15.14 Flashcards
(169 cards)
1
Q
Where is the highest temperature in an engine?
A
Directly behind the combustion chamber at the High pressure turbine (TIT)
2
Q
Where is EGT measured?
A
Between the high and low pressure turbine/ directly behind the low pressure turbine
3
Q
What are the temperatures (including the EGT relative too)
A
Gasses entering the first stage turbine inlet vanes
4
Q
What is used to measure the temperature, and where are they placed?
A
Thermocouples near the turbine exit by the exhaust
5
Q
What do the EGT’s show?
A
The average temperature from the thermocouples
6
Q
How are EGT’s sealed?
A
Hermetically
7
Q
TIT indicating system shows information how?
A
A visual indication on the instrument panel
8
Q
Because numerous thermocouples are used to find TIT, what must you do?
A
Find an average
9
Q
Dual thermocouples contain two electrical junctions for what two purposes?
A
One to send signals to the flight deck and the other to provide signals to control and monitoring systems
10
Q
What happens when the TIT reaches a predetermined limit?
A
An over temperature warning light in the indicator illuminates
11
Q
What do digital indicators not use?
A
Resistance-type or servo-driven thermocouples
12
Q
What are the three groups engine indications can be split into?
A
Performance Indications
System indications
Engine trend monitoring
13
Q
What are performance indications also known as? And what are they for?
A
Primary indicators and they are used to monitor the performance and limits of the engine.
14
Q
What can you do with performance indications?
A
Set thrust for different flight phases
15
Q
What are system indications also known as?
A
Secondary indications
16
Q
What are system indications used for?
A
Monitor the operation (such as fuel and oil) and detect malfunctions quickly
17
Q
What is engine trend monitoring?
A
It is done on the ground to detect engine problems early.
18
Q
What does engine trend monitoring use?
A
ACMS (Aircraft condition monitoring system)
19
Q
Which of the three indications do not show up on the flight deck?
A
Engine trend monitor
20
Q
Where are engine indications shown in the flight deck?
A
ECAM at the top
21
Q
Engine performance indicators are used to do what?
A
Monitor and set engine thrust
22
Q
What are the two values used to measure thrust because you can’t measure it directly?
A
EPR (Engine pressure ratio)
The rotational speed of fan N1
23
Q
What is another performance indicator ?
A
Engine rotor speed for each rotor system (N1 N2 N3)
24
Q
What are two examples of engine performance indicators?
A
Exhaust gas temperature and fuel flow indications
25
Where does the computer send the data to?
The indicators or display system. (Use it to control the engine)
26
What are engine system indications used to monitor?
Correct operation
27
What does the engine vibration indication show?
Imbalances that occurs in rotating parts of the engine
28
What do engine trend monitoring systems prevent?
Engine problems during flight/engine reductions
29
The engine data is analysed by a computer system that does what?
Find any parameters that indicate a trend towards a limit
(thermo-dynamic, mechanic
-dynamic, oil consumption)
30
What does thermodynamic show?
Checks the pressure and temperature
31
What does mechanic dynamic show?
Failures in the rotor system
32
What does the oil consumption analysis generate?
An alert when the oil consumption is exceeded
33
How are EPR indications shown?
Analogue or digital
34
The EPR function has the same command as what?
The N1 command
35
What does an AMBER or RED line show?
The EPR for maximum thrust
36
What does the blue circle show on an EPR display?
The actual throttle position
37
What is Flexible Take Off, 'FLEX'?
Standard take off thrust setting used on Airbus
38
When is TOGA used?
On a contaminated(wet/icy) runway or if performance changes (short runway)
39
What Is TOGA?
Full thrust
40
What do FLUX take-off settings use?
why?
An assumed temperature thrust reduction
To prolong engine life
41
What term do Boeing use?
Assumed temperature derate
42
Why is the oil supply system monitored?
To guard against engine failure from inadequate lubrication and cooling?
43
What does the oil pressure indicator usually show in regards to the engine oil?
The engine oil pump discharge pressure
44
What are the 2 types of oil pressure transmitters?
Borden tube
Strain gauge
45
What shape is the Borden tube?
C-shaped or helical with an oval cross section
46
When the pressure enters the tube what happens to the cross-section of the Borden tube?
It becomes circular extending the helix
47
What does the extension of the helix cause?
Indicator needle to deflect which is proportional to the pressure exerted
48
What can a Borden tube have to provide an electrical representation of the pressure?
A potentiometer
49
What does a string gauge measure?
Mechanical strainer deflation
50
What principle do strain gauges work off of?
When an object undergoes stain the resistance changes proportionally
51
What does a strain gauge look like?
Small and rectangular, made of metallic foil for electrical properties
52
What is a strain gauge designed in a specific pattern to maximise?
Sensitivity to strain
53
What is the most common arrangement for a strain gauge?
Wheatstone bridge configuration
54
What is a Wheatstone bridge configuration?
Grid like pattern with several active arms and a central section when the strain is applied
55
What do the active arms do?
