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Mod 11: Systems > 11.4 Contd - Pressurisation > Flashcards

11.4 Contd - Pressurisation Flashcards

1
Q

How is an aircraft pressurised?

A

Constant flow of air from the air the aircraft packs and the pressure is controlled by modulating the outflow valve.

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2
Q

What is a negative pressure relief valve?

A

Prevents higher pressure building up outside fuselage than the inside pressure.

Negative Pressure relief valve / vacuum relief valve allows pressure outside aircraft into the cabin.

This negative pressure differential mostly occurs during descents

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3
Q

What is cabin differential pressure?

A

Cabin differential pressure is the ratio between inside and outside air pressures and is a measure of the internal stress on the fuselage skin.

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4
Q

Describe a cabin altitude profile for an aircraft taking off from sea level and landing at 500 ft?

A

Cabin vertical speed - 500 ft/min climb rate

Cruise - max cabin altitude 8,000 ft

Cabin vertical speed - 300 ft/min descent rate

Adjust barometer from take off to landing (sea level to 500ft for landing)

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5
Q

How is cabin pressure controlled?

A

Varying the amount of air allowed to leave the cabin through the controller operated outflow valve controls the cabin pressure

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6
Q

How are the outflow valves operated?

A

AC-motor is used for automatic mode and controlled from the cabin pressure controller.

DC motor is used for manual mode and controlled by switch in the cockpit

AC- automatic control

DC - manual control

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7
Q

What is normally the position of the outflow valve after landing

A

Fully Open

(Just before landing will be fully open so airframe doesn’t have to take landing load and pressure load at same time)

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8
Q

What 3 indicators will the flight crew have for pressurisation system?

A

Cabin altitude indicator

Cabin VSI (Vertical Speed indicator)

Differential Pressure indicator

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9
Q

Which one of the pressure indication displays senses outside ambient pressure?

A

Cabin Differential Pressure Indicator

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10
Q

What warnings are there for the cabin pressurisation system (and at what altitudes)?

A

Press Relief warning light (is on as long as a pressure relief valve is open)

Rate Limit warning light ( Comes on if excessive vertical speed rate is detected >500 PSI ascent or >300 PSI descent)

A cabin altitude warning switch senses cabin pressure and initiates an intermittent warning sound in the cockpit if the cabin altitude exceeds 10’000 ft. The warning sound can be stopped by pressing the horn cutout P/B on the indication panel.

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11
Q
A

b) the structural strength of the aircraft cabin

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12
Q
A

b) cabin is not pressurised

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13
Q
A

b) the outflow valve must be closed

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14
Q
A

a) to regulate the cabin pressure

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15
Q

What are the 3 primary functions of a cabin pressurisation system?

A
  1. Maintain a cabin pressure altitude of 8,000 ft at the maximum designed cruising altitude
  2. Prevent rapid changes to cabin altitude, max climb rate 500 ft/min , max descent rate 300 ft/min
  3. Pressurisation system should permit a reasonably fast exchange of air from inside to outside the cabin to eliminate odours and to remove stale air.
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16
Q

The amount of air pumped into the cabin is in excess of that needed.

Varying the amount of air allowed to leave the cabin through the controller operated ____ ____ controls the cabin pressure

A

Outflow valve

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17
Q

The pressurisation system provides the pressure differential between the ____ and ____

A

Cabin and ambient

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18
Q

What should the Cabin/Ambient differential pressure be approximately

A

8 PSI

(7.29 PSI exact)

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19
Q

Pressure control systems consist of:

1.

2.

3.

4.

5.

A
  1. Outflow valves
  2. Pressure controller
  3. control panel
  4. Pressure Relief valves
  5. Negative Relief valves
  6. Monitoring indicators
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20
Q

A ____ ____ ____ is used to start pressurisation after lift-off and fully open the valves after landing.

A

Ground relay input

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21
Q

Pressurised air comes from the same air as the ___ ____ ____

A

Air conditioning system (Pack)

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22
Q

Cabin pressure is controlled by _______ ____

A

Outflow Valve(s)

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23
Q

The cabin Outflow valve(s) is ______

It is never fully open or fully closed, it is always somewhere in between

A

modulating

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24
Q

The Outflow valve(s) is controlled by two motors, explain:

A

AC motor which is controlled by the Cabin Pressure Controller (CPC) and is automatic (Auto mode)

DC motor which is controlled by a switch in the cockpit (manual mode)

