Aircraft Altitude and Refrigerant Quiz

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Questions and Answers

What is the basic system of cabin pressurization?

Arrange a constant inlet and vary the outlet (correct)

Arrange a constant outlet and vary the inlet

Arrange both the inlet and outlet

None of the above

What is the purpose of the differential capsule in a pressure controller?

To control cabin differential pressure (correct)

To maintain a constant cabin pressure

To control the rate of pressurization

To control cabin air flow

When is control of the rate of change of cabin pressure more important?

It is not important to control the rate of change

During ascent

Equally important during ascent and descent

During descent (correct)

What happens if the cabin pressure increases with the aircraft at maximum differential pressure?

All pressurizing air will be spilled overboard Signup and view all the answers

What happens if the cabin altitude increases above the normal maximum?

A warning light comes on in the cockpit Signup and view all the answers

Where is the water separator located?

Downstream of the turbine Signup and view all the answers

What is a comfortable rate of cabin altitude climb for passengers?

500 ft/min Signup and view all the answers

What should be checked before carrying out a ground pressure check?

Check all pitot and static lines are fitted Signup and view all the answers

What happens to the outflow valve on touch-down of the aircraft?

The outflow valve will be fully open Signup and view all the answers

What is the maximum velocity of air from the cabin ventilation system?

120 feet per second Signup and view all the answers

As an aircraft descends from cruising altitude, the cabin altitude will:

Decrease Signup and view all the answers

Which of the following systems utilizes a refrigerant?

Vapor cycle system Signup and view all the answers

If the signal line between the controller and discharge valve is leaking, the cabin pressure will:

Increase Signup and view all the answers

The primary function of a spill valve is to:

Control the flow of air into the cabin Signup and view all the answers

Which component is responsible for protecting the cabin altitude from reaching an altitude of 13,000 ft?

Altitude sensor Signup and view all the answers

If the cabin over-pressure relief valve opens, it indicates that:

The cabin pressure is too high Signup and view all the answers

What is the correct procedure for manually controlling the pressurization system?

Reset/disable the pressure controller Signup and view all the answers

What is the purpose of a sub-cooler in a typical vapor cycle system?

To superheat the vapor Signup and view all the answers

How is heat added to the air in an air conditioning system?

By restricting the compressor outlet Signup and view all the answers

Which component can be used on the ground to supply air in an air conditioning system?

Turbo fan Signup and view all the answers

What is the primary function of an air conditioning system?

To decrease the temperature of air Signup and view all the answers

What does an air cycle machine turbine do?

Drives the compressor to increase temperature Signup and view all the answers

What does the cabin differential pressure gauge in a pressurized aircraft measure?

The pressure difference between the inside of the aircraft and the ambient air pressure Signup and view all the answers

What happens when the pressure controller is set to 0 ft?

The cabin will not pressurize Signup and view all the answers

During a pressurization check at maximum differential pressure, if the engines are shut down, what happens?

The cabin rate of climb (ROC) indicator shows the cabin seal efficiency Signup and view all the answers

Where is the water trap located in a bootstrap compressor?

At the inlet of the turbine Signup and view all the answers

What happens to the cabin rate of climb (R.O.C.) during a normal pressurized climb after takeoff?

The cabin R.O.C. is less than the ambient R.O.C. Signup and view all the answers

When do the inward vent valves operate in a pressurized aircraft?

When the aircraft altitude exceeds the cabin altitude. Signup and view all the answers

What is cabin differential pressure?

The difference between cabin pressure and ambient pressure. Signup and view all the answers

What does cabin altitude represent in pressurized flight?

The altitude corresponding to the cabin pressure, regardless of the aircraft altitude. Signup and view all the answers

How is temperature conditioning mainly achieved in pressurized aircraft?

By extracting heat from the pressurizing air. Signup and view all the answers

If pressurization air comes from an engine compressor and there is an internal oil leak, what will happen?

The air will be contaminated. Signup and view all the answers

How does a cold air unit produce a drop in temperature?

By reducing pressure and driving the unit's compressor. Signup and view all the answers

What is the primary source of heating for pressure cabins?

Air supply heated by the pressurizing process. Signup and view all the answers

When an aircraft has reached maximum differential pressure and is at a constant altitude, what does the pressurization system allow?

A constant mass flow of pressurized air. Signup and view all the answers

What combination of components controls the ventilating and pressurizing air released to the atmosphere?

A pressure controller and discharge valve. Signup and view all the answers

Where is the silencer located in a 'blower' air conditioning system?

At the outlet of the blower Signup and view all the answers

When does a 'blower' air conditioning system produce the most air?

It is not affected by altitude Signup and view all the answers

What is the function of an air mass flow control valve?

Maintain a constant air mass flow into the cabin at all altitudes Signup and view all the answers

In a cabin air recirculation system, what proportions of fresh air and recirculated air are supplied?

60% fresh air, 40% recirculated air Signup and view all the answers

How is cabin pressure maintained in an air conditioning system?

By controlling the amount of air discharged from the cabin Signup and view all the answers

What controls the rate of change of cabin pressure during flight?

Most important in descent Signup and view all the answers

What is the purpose of an air-to-air heat exchanger in an aircraft?

To reduce the air supply temperature Signup and view all the answers

Study Notes

Cabin Pressurisation and Air Conditioning

During normal pressurized climb, cabin rate of climb (ROC) is less than ambient ROC.
Inward vent valves operate when cabin altitude exceeds aircraft altitude.
Cabin differential pressure is the difference between cabin pressure and ambient pressure.
Cabin altitude in pressurized flight is the altitude corresponding to cabin pressure, regardless of aircraft altitude.

Temperature Control

Temperature conditioning is mainly achieved by extracting heat from the pressurizing air.
Heating for pressurized cabins is obtained from air supply heated by the pressurizing process.
A cold air unit produces a drop in temperature by reducing pressure and driving the unit's compressor.
A cold air unit allows cabin temperatures to be a little more than ambient air temperature, despite compression heating.

Pressure Control

Control of rate of change of cabin pressure is more important in descent.
The purpose of the differential capsule in a pressure controller is to control cabin differential pressure.
The basic system of cabin pressurization is to arrange a constant inlet and vary the outlet.
Control of ventilating and pressurizing air released to the atmosphere is achieved by a pressure controller/dump valve combination.

Ventilation and Air Distribution

The velocity of air from the cabin ventilation system should not exceed 120 feet per second.
Air supplied for pressurization and conditioning is hottest from an engine compressor bleed.
An air-to-air heat exchanger is provided to reduce the air supply temperature.
Temperature control of cabin air is achieved by regulating the amount of air by-passing the cooling system.

Safety Features

A warning light comes on in the cockpit if the cabin altitude increases above the normal maximum.
On touch-down, the outflow valve will be fully open.
Ditching control is used to close the outflow valves.

System Components

A water separator is located downstream of the turbine.
A spill valve opens to control the flow to the cabin.
An air mass flow control valve is used to maintain a reasonably constant air mass flow into the cabin at all altitudes.

Testing and Maintenance

Before carrying out a ground pressure check, all pitot and static lines must be fitted.
On ground, internal doors, cupboards, etc. must be open during pressurization testing.
Prior to conducting a ground pressurization test, it is necessary to set QFE.

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Description

Test your knowledge on aircraft altitude changes and refrigerants with this quiz. Questions cover topics such as cabin altitude adjustments during descent and the use of refrigerants in different systems. This quiz is based on information from the Jeppesen A&P Technician Airframe Textbook.