Auxiliary MIDTERMS Flashcards
(126 cards)
1
Q
deals with compressed or pressurized gas as a source of power.
A
Pneumatic
2
Q
Normally the gas used in pneumatics is
A
air
3
Q
On aircraft pneumatic energy is used for
A
- engine starting
- cabin pressurization and air conditioning
- wing anti-icing water reservoir pressurization
- hydraulic reservoir pressurization on some aircraft
4
Q
On all jet aircraft there is?
A
a very good air source available
5
Q
provides enough air for combustion purposes and also for the pneumatic system.
A
engine compressor
6
Q
You can see that the compressed air is bled from the engines, so therefore it is called
A
Engine Bleed Air or EBA
7
Q
used to supply the pneumatic system
A
auxiliary power unit (APU)
8
Q
The only built-in air pressure sources are
A
engines and the APU
9
Q
If both the APU and engines are not running we can assume that?
A
aircraft is on the ground; if it isn’t we have a very serious problem
10
Q
If the aircraft is on ground
A
the pneumatic system can be supplied with external air
11
Q
third air source can be delivered via?
A
connectors, the High Pressure Ground Connectors
12
Q
main source of air for the pneumatic system
A
engines
13
Q
first of all the engines produce?
A
thrust to fly the aircraft
14
Q
If thrust is increased, pressure?
A
pressure increases as well
15
Q
Thrust changes generate?
A
varying amounts of air pressure
16
Q
maintain a constant level of pressure and regulate the engine bleed air supply at high engine speeds
A
pressure regulator
17
Q
pressure regulator is known as?
A
bleed valve
18
Q
At high engine speed the engine bleed air pressure is?
A
regulated
19
Q
In a situation when the engine thrust is at idle, __
A
a second engine bleed port is used
20
Q
The temperature in the pneumatic system must?
A
not exceed acceptable values
21
Q
if engine thrust increases, temperature?
A
increases and vice versa
22
Q
used to cool the engine bleed air temperature
A
built-in precooler
23
Q
is taken from the engine fan duct
A
cooling air
24
Q
The cooling air is simply?
A
fan air
25
The cooling effect depends on?
mass and temperature of fan air
26
in order to vary the cooling effect,
the mass of fan air must also be varied
27
used to allow more or less fan air to pass the precooler
fan air valve
28
The pneumatic air is distributed via?
ducts
29
Depending on the location of the air ducts they are known as the?
pylon duct, the left and right wing ducts, the APU duct and the crossover duct or cross-bleed manifold
30
usually located in the fuselage and connects the left and right wing pneumatic ducts
cross-bleed manifold
31
found to isolate the left from the right wing pneumatic duct
cross-bleed valve
32
control of the pneumatic system achieved either?
manually via the pneumatic control panel in the cockpit or automatically by the pneumatic controller
33
computer with specified tasks
pneumatic controller
34
how many pneumatic controller/s for each engine bleed air system?
one
35
role of the pneumatic controller
monitor pressure and temperature, to register leaks and to monitor the operation of the pneumatic components
36
aircraft fly at very high altitudes mainly for?
economic reasons
37
flying at very high altitudes mainly for economic reasons presents some problems because?
humans are not able to live in this environment without help
38
The air pressure is so low that there is?
not sufficient oxygen for human survival
39
crew and passengers must be protected against?
freezing and death
40
air conditioning system makes sure there is?
correct pressure in the cabin to support life and it also ventilates the cabin to keep the temperature in a comfortable range
41
The air conditioning system supplies pressurization to?
the whole passenger compartment, the cockpit, all the cargo compartments and the avionic compartment
42
There are areas in the fuselage that are not pressurized and these are separated by?
pressure bulkhead
43
Areas that are not pressurized
landing gear bays, the radome and the tail cone
44
The air conditioning system must make sure of 5 physical charactistics. It must make sure that the air is:
- fresh,
- clean,
- at a comfortable temperature,
- at the correct humidity and
- at the correct pressure
45
Air Conditioning Functions
- The air must be clean. It must be free of all harmful or hazardous gases or vapors.
- Air filters are fitted to keep the air clean and at high altitudes for extra protection ozone converters are built in.
- The temperature must be in a comfortable range. Most aircraft permit temperature regulation in the range of about 18°Celcius to 30° Celcius, corresponding to 64° Fahrenheit to 86° Fahrenheit
46
Most aircraft permit temperature regulation in the range of?
about 18°C to 30° C, corresponding to 64° F to 86° F
47
a big problem
humidity of the air on board an aircraft
48
depends on air temperature
humidity
49
what holds more water? warm or cold?
warm air holds more water than cold
50
Near the ground there is a lot of?
humidity in the ambient air
51
The temperature regulation cycle causes the temperature to?
decrease dramatically which results in water droplets
52
To prevent the freezing of parts and valves and also to prevent fog and water droplets in the cabin,
water is separated from air
53
air supply comes from
pneumatic system
54
air supply comes fromair conditioning system starts
pack valve
55
air is cooled by
2 or more identical packs
56
air conditioning system mixes
cooled air with hot air to give the desired temperature in the conditioned compartments
57
air conditioning system also supplies the necessary?
cooling of panels, batteries and electronic racks by ventilating them with air
58
the conditioned air is distributed to the?
compartments
59
The cabin and flight compartment are pressurized to?
