Podcast
Questions and Answers
What is the primary function of the shut-off valve?
What is the primary function of the shut-off valve?
- To mix air and fuel in the engine
- To regulate the temperature in the aircraft
- To control the air flowing through to the flow control valve (correct)
- To regulate air pressure in the cabin
What triggers the shut-off valve to open?
What triggers the shut-off valve to open?
- A pneumatic signal from the engine
- An electrical signal from the air conditioning control panel (correct)
- A manual override from the pilot
- A mechanical signal from the air conditioning control panel
What is the function of the metering valve ball?
What is the function of the metering valve ball?
- To regulate the air pressure in the system
- To mix air and fuel in the engine
- To regulate the temperature in the aircraft
- To meter the air flow into the piston chamber (correct)
What is the purpose of the actuating piston?
What is the purpose of the actuating piston?
What is the function of the spring load on the piston?
What is the function of the spring load on the piston?
What does the flow control valve maintain?
What does the flow control valve maintain?
What is the purpose of the pressure ratio limiting unit?
What is the purpose of the pressure ratio limiting unit?
What is the source of the bleed air that enters the air cycle system?
What is the source of the bleed air that enters the air cycle system?
What are the three difficulties that have been solved with the advent of aircraft environmental systems?
What are the three difficulties that have been solved with the advent of aircraft environmental systems?
What is the primary function of air-conditioning in an aircraft?
What is the primary function of air-conditioning in an aircraft?
What is the result of a decrease in partial pressure of oxygen in the lungs?
What is the result of a decrease in partial pressure of oxygen in the lungs?
What is the approximate oxygen pressure at sea level?
What is the approximate oxygen pressure at sea level?
What is the term for the lack of sufficient oxygen reaching the cells in the body?
What is the term for the lack of sufficient oxygen reaching the cells in the body?
What is the purpose of pressurisation in an aircraft?
What is the purpose of pressurisation in an aircraft?
What percentage of the total air pressure is exerted by oxygen at any given altitude?
What percentage of the total air pressure is exerted by oxygen at any given altitude?
What is the consequence of hypoxia?
What is the consequence of hypoxia?
What is the primary function of the temperature selector in the cabin temperature control panel?
What is the primary function of the temperature selector in the cabin temperature control panel?
In automatic mode, what receives inputs from the temperature selector and temperature sensors?
In automatic mode, what receives inputs from the temperature selector and temperature sensors?
What happens when the mode selector is set to manual?
What happens when the mode selector is set to manual?
What is the main cause of dehydration at high altitude?
What is the main cause of dehydration at high altitude?
What type of switch is used in the manual mode?
What type of switch is used in the manual mode?
What is the ideal relative humidity for human comfort?
What is the ideal relative humidity for human comfort?
What is recommended when using manual temperature control?
What is recommended when using manual temperature control?
Why is it necessary to increase the moisture content of the conditioned air in an aircraft at high altitude?
Why is it necessary to increase the moisture content of the conditioned air in an aircraft at high altitude?
What type of aircraft typically has a simplified control panel?
What type of aircraft typically has a simplified control panel?
What is the purpose of the indicators in the cabin temperature control system?
What is the purpose of the indicators in the cabin temperature control system?
What is the purpose of a heat exchanger in a pressurisation system?
What is the purpose of a heat exchanger in a pressurisation system?
What type of information may be displayed on the indicators in some larger aircraft?
What type of information may be displayed on the indicators in some larger aircraft?
What is the ideal temperature range for human comfort?
What is the ideal temperature range for human comfort?
What is the effect of compression on air temperature?
What is the effect of compression on air temperature?
What is the primary factor that determines the source of air to pressurise an aircraft?
What is the primary factor that determines the source of air to pressurise an aircraft?
What happens when the mode selector is moved to 'manual'?
What happens when the mode selector is moved to 'manual'?
What is the primary function of the air distribution system?
What is the primary function of the air distribution system?
What happens to the air in the cabin after it is released from ceiling vents?
What happens to the air in the cabin after it is released from ceiling vents?
Where is the ducting typically located in the aircraft?
Where is the ducting typically located in the aircraft?
What is the purpose of the air distribution system in relation to lavatories and galleys?
What is the purpose of the air distribution system in relation to lavatories and galleys?
What is the result of the air flowing through the cabin and baggage compartments?
What is the result of the air flowing through the cabin and baggage compartments?
What should be done when using manual temperature control?
What should be done when using manual temperature control?
What is the characteristic of the air flow in the cabin?
What is the characteristic of the air flow in the cabin?
Study Notes
Shut-off Valve
- The shut-off valve controls air flow to the flow control valve and its design varies depending on the type and application.
- When bleed air is required, an electrical signal is sent to the solenoid, which moves the metering valve ball, allowing bleed air to flow.
Flow Control Valve
- The flow control valve maintains a pressure ratio between bleed air pressure and cabin air pressure.
- It solves problems caused by altitude, low temperature, and low humidity.
Effects of Altitude
- Hypoxia occurs when the lungs do not absorb sufficient oxygen due to decreased oxygen pressure.
- Oxygen pressure is approximately 1/5 of total air pressure, and at sea level, it is sufficient to saturate the blood.
- At high altitude, oxygen pressure decreases, leading to hypoxia.
Air Conditioning
- Air conditioning conditions air for human habitation and combats low oxygen pressure.
- Conditioned air is treated and circulated throughout the flight deck and cabin.
Humidity and Comfort
- At high altitude, air is dry, and humidity is low, leading to dehydration.
- The comfort zone for humans is 20°C to 30°C with 30% to 70% relative humidity.
Pressurisation Systems
- Sources of pressurised air vary with engine type.
- Air is cooled using heat exchangers or cold ambient air.
Cabin Temperature Control
- The control panel varies depending on the aircraft type.
- In automatic mode, the system processes inputs from temperature sensors and sends drive signals to mixing valves.
- In manual mode, the system is controlled by the temperature selector switch.
Air Distribution System
- The system distributes conditioned air to airplane zones, reduces engine bleed requirements, and removes offensive air from lavatories and galleys.
- Air is ducted from the pressurisation source into and throughout the cabin.
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Description
Learn about the design and operation of shut-off valves in aviation technical systems, including their role in controlling air flow to flow control valves.
