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
what happens if the 3 position AIRCOND selector switch is put to the RAM AIR position?
electrical power to the AIRCOND switch relay will be interrupted and the ram air shutoff valve will open
with airconditioing system installed the AC master switch will automatically return to the OFF position
where is the 2 position AIRCOND master switch usually held?
electromagnetically held in the ON position
when is the use of heating or airconditioing possible?
when BLEEDAIR is switched ON
when should both bleed switches be on?
in flight
when will the pressure regulating and shutoff valve be open?
when the AIRCOND master switch is ON electrical power will open it if one or both of the BLEEDAIR switches are in the ON position with the engines runnign
with the air-conditioning system installed when will the switch return to the OFF position?
whenever one or both of the ENGINE SPEED levers is above 85% and the gear is down and locked
what does the TEMP MODE switch allow?
selection of the automatic or manual cabin temperature control
what does the AUTO POSITION switch position do on TEMP MODE?
Temperature will be maintained automatically as selected by the heat control rheostat
what does the MAN switch position do on TEMP MODE?
temperature can be controlled via a 3 position MAN CONTR switch
when do we use MAN on TEMP MODE?
failed AUTO mode
what may happen with the airconditioing system if COLD has been selected with MAN CONTR or the temperature regulating system has failed in AUTO?
ice or snow may be created within the air ducts
what should we do if heating or cooling is required in MAN MODE?
MAN CONTR switch should be used in short bursts to either HOT or COLD until the desired temperature is reached to prevent an overheat condition or formation of ice
what will a continuous activation of the MAN CONTR switch for 10 seconds do?
fully open/close the temperature control valve
what does the temperature switch do?
monitors the temperature in the supply duct to the compartments
what if duct temperature exceeds 65C?
amber CABIN TEMP light will illuminate
how is distribution of air in the cockpit controlled?
CKP AIR slider
how is demisting controlled?
DEMISTING SLIDER
what is the RAM AIR system provided for?
to ventilate the cabin and cockpit if the heating or air con systems have been switched off
what does the ram air system use?
ram air normally shutoff by a shutoff valve, which is distributed to the cockpit and cabin through the heating/air con system distribution lines and outlets
what does the demisting system use?
air from the heating/airconditioing system or ram air depending on the pilots selection via the DEMISTING slider
is there a guaranteed minimum airflow to the windshield demister?
yes
where is the operating hours counter found if installed?
RH avionics rack
what does the operating hours counter record when aircon is switched on?
total air conditioning operating hours
what protects the cabin air system?
CAVBIN AIR/NON ESS BUS on the overhead breaker panel
where are the electrical cockpit heaters found if installed?
rear wall of the forward baggage compartment
where are the warm air outlets in the cockpit for the optional electrical heater?
in front of the rudder pedals
what are the optional cockpit heaters powered by?
2 position toggle switch labeled CKP HEAT
what are the optional cabin heaters powered by if installed?
2 position toggle switch labeled CABIN HEAT
what powers the optional cabin/cockpit heater?
28V DC
what protects the optional cockpit heaters?
CKP-HEAT LH
CKP-HEAT CONTR
CKP HEAT RH
all on NON ESS BUS on the AC/DC breaker panel
where are the optional electrical cabin heaters installed?
on the cabin floor in the rear cabin area near the side walls
what protects the optional cabin heaters?
CABIN-HEAT LH
CABIN-HEAT CONTROL
CABIN-HEAT RH
allow the NON ESS BUS on the LH avionics rack
when will the optional electric cabin/cockpit heaters switch off to protect from overheating?
when temperature in the duct exceeds 70C