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25
Name the 3 pressurisation indicators/gauges that are in the cockpit?
* Cabin Altitutude (Max 8,000 ft) * Vertical Cabin speed indicator (ascent 500 ft/min max, descent 300 ft/min max) * Differential Pressure Indicator
26
Pressing the aircraft 'Ditching' P/B will cause ....
All valves to close
27
When is the purpose of a Positive Pressure Relief Valve?
Opens when cabin pressure is higher in comparison to ambient pressure
28
What is the purpose of a Negative Pressure Relief Valve?
Allows pressure outside aircraft into cabin i.e Opens when ambient pressure is greater than cabin pressure (usually occurs if descent is too great)
29
What does a Safety Relief valve consist of?
Positive and Negative Pressure Relief valves
30
What is cabin altitude?
Cabin altitude is the height (in ft) that the cabin would be at in terms of pressure
31
What is the result of closing the Outflow valve?
Closing the outflow valve reduces air leaving the cabin causing the pressure to increase and cabin altitude to decrease
32
What is the result of opening the outflow valve?
Opening the outflow valve will decrease the cabin pressure causing the cabin altitude to climb
33
What is the purpose of blow out panels?
Blow out panels are fitted in the floor between passenger and cargo compartments in order to prevent excessive differences in pressure occurring between these areas.
34
What is the maximum cabin altitude allowed?
8,000 ft
35
What is the Maximum differential pressure allowed?
7.29 PSI | (8 - 9 psi)
36
Positive Pressure Relief valves prevent excessive ____ \_\_\_\_\_ \_\_\_\_
Positive Differential Pressure
37
Negative Pressure Relief Valve prevents _____ \_\_\_\_ \_\_\_
Negative Differential Pressure
38
What is the purpose of the Dump Valve?
The Dump Valve is used to completely depressurise the aircraft
39
What does the Ditching control P/B do?
The Ditching control PushButton closes all outflow valves prior to landing on water
40
Where are Blow Out panels fitted?
Blow Out panels are fitted in the floor between the passenger and cargo compartments
41
There will be an aural or visual warning when the cabin altitude ...
Exceeds 10,000 ft
42
In a turbine-engine powered aircraft the air for pressurisation comes from the _______ section of the engine
compressor
43
The air used for pressurising a turbine-engine powered aircraft is called __________ air
compressor bleed
44
The cabin altitude is the same as the flight altitude when the aircraft is operating in the ________ mode
unpressurised
45
The maximum differential pressure allowed in a pressurised aircraft is determined by the strength of the \_\_\_\_\_\_\_\_\_\_
aircraft structure
46
If the cabin rate of climb is too great, the rate control will cause the outflow valve to close \_\_\_\_\_\_\_ (Faster or Slower)
Faster
47
A negative-pressure relief valve is incorporated in a pressurisation system to prevent cabin pressure ever becoming _________ than the surrounding air pressure (lower or higher)
lower
48
Heat for the cabin of a jet transport airplane is provided by __________ air
compressor bleed
49
In a jet transport airplane, hot compressor bleed air is mixed with cold air from the ________ machine to get air of the correct temperature for the cabin
Air Cycle
50
Moisture that condenses from the pressurising air after it leaves the turbine is removed by the \_\_\_\_\_\_\_\_\_\_\_
water separator
51
Water is prevented from freezing in the water separator by routing some ________ around the air-cycle machine to mix with cold air and raise its temperature
warm air
52
In a vapor-cycle cooling system, heat from the cabin is absorbed into the refrigerant in the \_\_\_\_\_\_\_\_\_
evaporator
53
Heat taken from the cabin is transferred into the outside air by the \_\_\_\_\_\_\_
condenser
54
The refrigerant enters the evaporator as a _______ (high or low) pressure ______ (liquid or vapor)
**low** pressure **liquid**
55
The refrigerant leaves the evaporator as a ________ (high or low) pressure _______ (liquid or vapor)
**low** pressure **vapor**
56
The refrigerant enters the condenser as a _____ (high or low) pressure _______ (liquid or vapor)
**high** pressure **vapor**
57
The refrigerant leaves the condenser as a _______ (high or low) pressure ______ (vapor or liquid)
**high** pressure **liquid**
58
The receiver-dryer holds the refrigerant in its ______ (liquid or vapor) state
liquid
59
The two units that divide a vapor cycle system into a high side and a low side are the ______________ and the \_\_\_\_\_\_\_\_
thermostatic expansion valve compressor
60
The component in an air conditioning system that increases both the temperature and the pressure of the gaseous refrigerant is the \_\_\_\_\_\_\_
compressor
61
The condenser is in the ______ (high or low) side of an air conditioning system
high
62
The air conditioning system component that meters liquid refrigerant into the evaporator coils is the \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
thermostatic expansion valve
63
The evaporator is in the _______ (high or low) side of an air conditioning system
low

Mod 11: Systems (37 decks)

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