Section 7- environmental control Flashcards
what is used to supply the cabin and cockpit with heated conditioned, or ambient air?
bleed air from both engines or ram air
where are the air outlets for environmental control?
- cabin floor
- cabin adjustable overhead
- cabin overhead trickle
- cockpit floor
- cockpit overhead
- demisting
what supplies the control functions of the heating/aircon system?
28v DC and 115v (400hz) AC
what protects the heating/aircon system?
- CABIN AIR/NON ESS BUS on AC/DC breaker panel
- CABIN AIR /115 AC BUS on the AC/DC breaker panel
what protects the bleed air valve of the LH engine?
- CABIN AIR/NON ESS BUS on AC/DC breaker panel
what protects the bleed air valve of the RH engine?
- RAM AIR/BLEED RH/ BUS 1 on the AC/DC breaker panel
where is bleed air tapped from?
the 2 engines
what does each bleed air line include?
- flow limiter
- shutoff valve which is solenoid controlled to provide an air on/off function
- a thermal duct to cool the bleed air
- a check valve designed to prevent cross feeding from one engine to the other
- downstream of the check valve the 2 bleed air ducts are united to a single line colocated with the tapping point of the optionally installed surface de-icing system
- the air is then fed through a combined pressure regulating and shutoff valve designed to regulate the pressure to the nominal value for supply to heating or air con
how does the heating and ventilation system work?
ambient air is drawn in by a fan and then distributed via ducting to the cabin and crew stations and the demisting system
how is heating provided?
hot air downstream of the bleed air pressure regulating and shutoff valve is added to the drawn in ambient air in a mixing chamber prior to its distribution to the compartments
what determines the amount of hot air added to the heating system?
the temperature regualtion system via the temperature control valve which is normally operated by the heat rheostat on the pneumatic control panel in the cockpit
what will a temperature rise above the preset temperature on the heating system trigger?
CABIN TEMP caution light
what must be selected to ensure correct cockpit and cabin ventilation if the heating system fails?
the ram air system
what occurs downstream of the pressure regulating and shutoff valve?
the precooked bleed air is divided into 2 routes which meet again at the mixing chamber
what will be displayed if the air pressure prior to entering the air conditioner is too high?
BLEED PRESS caution light
which 2 routes does the air take before meeting again at the mixing chamber?
- part of the air goes directly to the mixing chamber
- the other part of the air is routed to the mixing chamber via a heat exchanger and a cooling turbine
what regulates and shuts the mixing chamber?
temperature control valve controlled by the temperature controller
what are the 2 airflows mixed to establish in the mixing chamber?
cabin outlet temperatures between 18C and 28C
where does the air go from the mixing chamber?
routed through a water separator and 2 distribution lines to the air outlets in the cockpit and cabin
how is ambient air drawn in?
over the air-conditioning installation bay through the heat exchanger by a cold air unit fan
what is water from the water separator used for?
for better efficiency through extra cooling
what should be selected to ensure correct ventilation if the air con system fails?
ram air system
what operates the environmental control?
a pneumatic control panel on the co-pilots side
what positions can the 3 position AIRCOND selector switch be in for normal operation?
HIGH or NORM