Detect the strain, and change their resistance accordingly
56
What happens when strain is applied to a strain gauge?
The object deforms and its length changes
57
What causes an alter in the electrical resistance of the strain gauge?
The change in active arms length
58
What happens when no strain is applied to the object?
The Wheatstone bridge is balanced, meaning the voltage is 0
59
When the bridge becomes unbalanced therefore creating a voltage difference, what initially occurred?
When strain is applied to the object
60
What must you do the output voltage of the Wheatstone bridge?
You must filter it
61
What is the low oil pressure switch used for?
Initiate a low oil pressure warning
62
Where is the low pressure switch connected to?
The oil supply line and oil tank vent line
63
What happens to the low oil pressure switch when oil pressure decreases below the limit?
It closes, a signal is sent to the flight warning computer and a warning message appears in the flight deck
64
What is an oil Inlet temperature indicator used to do?
Indicate the temperature of the oil as it enters the oil pressure pump
65
What is the primary component responsible for measuring the oil temperature?
The oil temperature sensor which is designed to respond to changes in temperate and convert the information into electrical signals
66
What is the most common type of oil temperature sensor?
The resistance temperature detector (RTD) or thermocouple
67
What is an RTD made up of?
A temperature sensitive resistor
68
What happens when the oil temperature exceeds operational limits?
The pilots get an over temperature warning
69
What happens during an over temperature warning?
Can be visual and audible
70
Where is the Low pressure sensor positioned?
After the outlet for the low pressure filter
71
Where can low fuel pressure originate from?
Cavitation caused by high fuel pump demand
72
What type of sensor is located on the fuel filter?
Differential pressure sensor
73
What do differential pressure sensors give warning of?
Impending blockage and cavitation
74
How is a warning of low pressure fuel displayed?
As a warning lamp or EICAS message
75
What type of pressure gauge do light recoporricating engines use?
Bourdan tube
76
What is the pressure gauge connected to?
The fuel inlet of the fuel metreing device
77
What do more complicated aircraft have located at the fuel inlet of the fuel metering device?
A sensor that sends electrical signals to flight deck
78
What does the gauge indicate when the auxiliary pump is switched off?
The pressure created by the engine driven pump
79
What type of engine may use a differential fuel pressure gauge?
Complex and large aircraft
80
What happens to the contacts of the switch when the fuel pressure is insufficient?
They close which sends a current flow to the annunciator or waning light in the flight deck
81
Where are low pressure warning switches located?
At the outlet of each fuel boost pump
82
Where is the annunciator for each switch positioned?
Adjacent to the boost pump on/off switch
83
Where is ice likely to form due to low fuel temperature?
Filters
Fuel system
84
What type of aircraft use a resistance type electric fuel temperature sender?
High performance
85
What can low fuel temperature be corrected with?
Fuel heater
86
What does viscosity differences at varying fuel temperatures affect?
Fuel flow sensing accuracy
87
How can you correct viscosity differences affecting fuel flow sensing accuracy?
Thought the use of computers
88
The fuel flow indicating system provides what 2 different indications?
Actual fuel flow to the engines and the fuel used since the engines were started
89
Why does each flow indicator show identical fuel flow?
Because the engines have the same power setting
90
What does the fuel flow transmitter measure?
The mass flow of the fuel between the fuel control unit and the fuel nozzles
91
What do all fuel flow transmitter types measure?
The force applied by the mass of fuel
92
What are the 2 types of flow meters?
Synchronous and motorless
93
What is measured in synchronous mass flow?
The deflection angle (a turbine is turned against the spring)
94
In synchronous mass flow to get the force, what. just you do to the fuel?
You must accelerate it
95
How do you accelerate the fuel?
By an impeller that is driven by an electric motor continuously
96
What do motorless mass flow not need?
An electric motor with a power supply
97
What do motorless mass flow use to accelerate the fuel?
The fuel itsel
98
What does the fuel flow turn in a motorless mass flow?
A turbine
99
What does the rotating turbine drive?
The drum and impeller coupled by a spring
100
When the impeller magnet is delayed, what else is also delayed?
Impeller coils
101
What does the FADEC calculate in motorless mass flow?
The time between the 2 pulses, which is proportional to the mass flow
102
What does interrogation of the fuel flow value give?
The required fuel used
103
What is N1 for?
Low-pressure rotor
104
What is N2 for?
High-pressure rotor
105
When is a N3 indication used?
When there is 3 rotors
106
What are engine rotor speeds expressed as?
A percentage of a 100% design speed
107
What are the 2 types of sensors used to measure rotor speed?
Tachometer
Variable reluctance type
108
What is another name for a variable reluctance type sensor?
A magnetic reluctance type sensor or magnetic pickup
109
Where is a tachometer generator type usually located?
On the gearbox
110
How does a variable reluctance sensor work?
Magnetic flux, between a magnet and a ferromagnetic target (magnetic reluctance)
111
Where is the speed probe positioned?
On the compressor casing with a phonic wheel or fan blade
112
what changes in the speed probe when the spool rotates?
