Air Conditioning Flashcards
How many temperature zones?
7 - The flight deck & 6 pax zones
The A/C System Supplies
Cabin & Cockpit
Forward, Aft, & bulk cargo Heat
Lav & Galley Ventilation
Gasper System
Shoulder & Foot Heater
Ventilation for lower crew rest & cockpit rest compartments
The left trim air system supplies:
the cockpit
3 zone ducts & the aft cargo compartment
The right trim air system supplies:
the other 3 zones ducts & the E & E bay.
An external conditioned air source can supply conditioned air directly
into the air conditioning manifold.
The flight deck receives 100 % fresh conditioned air, from the left pack and:
is at a slightly higher pressure to prevent smoke from entering.
External High Pressure Hot Air may be:
used during ground operations to feed hot air directly into the bleed manifold.
The Gasper system operates independently to the air conditioning system.
It supplies air from:
the aft distribution duct.
Operation of the ram inlet and exhaust doors is by a predetermined schedule set by the pack temperature controllers
in the AUTO mode.
The packs are capable of producing higher than normal air flow for air conditioning and pressurization under certain operating conditions. The high flow system is automatic
armed for operation at all times.
During ground operation whenever the APU or ground source is supplying air for air conditioning both packs increase airflow. In flight if one pack or recirculation fan is off, or inoperative,
pack airflow is increased.
Pack output is automatically limited during high bleed air demand periods such as
engine start or for gear retraction during take-off.
Zone target temperatures are shown in magenta, while actual temperatures
in white.
With the cabin temperature control in the auto position, and the trim air switches ON, the zone temperature controller provides automatic control for the system and uses feedback from various sensors to
determine the coldest zone requirement.
Remember the cabin management temperature control can only operate within +/- 10 ° of the master set temperature
and cannot exceed 65 ° to 85 ° temperature range.
selecting HIGH setting on the bulk cargo selector turns on the bulk ventilation fan,
which is provided for animal carriage.
The lavatory / galley vent fans draw air across temperature sensors in each compartment.
If both fans fail, cargo heat is not provided.
The EICAS advisory message CARGO HEAT AFT or BULK notifies the crew if a shutoff occurs or if a selector is off. Automatic overheat shutdowns prevent the related cargo heat
from being restored in flight.
With equipment in override, cooling for flight deck panels and the E & E compartment is by reverse air flow created by cabin differential pressure, which is adequate in cruise
but decreases as the airplane descends.
EQUIP. Cooling - Primary & Back up Fans
in AUTO
backup starts automatically if primary fails.
Lower Crew Rest Compartment (LCRC) - 1
×
AIRFLOW OFF light and an AIRFLOW / SMOKE RESET switch
The AIRFLOW OFF light indicates the valve supplying air to the LCRC is commanded closed due to one of the following:
airplane altitude is less than 25,000 ft; main compartment hatch is closed; during smoke detection mode; or the airplane is on the ground and the left pack is on.
The left ASCPC is considered the master and the right ASCPC the standby controller,
which will automatically take over, should the master fail.
Air supply and cabin pressure controllers (ASCPC)
send cabin pressure data to the
Airplane Information Management System (AIMS) and from the remote pressure sensor through the Electrical Load Management System (ELMS).
ASCPC in ground mode
commands the outflow valves fully open.