supply a pressure corresponding to all flight altitudes
60
pressure is regulated by the?
outflow valve
61
air used by the airconditioning system is?
bleed air from the pneumatic system
62
pneumatic air is flow regulated by?
pack valves
63
This pneumatic air is flow regulated by the pack valves, which are therefore also called?
flow control valves
64
From the pack valves the air goes to the?
packs
65
The air conditioning packs cool the pneumatic air to a?
basic temperature
66
The cooled air then flows to a?
mixing unit
67
The mixing unit mixes the
cold air from the packs with recirculated cabin air
68
you get the same airflow in the cabin with a?
lower pack airflow
69
The temperature of the air that leaves the mixing unit is finally adjusted by a certain amount of hot air that comes from?
upstream of the packs
70
hot air is also called?
trim air
71
You can also supply air to the mixing unit from an?
external airconditioning unit on the ground
72
You connect this unit to a _______ if you don't want to use the packs on ground
low pressure ground connector
73
The temperature of the air that is now delivered to the
cabin zones
74
2 steps of how temperature of the air is regulated
Pack controllers regulate the temperature of the cold air that leaves the pack
zone controller regulates the amount of trim air that is mixed with the cold air
75
regulates the temperature by comparing the actual cabin temperature with a selected zone temperature set by the flight crew
zone controller
76
Each cabin zone has its own
control loop
77
The zone controller also defines the
temperature of the cool air and sends this information to the pack controller
78
The air conditioning packs, the valves and the mixing unit are located in the?
center wing box area
79
The air conditioning controls are located on the
overhead panel in the cockpit. You will also find the indication displays in the cockpit.
80
pack and zone controllers are located in the
avionics compartment
81
low pressure ground connectors are located on the
lower fuselage, accessible by a door
82
basic idea of cooling
heat is a form of energy it cannot be made or destroyed, it can only be transformed
83
Heat can only flow from
an object to a cooler object
84
3 types of cooling device used on aircraft
- heat exchanger
- vapor-cycle machine
- air-cycle machine
85
are very effective, but they do not have sufficient power to cool all of the cabin air, especially on the ground
heat exchangers
86
are used in aircraft when engine bleed air is not available
vapor-cycle machines
87
The cooling principle is basically the same as in a refrigerator
An expansion valve expands a special pressurized cooling fluid by a specific amount.
88
The special cooling fluid expands which results in the fluid becoming
colder
89
This cold fluid flows through an
evaporator
90
This cold fluid flows through an evaporator, which is a special heat exchanger and is heated by the cabin air which flows across the evaporator. So the result is that the?
cabin air temperature decreases
91
The cooling fluid, which is now heated by the cabin air, changes its state from a
fluid to gas
92
special cooling fluid, which is now a gas, is?
compressed in the compressor
93
This compression gives the gas a?
higher temperature
94
This hot gas flows through ____ which is a special heat exchanger
condensor
95
In the condenser the special cooling gas is cooled down by
ambient air
96
You can find vapor cycle machines on
small aircraft with propellers, on aircraft without an APU and on older aircraft
97
use bleed air which comes from the pneumatic system
air-cycle machines
98
The hot, pressurized air flows into a compressor, which
increases the pressure and the temperature
99
The heat exchanger receives
hot air from the compressor.
100
After the air has been through the heat exchanger, it flows into a
turbine
101
air in turbine which is now warm, but still highly pressurized, ____?
expands and cools
102
This cold air then goes to the
cabin
103
driven by the turbine
Air-cycle machines
104
The turbine and the compressor are mounted on
1 shaft
105
cool hot bleed air to a value given by the pack controller.
cooling pack
106
The cooling pack has:
- a pack valve, which is the tap of the pack,
- an ozone converter which is located upstream of the pack valve and
- a heat exchanger which usually has 2 units, the primary and secondary or main heat exchanger
107
air-cycle machine and a bypass valve also called
temperature control valve
108
The cooling pack also has a
ram air system
109
ram air system has
ram air ducts with ram air inlet and exit doors and a fan
110
sense the temperature in the pack and these permit the pack to be controlled and monitored
cooling pack sensors
111
eliminates icing conditions in the water separator
anti-ice valve or sometimes and anti-ice function
112
The cooling pack has a pack check valve which is located
downstream of the water separator
113
pack check valve prevents
backflow into the pack
114
controls pack operation
pack controller
115
Each pack has a
pack controller
116
primary components of air cycle machine
compressor, the turbine and the fan
117
Hot pneumatic air flows from ___ to the ___ where it is cooled down
pack valve, primary heat exchanger
118
Air then goes to the compressor and is compressed increasing its
pressure and temperature
119
where the temperature is decreased, but the pressure stays the same
secondary or main heat exchanger
120
The air then goes to the ____ expands, causing the pressure and temperature to decrease. The air then goes to the cabin
turbine
121
The cold air from the packs goes into the
A mixing chamber is a direct-contact heat exchanger.
122
mixing chamber unit also called the
Plenum chamber
123
large chamber, like a big duct which has ports for incoming air and outgoing air.
Mixing unit
124
The mixing unit lets the
cold air from the packs mix with discharged cabin air
125
The system supports the airflow from the packs, so that the packs do not have to run on high airflow each time.
recirculation system
126
suck discharged cabin air from the underfloor area, clean it with filters and feed it back into the mixing unit
recirculation fans
