Air Conditioning Flashcards
where is the flight deck air sourced from
left pack outflow upstream of the mix manifold
what air is delivered to the mix manifold
- excess air from the left pack
- right pack
- air from recirculation system
what is a single pack operating in high flow capable of pressurizing the cabin to
41,000’
how many packs is the APU capable of supplying
- on ground = 2
- in flight = 1
how many packs can be supplied by 1 engine bleed system
1
when does the ram air inlet door fully open
- on ground
- slow flight with flaps out
when in cruise, in what position are the ram air inlets doors
modulate between open and close
what are the deflector doors’ purpose
installed forward of the ram air inlet doors to prevent slush ingestion during takeoff and landing
what controls the deflector doors
air-ground safety sensor
what controls the pack temperature control valves
electronic controllers command the pack temperature control valves to satisfy the demands
what happens if the primary pack control fails
affected pack is controlled by the standby pack in the opposite controller
what happens if the primary and standby pack controls fail for the same pack
the pack will continue to operate without control unless excessive temperatures cause the pack to trip off
what indications occur when a primary OR standby pack control fails
- PACK
- MC
- AIR COND system annunciator during recall
what indications occur when the primary AND standby pack controls fail for the same pack
- PACK
- MC
- AIR COND system annunciator
how many temperature control zones are there
3:
- flight deck (CONT CAB)
- FWD
- AFT
what are the selectable temperature ranges for each zone
18 - 30
how is the temperature modulated for each zone
- packs output lowest temperature demand
- each zone receives trim air to the respective zone supply ducts controlled by the trim air modulating valves
how is the temperature controlled in single pack operation (with trim air)
same as dual pack operation
how is the temperature controlled in single pack operation (no trim air)
pack output temperature will try command the average of all 3 zones
what happens if a zone supply duct overheat occurs
- “ZONE TEMP” light will illuminate
- associated trim air modulating valve will automatically shut
- reset is possible after the zone supply duct cools and the “TRIP RESET” button is pressed
what temperature zones do each electronic controller control
- left electronic controller controls:
- flight deck standby
- AFT cabin
- right electronic controller controls:
- flight deck primary
- FWD cabin
what happens following failure of the primary temperature flight deck control (system setup/indications)
- auto switches to backup
- CONT CAB “ZONE TEMP” light will illuminate upon MC recall
what happens following failure of the primary AND standby temperature flight deck control (system setup/indications)
- CONT CAB “ZONE TEMP” will illuminate immediately
what happens following the failure of the FWD OR AFT temperature control (system setup/indications)
- associated trim air modulating valves close automatically
- FWD and AFT temperature selectors are averaged
- “ZONE TEMP” when MC recall
what will cause the temperature control system to operate the PACKS independently
any failure affecting the supply of trim air
what happens if flight deck trim air is lost (pack output temperature)
- left pack will provide conditioned air to the flight deck at the selected temperature
- right pack will provide conditioned air to the cabin at the temperature requiring the most cooling
what happens if a cabin zone trim air OR all trim air is lost (pack output temperature)
- left pack will provide conditioned air to the flight deck at the selected temperature
- right pack will provide conditioned air to the cabin at the FWD and AFT averaged temperature
what happens if any individual zone is switched off
temperature selector will be ignored
what happens if all zone controls and primary pack controls fail (standby pack control)
- standby pack controls command the pack to produce air temperatures which will satisfy the average temperature demand of the 2 cabin zones
- trim air modulating valves will close
- flight deck zone temperature selector will have no effect on the standby pack controls
what happens if all temperature selectors are OFF (fixed temperature)
- left pack output temperature = 24
- right pack output temperature = 18
as measure at the pack temperature sensor
where does the cabin air distribute
cabin sidewall risers then to the overhead distribution duct then to the sidewall diffusers
-sidewall diffusers and overhead distribution duct send air to cabin
what are the recirculation fans’ purpose
reduce the pack and bleed loads by recirculating cabin air
where are the recirculation fans
forward cargo bay
how do the recirculation fans operate in AUTO
- IN FLIGHT:
- left fan operates if BOTH packs are operating (unless either PACK - HIGH)
- right fan operates if BOTH packs are operating (unless BOTH PACK - HIGH)
- ON GROUND:
- left fan operates unless BOTH PACK - HIGH
- right fan operates even if BOTH PACK - HIGH
what parts of the flight deck are part of the equipment cooling system
- electronic equipment
- E + E bay
what 2 ducts are part of the equipment cooling system
- supply duct
- exhaust duct
how many fans are there in each cooling equipment duct
2 (normal and alternate)
after selecting the equipment cooling ALTN fan how long will it take for the “OFF” light to extinguish
approximately 5s
what happens to the equipment cooling fans in the event of a FWD CARGO FIRE warning
(832 and beyond)
- equipment cool exhaust fan is turned off
- equipment cooling exhaust “OFF” light is inhibited
what happens if an equipment cooling overtemp occurs on the ground
call horn from in the nose wheel well
when the overboard exhaust valve is closed what happens to the equipment cooling system’s air
air from the equipment cooling is diffused into the FWD cargo compartments lining and recirculated back into the mix manifold for additional heating.
where does external air flow to
directly into the mix manifold
“ZONE TEMP” light
illuminated amber:
- CONT CAB: duct temp overheat OR failure of the primary flight deck and standby temperature control
- FWD CAB OR AFT CAB: duct temp overheat
during master caution recall:
- CONT CAB: failure of flight deck primary or standby temperature control
- either FWD CAB OR AFT CAB: failure of associated zone temperature control
- lights will extinguish when MC is reset
what does selecting the zone “temperature selector” to OFF do
closes the associated trim air modulating valve
“RAM DOOR FULL OPEN” light
indicates ram door in full open position
“AIR CONDITIONING PACK” sw
- OFF = pack signaled off
- AUTO:
- both packs operating - each pack = low flow
- 1 pack operating - operating pack = high flow in flight with flaps up
- 1 pack operating from APU (both ENG BLEED AIR sw - OFF) = high flow
- HIGH:
- pack regulates to high flow- provides max flow rate on ground with APU BLEED air switch ON
“TRIM AIR” sw
- ON = trim air pressure regulating and shutoff valve open
- OFF = trim air pressure regulating and shutoff valve close
“RECIRCULATION (RECIRC) FANS” sw
- OFF = fan signaled off
- AUTO:
- in flight:
- left recirculation fan operates if BOTH PACKS are operating unless EITHER PACK operating in HIGH
- right recirculation fan operates if BOTH PACKS are operating unless BOTH PACKS operating in HIGH
- on ground:
- left recirculation fan operates UNLESS BOTH PACKS operating in HIGH
- right recirculation valve operates even if BOTH PACKS operating in HIGH
- in flight:
“PACK” light
- indicates pack trip off or failure of both primary and standby pack controls
- during master caution recall = indicates failure of either primary or standby pack control (extinguishes when master caution is reset)
“TRIP RESET” switch
if condition is corrected, pushing will:
- reset “BLEED TRIP OFF, PACK, ZONE TEMP” lights
- related engine bleed air valve opens, or related pack valve opens or related trim air modulating valve opens
lights remain illuminated until reset
equipment cooling “OFF” lights
no airflow from the selected cooling supply/exhaust fan