFR Bus 1 and provides power to the aft boost pump which becomes active
  5. Aft boost pump relay has now completed its circuit
304
Q

What is the benefit of having three phase 115 Vac power sourced from the aircrafts generator as opposed to having single phase only?

A
  • More efficient
  • More reliable
  • Lighter
305
Q

What affects does elimination of the CSD/IDG have on the ac power that is generated and what is the benefit?

A
  • Wild generated power signal fluxation (frequency wild) with engine RPM
  • More reliable output due to no moving parts
306
Q

What are the benefits by using side bands (USB/LSB) when transmitting on HF?

A
  • More efficient
  • require less energy
  • produce clearer audio signals
  • signal goes further
307
Q

With a forward looking weather radar operating below 2300 feet, when will the radar antenna be operating in the crew selected mode and when will it be operating in the windshear detection mode?

A

Crew selection mode = clockwise

Windshear detection mode = counter clockwise

308
Q

What are two components installed in the AC where ATC transponder gets altitude info?

A
  1. DADC
  2. encoding altimeters
309
Q

Aircraft equipped with TCAS does not have a rotating SSR antenna like an ATC ground station, yet it can be described as a flying ground station. Why?

A
  • 4 direction antenna that pulses intermittently at specific frequency so as to emulate the rotating effect of ground station which outputs interogation signals to other aircraft
310
Q

Excludding LRRA which of the following DO NOT depend on input from the LRRA for their normal ops?

EGPWS

EWIS

FLWR

FFRAT

REU

LRRA

A

EWIS and REU

311
Q

What method would you use to identify wires?

A

UV etching

312
Q

What method was used for identifying wires but isn’t any more?

A

Hot stamping

313
Q

Individual cells of the Ni-Cd battery are connected in paralle, series or both?

A

Series

314
Q

Which of the three TRUs on a 737 supplies the 28V dc battery bus under normal operating conditions?

A

TRU#3

315
Q

A landing gear repair is taking place requiring the aircraft to be jacked so the wheels are off the ground and electrical power remaining on. What action must the maintenance crew do prior to jacking to ensure data in the DFDR tape is not erased?

A

Pull the CB from the FDR or ground sense logic circuit

316
Q

The flight crew has removed the boom microphone headset originally tested and certified for the CVR system by Boeing and connect their own personal Boom-Mic into the audio system. What impact could this have on the CVR?

A

They may not be compliable and not record any voice/audio

317
Q

When does TADS become activated?

A

It is selected by crew however becomes automatically active if terrain becomes a threat

318
Q

Which is predictive and which is reactive out of EGPWS and PWS?

A

EGPWS = reactive

PWS = Predictive

319
Q

What happens when you are 60 seconds away from terrain?

A

Caution terrain

320
Q

What does TCAS use?

A
  • Mode S transponder
  • ATCRBS
321
Q

At what frequency does TCAS processor send and receive info?

A

Send 1030MHz

Receive 1090MHz

322
Q

What is TA and RA?

A

TA = traffic advisory (another aircraft is in the vicinity)

RA = Resolution advisory (potential conflict exists)

323
Q

With TCAS, if you select N in the ABV/N/BLW switch, what happens?

A

Detects 1700 feet above to 1700 feet below

324
Q

With TCAS, if you select ABV in the ABV/N/BLW switch, what happens?

A

Detects 7000 feet above to 2700 feet below

325
Q

With TCAS, if you select BLW in the ABV/N/BLW switch, what happens?

A

Detects 1700 feet above to 7000 feet below

326
Q

With TCAS, what does a red square, down arrow and minus 03 represent?

A
  • Red square = RA
  • Down arrow = aircraft descending > 500 ft per min
    • 03 = 300 feet below
327
Q

What does a yellow circle with up arrow +05 represent with TCAS?

A
  • Yellow circle = TA
  • Up arrow = climbing > 500 feet per min
    • 05= 500 feet above
328
Q

What does an open diamond and solid diamond represent?

A

Open diamond = other traffic, no threat

Solid diamond = proximate ac that won’t penetrate collision boundary

329
Q

What do the 12 little white dots in TCAS represent?

A

2 nm radius around AC

330
Q

What are some of the main aural warnings for TCAS and which are TA and RA?

A

Climb climb (RA)

Descend descend (RA)

Traffic traffic (TA)

Clear of conflict

331
Q

What is the approx range for TCAS?

A

40nm

332
Q

How far away approx are RA threats?

A

20-25s

333
Q

How far away are TA threats?

A

40-45 seconds

334
Q

What information does a 737-300 aircraft’s VHF Navigation Receiver provide for
the GPWS?

A

ILS

335
Q

List three EGPWS “enhancements” that are pin selectable at the rack connector of
the EGPW Computer (EGPWC)

A
  1. TADS
  2. Windshear
  3. ALT Callout
336
Q

The aircraft’s Navigation Receiver detects and compares the angle between the
received VOR signal and the course selected by the crew using the Omni Bearing
Selector control (knob). What indications on flight instruments, does the difference
between these two angles provide to the crew regarding where the aircraft is with
respect to the VOR radial?

A

45 degrees

337
Q

Re-coupling of the 737-300 Generator Drive shaft to the engine is accomplished?

A

On the ground

338
Q

What does EWIS stand for?

A

Electrical Wiring Interconnection System

339
Q

What does AWG stand for?

A

Avionics Working Group

340
Q

What instrument is required by ground maintenance personnel to check that the ground connection for such circuits meet Maintenance Manual requirements?

A

Bonding measure

341
Q
A