Probe or sensor head is altered
113
What causes magnetic flux to vary when passing through the sensor?
Magnetic reluctance
114
What is directly proportional to the rate of change ofd magnetic flux?
Induced voltage
115
What must happen to the induced voltage before it can be an output?
It must be amplified
116
What does the tachometer rotating magnetic field generate?
A three phase AC voltage
116
117
What is the permanent magnet in a tachometer driven by?
The gearbox
118
Because the permanent magnet in the Tachometer is driven by the engine gearbox, what is the speed directly proportional to?
N2
119
What does the Tachometer send the 3 phase AC voltage to?
FADEC which is used to dictate super
120
What does the Tachometer send the 3 phase AC voltage to?
FADEC which is used to dictate super
121
Why is the Tachometer also called the dedicated generator or control alternator?
Because it also supplies electrical power to the generator
122
The speed probe or Tachometer can also send a warning to the flight deck that tells the pilot what two things?
That the engine is turning
And what direction it is turning in
123
The speed probe or Tachometer can also send a warning to the flight deck that tells the pilot what two things?
That the engine is turning
And what direction it is turning in
124
When is it important for the pilot to know the engine is spinning and its direction?
During start up as it is used to tell the Pilot when to open the HP fuel cock
125
What value do all three indications show?
N1
126
What does the red line on the speed indicator show?
Over speed
127
What occurs if the rotor speed N1 goes over the over speed red line?
It is recorded via the engine trend monitoring
128
What occurs if the rotor speed N1 goes over the over speed red line?
It is recorded via the engine trend monitoring
129
What does vibration show?
An imbalance in the rotor
130
What do the vibration units vary to?
0-6
131
What is another name for the computer that collects and filters engine vibration data?
The EVMU (Engine vibration monitoring unit)
132
The vibration sensors are accelerometers that measure what type of acceleration?
Radial
133
Where are the two accelerometers sensors placed in the engine?
One on the N1 compressor
The second in the turbine area
134
What are the two types of accelerometers used in an engine to measure vibration?
Piezoelectric-crystal type
Electromagnetic
135
What is the electromagnetic sensor?
Permanent magnetic held in place by two springs. When vibration occurs, the coil moves up and down
136
What is the electromagnetic sensor?
Permanent magnetic held in place by two springs. When vibration occurs, the coil moves up and down
137
How does a piezoelectric crystal work?
You apply a force to the crystal which pushes it against the base plate
138
What is the vibration indication controlled by?
Engine vibration monitoring unit
139
What is shown on the rotor identifier if the N1 or N2 rotor speed fails?
Broadband vibration
140
What does the vibration have to be more than for it to automatically show up on the secondary display?
4
141
What does the vibration have to be more than for it to automatically show up on the secondary display?
4
142
When the engine is shutdown, what will the vibration and performance page show?
0.00
143
What performs a balance calculation that corrects the engine high vibration?
The engine balancing system
144
What performs a balance calculation that corrects the engine high vibration?
The engine balancing system
145
What does the solution of the engine balancing system identify?
The balance weights that are required to be removed and replaced on the LPT blades
146
What does the solution of the engine balancing system identify?
The balance weights that are required to be removed and replaced on the LPT blades or engine spinner
147
Are torque meters electric or hydraulic?
Both
148
What do torquemeters measure?
Torque being delivered to the propellor or rotor
149
How many concentric shafts do torque meters comprise of?
2
150
How many concentric shafts do torque meters comprise of?
2
151
What does the inner shaft connect?
The drive from the engine to the gear box
152
What does the outer shaft connect?
The engine output only
153
What is on both shafts? And what does this induce?
Toothed gears and permanent magnets
EMF forces
154
When happens to the output shaft when the torque is applied and increase?
Twists
155
What operates the torque meters?
Engine oil pressure metered through a valve
156
What is the most importantly thing a torque meter does?
Set power settings
157
What is the most importantly thing a torque meter does?
Set power settings
158
What is the Power assurance test?
To check the engine can go from idle to a given engine power ratio within a specific time and back to idle in a specific time
159
What must you ensure when doing a power assurance check?
Engine must be positioned in run up enclosure/position
Facing into the wind
Chocks plages
160
What must you ensure when doing a power assurance check?
Engine must be positioned in run up enclosure/position
Facing into the wind
Chocks plages
161
During a power assurance check, how long must you hold the engines at idle for?
5 minutes
162
During a power assurance check, how long must you hold the engines at idle for?
5 minutes
163
What must you identify before running a power assurance check?
EPR for that day
164
What must be switched off to ensure the engines can accelerate correctly?
Anti ice and engine bleed valve
165
What must be switched off to ensure the engines can accelerate correctly?
Anti ice and engine bleed valve
166
How long must it take you to reach EPR, hold it there for and then decrease back to idle?
30 seconds
167
After engine operation above 70% N1 how long must you operate the engine at idle for?
10 minutes to decrease the engine temp safely shut down the engine
168
What are the units used to measure fuel?
Kg or tonnes
