Environmental Control System (ECS) Introduction Flashcards
What does the ECS consist of?
1) Aircraft cabin pressurization
2) Air-conditioning
3) Avionics cooling
4) Fuel tank pressurization
5) Anti-icing and defogging
6) Rain removal
What is the purpose of the pressurization system? What is in each cockpit to determine this?
- Primary purpose if to maintain the cabin pressure at an altitude below 10,000 ft.
- Cabin altimeter
What is the ACS?
- The ACS is the air conditioning system that operate in a wide range of thermal conditions, while also maintaining a suitable environment for the view, passengers and cargo.
What are two methods to cool engine bleed air?
1) Air-Cycle System
- Air passing through the system’s turbine is expanded and cooled.
- Cooled air is then remixed with hot air that has bypassed the turbine, to achieve the desired cabin
temperature
2) Vapour-Cycle System
- Have greater cooling capacity that air-cycle systems and are generally used for ground operations in hot ambient conditions.
What is rate of cabin change?
The rate of cabin change measured in feet per minute
What is cabin differential?
Difference between atmospheric pressure and he cabin pressure within a pressurized aircraft
What is fuel tank pressurisation?
Pressurization of the fuel tank
What are 2 advantages of fuel tank pressurization?
1) Maintains a constant positive pressure which reduces the tendency for fuel to vaporize at lower atmospheric pressures
2) Reduces the amount of induced water contamination, due to the use of engine-bleed supply conditioned air
3) reduces the rate of fuel expansion and contraction associated with non-pressurized systems.
How is cabin pressurization achieved?
The incorporation of an airtight fuselage and the supply of large quantities of conditioned air, sourced predominantly from the compressor stage of the engines.
What is the common compressor bleed air temperature and pressure?
200 C
30 psi
What does the pressure relief and shutoff valve do?
Terminates supply in the event of:
1) Over-pressurization
2) Inlet air contamination
3) Take-off performance demands in extreme conditions
What does the heat exchanger do?
Cools the hot bleed air
What does the cabin altitude controller do?
Maintains the cabin altitude and rate of change by varying the position of the outflow valves to regulate airflow.
What does the safety/dump valve do?
Ensure cabin differential pressure specifications are not exceeded due to abnormal operating conditions.
What do the pressure reducing valve/regulating valves do in the ACS?
Match the supply of air to the demand.
What do check valves do in the ACS?
Ensures the supply air travels in a single direction only
What are the crossfeed valves used for?
To facilitate the transfer of air from an alternate source to an area normally serviced by a supply source
What does the water separator do?
Removes moisture from the airstream through cyclonic separation
What does the Air Cycle Machine (ACM) do?
Supply conditioned dehumidified air for the various ECS operations
What are some advantages of the Air Cycle System?
- More effective utilization of ambient conditions
- Minimizes the weight and complexity of coolant-based refrigerant systems
- Reduction in associated system pressure enables lighter and less complex system construction
- Reduce maintenance
- Eliminates the toxicity and flammability issues associated with coolant-based systems
What are some disadvantages of the Air Cycle System?
- Comparatively less efficient than vapor cycle coolant-based systems
- Can require augmentation during on-ground operations during extreme heat conditions
What are the key components of a vapour cycle system?
1) Refrigerant
2) Refrigerant expansion (or Metering) Valve
3) Evaporator
4) Compressor
5) Discharge line
6) Condenser/Receiver
7) Oil Circulation
What are the two main sections of a VCS system?
- Low pressure which commences at the expansion valve
- High pressure which commences at the compressor
What is the most common supply for avionics cooling?
ECS air-cycle conditioning system which can be augmented by a range of alternate supplies such as ram air, liquid cooling or ground supply.
For Cockpit Temperature Control, where is temperature normally monitored ?
- The Cabin
2 The Cockpit - Conditioned air ducts
- Distribution air ducts
What is the purpose of an OBIGGS (OnBoard Inert Gas Generation System)?
To remove oxygen from compressed air to allow for fuel tank pressurization with just nitrogen.
What is used to cool aircraft cockpits and avionics on the ground?
- ECS airccyle
- Ram air
- Liquid cooling
- Ground supply
Temperature control is achieved by a Temperature Control Valve, how does it control the temp?
Through the temperature controller
What is another name for a vapour cycle system?
Closed system
